Lot Size

Quick Answer

Lot size is the fixed quantity of the underlying in one derivatives contract, so every Nifty option or future trades in whole multiples of it. It scales cost and risk: at the Nifty lot of 65 (cut from 75, effective 28 October 2025), a ₹100 premium means ₹6,500 per lot. The NSE revises lot sizes periodically.

Lot Size — key takeaways

Lot Size at a glance

Lot Size in simple words

Lot size is how many units of the underlying make up one derivatives contract. You cannot trade a single unit of Nifty as a derivative — you trade it in a bundle called a lot. As of the January 2026 expiries the Nifty lot size is 65 (revised down from 75), so one option or futures contract controls 65 units of the index, and everything — premium, profit, loss and margin — is multiplied by 65. The exchange fixes lot sizes so that one contract has a sensible minimum value, and it revises them periodically as index levels change.

Lot Size — detailed explanation

What lot size means and why it exists

Lot size is the exchange-defined bundle in which a derivative trades. Rather than let contracts be any size, the NSE standardises each underlying to a fixed number of units per contract so that every Nifty future or option represents the same quantity. Standardisation makes contracts fungible and liquid, and it sets a minimum contract value that keeps derivatives meaningful for institutions while limiting how small a position can be. You always trade in whole lots — one, two, three — never a fraction of a lot.

How lot size scales premium, profit and loss

Lot size is the multiplier on every rupee figure in a trade. If a Nifty call has a premium of ₹120 and the lot size is 65, the cost of one contract is 120 × 65 = ₹7,800. A 40-point gain in that option is worth 40 × 65 = ₹2,600 per lot. This is why a small-looking per-share premium becomes a substantial rupee amount: the lot size turns points into money. Reading a price without multiplying by the lot is the most common way beginners misjudge their true exposure.

How exchanges set and revise lot sizes

The NSE sets each underlying's lot size and revises it periodically, guided by SEBI's framework that a derivatives contract should have a minimum value (raised to ₹15 lakh in a 2024 SEBI review, up from the earlier ₹5–10 lakh band). As an index rises, a fixed lot represents a larger rupee value, so the exchange may cut the lot size to keep contract value in range; when a market falls, lots can be increased. The most recent such revision came via NSE circular NSE/FAOP/70616 (dated 3 October 2025, effective 28 October 2025 EOD, with the new lots applying from the January 2026 expiries): the Nifty 50 lot was cut from 75 to 65, Bank Nifty from 35 to 30, FinNifty from 65 to 60 and Nifty Midcap Select from 140 to 120, while Nifty Next 50 stayed at 25. Because these numbers change, any specific lot figure must be read as of a date and verified against the current NSE contract specification.

Lot size, margin and position sizing

Lot size is the atom of position sizing because it fixes the smallest step you can take. Your risk per trade is the rupee move times the lot size times the number of lots, so you size a position by choosing how many lots keep the worst-case loss within your limit. Lot size also drives margin: a larger lot means a larger contract value and therefore a larger SPAN-plus-exposure margin to sell options or hold futures. The margin and position-sizing mechanics are covered on RiskManagementGyan.

Formula

Lot Size — practical example (Nifty)

Why Lot Size matters in practice

• Lot size is the fixed number of underlying units in one derivatives contract, set by the exchange.
• Every rupee figure — premium, profit, loss, margin — is multiplied by the lot size.
• You can only trade whole lots; the lot is the smallest position-sizing step available.
• Lot sizes are revised periodically by the NSE as index levels and SEBI's minimum-contract-value rules change.

Common misconceptions about Lot Size

• Misconception: A smaller lot size automatically means a smaller-risk trade.
  Reality: Risk depends on the premium or move multiplied by the lot size and the number of lots, not on the lot number alone. A small lot on an expensive or fast-moving option can risk more than a larger lot on a cheap one — the lot is only one factor in the rupee exposure.

Common mistakes with Lot Size

• Reading a per-share premium and forgetting to multiply by the lot size, badly underestimating the money at risk.
• Assuming a smaller lot size means a smaller-risk trade, when risk depends on premium and lots, not the lot number alone.
• Using an outdated lot size after the NSE has revised it, so position sizing and margin estimates are wrong.
• Sizing by how many lots the account can afford rather than by the rupee loss a worst-case move would cause.

How professionals use Lot Size

Experienced traders treat the lot size as the unit of risk, not just a contract detail. They translate every idea into rupees per lot before trading — premium per lot, worst-case loss per lot, margin per lot — and then decide how many lots keep the trade within their risk-per-trade limit. They re-check lot sizes after any NSE revision, because a changed lot silently alters exposure and margin on every position in that underlying.

Lot Size — frequently asked questions

Sources & references

• NSE India — F&O list of underlyings & market lots
• SEBI — Securities and Exchange Board of India (derivatives framework)
• NSE India — Equity Derivatives (introduction)