IPO Lot Size: Calculation & Bidding Rules

What Exactly Is an IPO Lot Size?

When a company files for an IPO, it does not sell shares one at a time to retail applicants. Instead, it groups shares into standardised units called lots. A lot size is simply the number of shares in one such unit, and every retail or non-institutional investor must bid for at least one complete lot. You cannot bid for a fraction of a lot, and any bid that is not a whole-number multiple of the lot size is considered invalid and will be rejected during processing.

The practical implication is straightforward. Suppose a company sets its lot size at 60 shares and its price band at ₹200–₹210 per share. To place the minimum valid bid at the cut-off price of ₹210, you would need to block ₹12,600 in your bank account via the ASBA or UPI mandate process. If you want to apply for two lots, you block ₹25,200, and so on. The lot size thus acts as the fundamental unit of currency in the IPO subscription process.

The term is sometimes confused with the total issue size, which refers to how many shares the company is offering to the public in aggregate. These are completely different concepts. The issue size is measured in total number of shares or total rupee value being raised; the lot size is the per-investor minimum bidding unit. Another point of confusion arises with derivatives, where "lot size" refers to the contract size on NSE or BSE for futures and options. In the IPO context, the meaning is specific to primary market applications and allotment.

Each IPO prospectus - specifically the Red Herring Prospectus (RHP) filed with SEBI - clearly states the lot size along with the price band. This document is publicly available on SEBI's website, on NSE and BSE's corporate filings sections, and on the registrar's portal. Before you submit any application, verifying the lot size from the RHP rather than relying solely on third-party aggregator websites is good practice, since last-minute revisions sometimes occur before the issue opens.

Lot size also interacts with your investor category. SEBI defines three main categories for IPO applications: Retail Individual Investors (RII), Non-Institutional Investors (NII, also called HNI), and Qualified Institutional Buyers (QIB). Retail investors can apply for a maximum number of lots that keeps their total application value under ₹2 lakh. HNI and institutional investors operate under different ceilings. Understanding your category and the corresponding lot limits is just as important as knowing the lot size itself.

The Regulatory Framework: SEBI's Role in Setting Lot Size Rules

SEBI is the apex regulator of India's securities markets, and it exercises considerable authority over how IPOs are structured, priced, and allocated. The rules governing lot sizes flow primarily from SEBI's Issue of Capital and Disclosure Requirements (ICDR) Regulations, which are periodically updated. These regulations specify not just what the lot size must be but how it must be derived and what limits apply to different investor categories.

The cornerstone of the retail lot-size rule is the minimum application value principle. SEBI requires that the minimum application amount for a retail investor - that is, the cost of one lot at the lower end of the price band - falls within a defined monetary range. Historically, SEBI has set this range such that a single lot at the floor price amounts to approximately ₹10,000 to ₹15,000. The precise range has been revised over the years, and the ICDR regulations in force at the time of any particular IPO govern that offering. Always refer to the latest SEBI ICDR Regulations rather than a memorised figure.

This rule exists for an important reason. If lot sizes were set too small, small-value applications would flood the system, increasing administrative costs and making allotment logistics extremely complex. If they were set too large, retail participation would effectively be priced out for many ordinary investors. By anchoring the minimum application value in a defined rupee range, SEBI ensures that IPOs remain accessible to a broad cross-section of the investing public while maintaining manageable subscription infrastructure.

For SME IPOs - those listing on NSE Emerge or BSE SME - a different set of rules applies. SEBI permits SME issuers to set higher minimum application values, often in the range of ₹1 lakh or more per lot. This reflects the higher risk profile of SME companies, and SEBI's intent to limit SME IPO participation to investors who have a sufficient capital base and presumably a higher tolerance for liquidity and information risk. As a result, SME lot sizes can be anywhere from a few hundred to several thousand shares per lot, depending on the price per share.

SEBI also governs the maximum number of lots a retail investor can apply for. Because the maximum retail application value is capped at ₹2 lakh, the maximum number of lots a retail investor can bid for is simply ₹2,00,000 divided by the value of one lot (at the cut-off or upper price band), rounded down to the nearest whole lot. Any application above ₹2 lakh automatically shifts the applicant into the HNI (Non-Institutional Investor) category, with different allotment rules and a different proportion of the issue reserved for that bucket.

Beyond lot size minimums and maximums, SEBI also mandates how the three investor buckets - QIB, NII, and RII - receive shares in an oversubscribed issue. In a book-built IPO, at least 35% of shares are reserved for retail investors, at least 15% for non-institutional investors, and not more than 50% for QIBs, unless the issue qualifies for a different structure. Understanding these proportions in conjunction with lot size helps investors appreciate why their allotment probability changes as subscription levels rise.

How Lot Size Is Calculated: The Formula and the Maths

The calculation of an IPO lot size follows a straightforward mathematical approach, but the logic behind it deserves careful unpacking. The starting point is the price band set by the company and its merchant bankers. SEBI requires that the minimum retail application value - the cost of one lot at the lower end of the price band - should be approximately ₹10,000 to ₹15,000 (the exact mandated range is as per the SEBI ICDR Regulations applicable at the time of filing).

The basic formula is:

Lot Size = Target Minimum Application Value ÷ Floor Price (lower end of price band)

The result is then rounded up or down to a round, convenient number - often a multiple of 5, 10, 25, or some other denominator that makes the arithmetic neat.

For example, if a company sets its floor price at ₹140 per share and the target minimum application value is ₹14,000, the raw lot size calculation would be: ₹14,000 ÷ ₹140 = 100 shares per lot. Since 100 is already a round number, the lot size would be 100 shares.

If the floor price were ₹375 and the target minimum were ₹14,250, the calculation gives: ₹14,250 ÷ ₹375 = 38 shares. Since 38 is not a particularly round number, the merchant banker might round to 40 shares, which puts the minimum application at ₹15,000 - still within SEBI's permissible range.

The rounding and target amount selection involve some judgment by the company's lead managers, but they must stay within SEBI's mandated minimum application value range. If the floor price is very low - say ₹20 per share - you would need a lot size of 500 or more shares to achieve a minimum application value in the ₹10,000 range. Conversely, if the floor price is ₹1,500 per share, a lot size of just 7 or 8 shares would get the minimum application to roughly ₹10,500–₹12,000.

For SME IPOs, the same arithmetic applies but with a higher target minimum, as SEBI requires the minimum application value for SME issues to be significantly larger - often ₹1 lakh or more. This explains why you will routinely see SME IPO lot sizes of 1,000, 2,000, or even 3,000 shares: the issuer needs a large lot size to lift the minimum application value to the required level.

It is also worth noting that once the lot size is determined and disclosed in the RHP, it does not change even if the company prices the issue at the upper end of the price band. If the lot size is 75 shares and the issue is priced at the cap price of ₹210 (versus a floor of ₹200), your one-lot application at the cut-off price is still for 75 shares, but you block ₹15,750 instead of ₹15,000. This is one reason why bidding at the cut-off price - effectively agreeing to pay whatever the final issue price turns out to be - requires you to block funds at the upper price band when you submit the UPI mandate.

Investor Categories and Lot Limits: Retail, HNI, and QIB

One of the most practically important aspects of lot size is how it interacts with investor categories. SEBI divides IPO applicants into three main buckets, each with its own rules on how many lots can be applied for, how shares are allocated, and what the minimum and maximum application amounts are.

Retail Individual Investors (RII) are individuals applying for a total value of up to ₹2 lakh in a single IPO. This ₹2 lakh ceiling directly determines the maximum number of lots a retail investor can apply for. If the lot size is 75 shares and the cut-off (upper band) price is ₹210, one lot costs ₹15,750. The maximum number of lots a retail investor can apply for is therefore: ₹2,00,000 ÷ ₹15,750 = 12.69, which rounds down to 12 lots. If you try to apply for 13 lots, your total application value would be ₹2,04,750, which crosses the ₹2 lakh threshold and automatically re-categorises you as an HNI applicant.

The significance of this boundary matters because retail and HNI allotments are handled very differently. For retail investors in an oversubscribed IPO, the lottery-based allotment system means that every valid retail application has an equal chance of receiving one lot, regardless of how many lots the applicant bid for (once oversubscription is sufficiently high). For HNI applicants, allotment is proportional - larger applications receive proportionally larger allotments, subject to the bucket's available shares. Neither system is categorically better; they simply suit different strategies.

Non-Institutional Investors (NII), often called High Net Worth Individuals (HNI), are those who apply for more than ₹2 lakh. SEBI further divides this category into small HNI (applications between ₹2 lakh and ₹10 lakh) and large HNI (above ₹10 lakh) for allotment purposes under current regulations. The minimum number of lots for an HNI application is simply one lot more than the maximum allowed for retail - effectively, any application that pushes past the ₹2 lakh retail ceiling.

Qualified Institutional Buyers (QIB) include mutual funds, insurance companies, foreign portfolio investors, banks, and other entities recognised by SEBI. QIBs do not apply in lots in the same retail sense - they submit bids specifying both the number of shares and the price, and their applications are handled through the book-building process directly with the lead managers. The concept of lot size in the retail and HNI sense does not apply to QIBs in the same restrictive way.

For HNI applicants, the lot constraint still applies - you must bid in multiples of the lot size. But since the HNI bucket has no formal upper ceiling (other than the total issue size), you are free to bid for as many lots as you can finance. However, this comes with significant blocked capital requirements, since ASBA or UPI mandates freeze the full application amount until allotment and refund processes are complete.

Employee reservation portions, when companies offer them, may have separate lot-size or value norms. Similarly, shareholder quotas in certain IPOs might carry distinct eligibility and lot rules. Always read the specific RHP for the IPO in question to understand whether such special categories exist and what the applicable rules are.

Bidding Rules: How to Submit a Valid IPO Application

Knowing the lot size is only the first step. Applying correctly - in the right multiples, within the right value bracket, through the right mechanism - is what ultimately counts. A technically invalid application is rejected by the registrar without appeal, so precision matters.

The first rule: always bid in whole multiples of the lot size. If the lot size is 90 shares, valid bids are for 90, 180, 270, 360 shares, and so on. A bid for 100 or 150 or any number not divisible by 90 will be rejected.

The second rule: bid at or within the price band. In a book-built IPO, you must specify a price between the floor and the cap of the price band. Alternatively, you can select the cut-off price option, which means you agree to be allotted shares at whatever the final issue price turns out to be. Retail investors are always advised to bid at the cut-off price to avoid the risk of their bid price falling below the final issue price, which would result in their application being treated as invalid at the allotment stage.

The third rule: ensure sufficient funds are available for the full blocked amount. When you apply through the ASBA route (Application Supported by Blocked Amount), your bank blocks - not debits - the full application amount from the time of application until allotment or refund. If you apply for three lots at ₹15,750 per lot, your bank will block ₹47,250. If you do not have that amount in your account, the mandate will fail and your application will not be processed. Similarly, for UPI-based applications through your broker, the UPI mandate approval is triggered on your phone and must be approved within the timeframe specified by the exchange, failing which the application lapses.

The fourth rule: one PAN, one application per IPO. SEBI's rules prohibit multiple applications from the same PAN in the same IPO. If you accidentally submit two applications under the same PAN - even through different brokers or bank accounts - both may be rejected. If you are applying both as an individual and jointly (as first applicant), that would also constitute duplicate applications under the same PAN.

The fifth rule: submit before the closing time. IPO subscription windows are open for a defined period, typically three working days. On NSE and BSE, the cutoff time for retail applications on the last day is usually 5:00 PM IST, though brokers may set earlier internal deadlines to allow processing time. Applications submitted after the exchange's deadline will not be considered.

For HNI applications above ₹2 lakh (or above ₹5 lakh in some broker systems), the process is similar but typically handled via ASBA through a Self Certified Syndicate Bank (SCSB) rather than the UPI route, since UPI has a transaction limit. Always check the maximum UPI transaction limit applicable at the time of your application, as regulatory updates sometimes revise this ceiling.

Finally, bidding revisions are permitted during the subscription window. You can revise your bid price upward, increase or decrease the number of lots (subject to minimum and maximum limits), or withdraw your application entirely before the close. After the subscription window closes, no further changes are possible.

SME IPOs: A Different Lot-Size Universe

India's small and medium enterprise IPO market has grown substantially over the past decade, with hundreds of SME companies listing on NSE Emerge and BSE SME every year. While these platforms operate under a modified regulatory framework designed to facilitate fundraising by smaller companies, they are not without their complexities - and the lot-size rules for SME IPOs are starkly different from mainboard offerings.

SEBI mandates a significantly higher minimum application value for SME IPOs. Where a mainboard retail investor might need ₹10,000–₹15,000 for a single lot, an SME IPO applicant typically needs at least ₹1,00,000 (one lakh rupees) for the minimum application. The precise minimum has been revised over time, so always check the applicable SEBI circular and the specific RHP. The higher minimum is deliberate - it acts as a filter, ensuring that SME IPO investors have a meaningful capital base and are not casually dipping into a higher-risk segment.

As a consequence, SME lot sizes can be very large in share terms. If an SME company prices its shares at ₹50, it needs a lot of 2,000 shares to reach a ₹1 lakh minimum application value. If the price is ₹200, the lot size might be 500 shares. This means the capital commitment for even one lot in an SME IPO is substantially higher than in a comparable mainboard offering, even though the per-share price might be lower.

The investor category rules are also simplified for SME IPOs. The retail-versus-HNI distinction based on ₹2 lakh application value does not apply in the same way, because the minimum application itself often exceeds ₹1 lakh. Most applicants in SME IPOs fall into a single non-institutional category (since QIBs rarely participate in very small SME offerings), and allotment is on a proportionate basis rather than a lottery.

Another important distinction: SME IPOs are underwritten to a larger extent, and the due-diligence standards, while regulated by SEBI, are somewhat lighter than for mainboard companies. The information in the RHP may be less detailed, and the post-listing liquidity is typically lower. Bid-ask spreads on SME counters on NSE Emerge or BSE SME can be wide, and not every trading session has meaningful volume. This liquidity consideration is crucial for anyone thinking about the post-allotment experience.

For investors accustomed to mainboard lot sizes of 50–150 shares, the jump to SME lots of 1,000–3,000 shares can come as a shock, both psychologically and financially. The capital required per application can be ₹1 lakh to ₹3 lakh or more, and if the SME IPO is oversubscribed, the possibility of not receiving an allotment despite blocking a large sum is very real. Always factor in the opportunity cost of blocked capital when evaluating SME IPO participation.

Despite these differences, the procedural mechanics of applying are broadly similar: bid in multiples of the lot size, do not exceed the maximum application value (if any limit exists for your category), apply through ASBA or eligible UPI channels, and ensure your funds are available for blocking. The registrar and the BSE SME or NSE Emerge platforms handle the subscription, allotment, and listing process in a manner analogous to mainboard IPOs, though on slightly different timelines.

Allotment Mechanics: How Lot Size Affects Your Chances

Understanding lot size in isolation is only half the story. The real-world impact of lot size becomes vivid when you understand how allotment works in an oversubscribed IPO - which, for popular offerings, can mean subscriptions of 50, 100, or even several hundred times the shares available for a particular category.

For retail investors (RII category), the allotment methodology in an oversubscribed IPO follows a computer-generated lottery system administered by the registrar. Here is the key insight: in a heavily oversubscribed retail tranche, every successful retail application receives exactly one lot, regardless of how many lots that applicant bid for. If 1 crore retail applications are received but only 10 lakh lots are available, the lottery selects 10 lakh applications to receive one lot each. An applicant who bid for 12 lots has the same probability of winning the lottery as one who bid for 1 lot - because the unit of allotment is one lot.

This has a profound implication: when a retail IPO is very heavily oversubscribed, there is no benefit to applying for multiple lots from an allotment-probability perspective. The lottery selects applications, not lots. Your chance of receiving shares = (number of lots available) ÷ (total number of valid retail applications). Since each winning applicant gets one lot regardless of how much they bid for, bidding for the maximum number of lots does not improve your odds.

However, in a moderately oversubscribed IPO where there are enough lots to potentially give each applicant more than one, allotment is done proportionately until each applicant has at least one lot, and then lottery decides who gets additional lots. The exact methodology is governed by SEBI's standardised allotment procedure, which registrars follow uniformly.

For HNI applicants (NII category), allotment is proportional rather than lottery-based (under current SEBI norms, the small HNI and large HNI sub-categories each have a defined proportion of the NII bucket, with allotment done proportionately). A larger application receives a proportionately larger allotment. This incentivises HNI applicants to submit larger bids - but it also means they must block more capital.

The lot size thus becomes a pivotal number in calculating your allotment probability: the higher the subscription level in the retail tranche, the lower the percentage of applicants who receive an allotment of at least one lot. Subscription data - the number of times the retail tranche is covered - is updated live on NSE and BSE during the subscription period, giving investors a real-time signal of how competitive the allotment is likely to be.

In a scenario where the retail tranche is subscribed 80 times, roughly 1 in every 80 retail applications will receive an allotment (approximately). If you are in that unlucky 79-in-80 majority, your blocked funds are unblocked and returned to your account without any deduction, typically within a few days of the IPO closing. The timing of this unblocking follows SEBI's prescribed post-IPO timeline, which you can verify in the RHP.

This lottery dynamic also explains why some investors try to maximise their chances by applying through multiple family members' accounts (each with a different PAN) - a legitimate strategy, as each PAN is treated as a separate applicant. Each family member must apply independently using their own bank account and UPI handle, with funds available in that individual account. This is legal and widely practiced, though it requires careful coordination.

Price Band, Cut-Off Price, and Their Interaction with Lot Size

The price band and lot size are inseparable twins in the IPO universe. You cannot fully understand one without the other, and together they determine the precise rupee amount you must arrange for your application.

A price band is the range between which the company invites bids. SEBI rules require that the spread between the floor and cap of the price band cannot exceed 20% of the floor price for mainboard book-built IPOs. In practice, most companies set a narrower spread - often 5%–10% - to give investors clarity on the likely issue price. For example, a price band of ₹400–₹420 represents a 5% spread, while ₹400–₹480 would be the maximum permissible 20%.

The cut-off price option allows retail investors and eligible HNI investors to bid at whatever the final issue price turns out to be within the price band. When you select cut-off price, you authorise the registrar to allot shares at the final price determined through the book-building process, and your blocked amount is calculated at the upper end of the price band. If the final price is at the lower end, the difference is refunded or unblocked proportionately.

Now, consider how this interacts with lot size. Suppose the lot size is 85 shares, the floor price is ₹400, and the cap is ₹420. If you bid at the cut-off price for two lots: - Blocked amount = 85 shares × 2 lots × ₹420 = ₹71,400 - If the final issue price is ₹410, your actual payment = 85 × 2 × ₹410 = ₹69,700 - The difference of ₹1,700 is unblocked after allotment

If you bid at a specific price within the band - say ₹415 - and the final issue price is determined at ₹420, your bid is below the cut-off and your application becomes ineligible for allotment. You receive no shares, and your blocked amount is released. This is why retail investors are consistently advised to bid at the cut-off price.

The price band also affects the maximum number of lots a retail investor can apply for. As the upper end of the price band changes, the cost per lot changes, which shifts the maximum lot count. If the price band is ₹190–₹200 and the lot size is 75, one lot at cut-off costs ₹15,000, and the retail maximum of ₹2 lakh allows 13 lots (₹15,000 × 13 = ₹1,95,000, just within the limit). But if the same company had a price band of ₹195–₹210, one lot at ₹210 costs ₹15,750, and the retail maximum drops to 12 lots (₹15,750 × 12 = ₹1,89,000).

Fixed price IPOs - where the company sets a single price rather than a range - are simpler in this respect. The lot size interacts with just one price, so the minimum application amount is unambiguous. Retail investors apply at that fixed price; there is no cut-off option needed. However, fixed price IPOs are less common for mainboard listings; book building is the dominant mechanism.

It is also worth noting that for rights issues (where a listed company issues new shares to existing shareholders) and follow-on public offers (FPOs), lot-size concepts apply differently. Rights issues typically use a ratio-based entitlement rather than a fixed lot size, while FPOs broadly follow IPO lot-size conventions.

The UPI Mandate and ASBA Process in the Context of Lot Size

India's IPO application infrastructure has been modernised significantly over the past decade, and two mechanisms - ASBA and UPI-based applications - have become the standard. Both are deeply intertwined with lot size, because the amount blocked or mandated is a direct function of the number of lots applied for and the bid price.

ASBA, which stands for Application Supported by Blocked Amount, is the system through which your bank blocks the application amount in your savings account rather than transferring it to the company. The blocked amount stays in your account, earning any applicable interest, until allotment is finalised. Only if you receive an allotment is the proportionate amount actually debited; the rest is unblocked automatically. ASBA applications are submitted through Self Certified Syndicate Banks (SCSBs), which are banks authorised by SEBI to process IPO applications in this manner.

UPI (Unified Payments Interface) based applications have made the process even more accessible for retail investors. When you apply for an IPO through your stockbroker's app or a third-party platform, you enter your UPI ID, and the system sends a mandate request to your UPI-linked bank account. You receive a notification on your UPI app (such as BHIM, GPay, PhonePe, or your bank's native app) and must approve the mandate within the specified time window. Once approved, the bank blocks the application amount. The mandate amount is calculated as: lot size × number of lots × upper band price.

UPI-based IPO mandates have a per-transaction value limit set by NPCI (National Payments Corporation of India). The current limit has been increased progressively and, as of recent years, stands at ₹5 lakh for UPI IPO mandates - though this can be revised, so always confirm the current limit before applying. For applications above this limit (typical for HNI bids), you must use the ASBA route through an SCSB.

The connection to lot size is direct and arithmetical. If you apply for 10 lots of a retail IPO where each lot costs ₹14,400 (lot size 72 shares × ₹200 upper band price), the mandate amount is ₹1,44,000. Your UPI app will show a mandate request for exactly ₹1,44,000. If you do not have this amount available in your linked bank account, the mandate will fail and your application will not be processed. The registrar does not send reminder notices - a failed mandate simply means a lapsed application.

After the subscription window closes, the registrar finalises allotment. Allotment status is typically available within 6–7 working days on NSE, BSE, and the registrar's website. If you receive an allotment, the allotted amount is debited and the remainder (if any, due to a price below the upper band or partial lot allotment in specific scenarios) is unblocked. If you receive no allotment, the full blocked amount is unblocked. Shares are credited to your demat account within the SEBI-mandated timeline before listing on NSE or BSE.

Understanding the lot size before you initiate the UPI mandate process prevents common errors: insufficient balance, incorrect lot count entry, or miscalculation of the total mandate amount. Many investors assume the system will automatically validate or cap their application - it does not, in all cases. Entering an incorrect number of lots or applying at a price outside the band leads to rejection, and the application system's error messages are not always intuitive for first-time users.

Common Mistakes and How to Avoid Them

Despite the availability of detailed information in the RHP and on exchange websites, a surprisingly large number of retail IPO applications are rejected or lapsed every year due to avoidable errors. Most of these errors relate, directly or indirectly, to lot size and bidding mechanics.

The most common mistake is applying for a number of shares that is not a valid multiple of the lot size. This typically happens when investors enter share quantities manually rather than selecting lot counts from a dropdown. If the lot size is 67 and you type "200" in the quantity field, your application is invalid. Always verify that your application quantity equals an exact integer multiple of the lot size.

The second common mistake is exceeding the retail category limit. Investors who calculate the maximum lots incorrectly may accidentally apply for an amount above ₹2 lakh, moving themselves into the HNI category without realising it. This is not necessarily harmful - you may still receive an allotment - but the allotment methodology is different, and for very heavily oversubscribed IPOs, HNI allotments can be surprisingly small relative to capital blocked. Know your category limits before applying.

A third mistake is failing to approve the UPI mandate in time. The mandate request typically expires within a specific window - often a few hours or by a certain cutoff time - if not approved. Some investors apply and then forget to check their UPI app. The mandate lapses, the application is not processed, and the investor receives no allotment and no error notification. Set a reminder to approve the mandate as soon as you submit the application.

A fourth mistake is applying from an account that does not have sufficient cleared balance to cover the full application amount. Some investors have pending settlements or recently received funds that have not yet cleared. Ensure the full blocked amount - calculated as (number of lots × lot size × upper band price) - is available as cleared balance before submitting.

Fifth, applying multiple times under the same PAN is grounds for rejection of all applications. Even if you use different bank accounts or different brokers, the PAN is the unique identifier, and duplicate detection at the registrar level will flag and reject all applications linked to that PAN for that IPO. If you want to maximise applications per IPO, use different eligible family members' PANs, each applying through their own accounts with their own funds.

Sixth, confusion about SME versus mainboard lot sizes catches some investors off guard. If you have been primarily tracking mainboard IPOs and then look at an SME offering, the lot size can appear shockingly large. Before committing to an SME IPO application, calculate the total application amount (lot size × upper band price × number of lots) and confirm you are comfortable with the capital commitment and the associated risks, including lower liquidity post-listing.

Finally, not reading the RHP is itself a mistake. The RHP contains the definitive lot size, price band, application schedule, allotment methodology, and risk factors. Third-party websites aggregate this information but may lag updates or contain errors. The RHP, available on SEBI's primary market disclosure portal and on NSE and BSE filings, is the authoritative source.

Lot Size Changes and Adjustments: What Can Change and When

One aspect of lot size that surprises many investors is that it can, in limited circumstances, change even after the RHP has been filed. Understanding when and why this happens helps you stay alert and avoid applying based on outdated information.

The most common scenario in which lot size information changes is a price band revision. SEBI permits companies to revise their price band during the subscription period under certain conditions. If the price band is revised upward, the minimum application value for one lot increases. If it rises above SEBI's prescribed ceiling for retail minimum application values, the company may need to correspondingly reduce the lot size to keep the minimum within the permitted range. Conversely, a downward revision of the price band - while rare - can prompt an increase in lot size. Any such revision must be announced publicly and reflected in an updated RHP or addendum.

Another scenario is withdrawal and re-filing. If a company withdraws its IPO and subsequently re-files with SEBI (perhaps after a market correction or a change in business fundamentals), the new RHP may carry a different price band and, consequently, a different lot size. Investors tracking the IPO based on the original documents would have outdated information.

Post-listing adjustments to lot size do not apply to the IPO process itself, but they are relevant in the secondary market context. After a company lists on NSE or BSE, its shares trade in the standard market lot of 1 share (all listed shares trade in single units in the cash segment). The IPO lot size is relevant only for the application process. Once listed, you can buy or sell any number of shares through the exchange.

In the derivatives market, however, futures and options contracts carry their own lot sizes, which are determined by SEBI and the exchanges based on the stock's market capitalisation and price. These derivative lot sizes are unrelated to the IPO lot size and are subject to periodic revision by the exchanges. When reading financial news, pay attention to the context - "lot size" in a derivatives story means something different from "lot size" in an IPO story.

For rights issues and bonus issues - which occur post-listing - the concept of lot size re-emerges in a modified form. Rights issues are offered in a ratio relative to holdings (e.g., 1 new share for every 4 held), and the minimum application is typically one rights entitlement. Bonus issues do not require applications. Neither should be confused with the IPO lot-size framework.

Finally, when SEBI updates its ICDR regulations, the minimum application value parameters can change, and this will flow through to how future IPO lot sizes are calculated. For instance, if SEBI were to revise the target minimum retail application value from the current range to a higher figure to account for inflation, all subsequent IPOs would have their lot sizes recalculated using the new target. Staying current with SEBI circulars, which are publicly available on SEBI's official website, is the best way to keep your knowledge up to date.

Example

Key benefits

How it works

1. 1
   Company Files the RHP

   The company submits its Red Herring Prospectus to SEBI, disclosing the proposed price band. The lot size is calculated based on SEBI's minimum application value guidelines and the floor price, and is disclosed in the RHP.

2. 2
   Investor Checks Lot Size and Price Band

   Before the subscription window opens, the investor reads the RHP or verified exchange filings on NSE or BSE to confirm the lot size, price band, and application schedule.

3. 3
   Investor Selects Number of Lots

   The investor decides how many lots to apply for (minimum 1, maximum determined by the ₹2 lakh ceiling for retail), ensuring the total application value stays within their category's permissible range.

4. 4
   Application Submitted via ASBA or UPI

   The investor submits the application through their broker's platform or SCSB, selecting the cut-off price option and specifying the number of lots. The system calculates the total mandate amount (lots × lot size × upper band price).

5. 5
   Funds Are Blocked

   For UPI applications, the investor approves the mandate on their UPI app within the specified window. For ASBA, the SCSB blocks the amount in the savings account. The funds remain in the account but cannot be used until unblocked.

6. 6
   Allotment Determination

   After the subscription window closes, the registrar processes all applications. For oversubscribed retail tranches, a computer-generated lottery selects which applications receive one lot each. Allotment status is published on NSE, BSE, and the registrar's portal.

7. 7
   Settlement and Listing

   Successful allottees have the allotted amount debited and shares credited to their demat account within SEBI's prescribed timeline. Unsuccessful applicants have their full blocked amount released. The stock then lists and begins trading on NSE or BSE.

Formula

Lot Size = Target Minimum Application Value (as per SEBI ICDR Regulations) ÷ Floor Price of the IPO (rounded to a convenient whole number)
Maximum Lots for Retail = Floor of (₹2,00,000 ÷ (Lot Size × Upper Band Price))

Key takeaways

Frequently asked questions

Related terms