Margin Calculator
Estimate how much capital an F&O position actually needs — SPAN + exposure margin for futures and short options, or leverage-based margin for intraday equity — before you place the trade.
What margin actually covers
The exchange's worst-case estimate
NSE's SPAN system estimates the largest loss a position might reasonably suffer in one day, using a portfolio-based risk model recomputed from live data multiple times daily.
A buffer beyond SPAN
An additional margin layer to cover risks SPAN might not fully capture — sharp gaps, unusual volatility. NSE sets this at 3% of notional for index F&O, higher for individual stocks.
Premium only, no margin blocked
If you're buying (not writing) options, you only pay the premium upfront — your maximum loss is capped there, so no SPAN or exposure margin applies to that side of the trade.
- 01What is margin in F&O trading?
- 02SPAN margin vs exposure margin
- 03Why this calculator shows a range, not an exact figure
- 04A worked example, step by step
- 05Equity intraday (MIS) margin, explained separately
- 06What happens if your margin falls short
- 07Common margin mistakes to avoid
- 08How to use this calculator
What is margin in F&O trading?
Margin is the capital your broker requires you to set aside, as collateral, to open and hold a futures or options position — a fraction of the contract's full notional value, not the full amount. It exists because F&O positions are leveraged: a relatively small margin payment controls a much larger notional exposure, and the margin is the broker's (and the exchange's) protection against the position moving against you before you can close it or top up.
Margin is fundamentally different from the premium you pay when buying an option. An option buyer's maximum loss is the premium itself, paid upfront in full — there's no additional margin call possible. Margin only applies to futures positions and to selling (writing) options, both of which carry open-ended risk that needs to be collateralised.
SPAN margin vs exposure margin
Total F&O margin in India is made up of two distinct components:
SPAN margin
- The bulk of the total margin requirement
- Computed by NSE Clearing's portfolio-based risk model, using live volatility data
- Updated multiple times per trading day as market conditions change
- Cannot be reproduced exactly without access to NSE's live SPAN risk files
Exposure margin
- An additional buffer layered on top of SPAN
- Exactly 3% of notional value for index F&O — a fixed, published NSE rule
- The higher of 5% or 1.5× standard deviation for individual stock F&O
- This part is fully documented and exactly reproducible
Why this calculator shows a range, not an exact figure
This is worth being completely upfront about: true SPAN margin cannot be computed by any static formula or calculator, including this one. NSE Clearing's SPAN system is a live, portfolio-level risk computation that factors in current volatility, your entire portfolio of positions (not just one), and risk parameter files that update multiple times throughout the trading day.
This tool combines NSE's exact, published exposure-margin rule (3% of notional for index F&O) with an industry-standard approximate SPAN percentage range, based on typical observed margin levels for similar positions. The result is shown as a range, not a single misleadingly precise number, specifically so it doesn't look more accurate than it actually is. Always confirm the exact figure with your broker's own live margin calculator before placing a trade.
A worked example, step by step
Consider one lot of Nifty futures, lot size 65, with the index at ₹24,500.
| Step | Value |
|---|---|
| Notional value (24,500 × 65) | ₹15,92,500 |
| Approx. SPAN margin (8–12% of notional) | ₹1,27,400 – ₹1,91,100 |
| Exposure margin (3% of notional, exact) | ₹47,775 |
| Total estimated margin | ₹1,75,175 – ₹2,38,875 |
| Implied leverage | ~6.7x to 9.1x |
This range — roughly 11% to 15% of notional — is consistent with real-world index futures margin levels published by major Indian brokers, confirming the approximation is realistic even though it isn't an exact substitute for the live SPAN figure.
Equity intraday (MIS) margin, explained separately
Margin for intraday equity trades (commonly called MIS — Margin Intraday Square-off) works completely differently from F&O margin. It's simply your broker's quoted leverage multiplier applied to the notional value:
Margin Required = Notional Value ÷ Leverage Multiplier
A ₹1,00,000 intraday position at 5x broker leverage needs only ₹20,000 in margin — the remaining ₹80,000 is funded by the broker's intraday leverage facility, which must be repaid by squaring off the position before market close (or it gets auto-squared-off by the broker). MIS leverage varies by stock and by broker, and is subject to SEBI's peak margin rules, which have progressively reduced how much intraday leverage brokers can offer compared to a few years ago.
What happens if your margin falls short
If the market moves against your position and your account's available margin falls below the required maintenance level, your broker will issue a margin call — a demand to add funds or close part of the position. If you don't respond in time, brokers in India are required to square off under-margined positions, often automatically and without further warning, frequently at an unfavourable price during a fast-moving market. This is one of the most common ways traders take larger-than-expected losses on leveraged positions — not from being wrong about direction, but from being under-margined when a move went against them.
Common margin mistakes to avoid
- Treating margin as the maximum possible loss. Margin is collateral, not a loss cap — F&O losses can exceed the margin originally posted, especially on short options and futures during a sharp move.
- Assuming margin stays constant. SPAN margin changes with volatility, sometimes sharply, particularly around expiry, budget announcements, or major news events. A position that needed X margin yesterday may need significantly more today.
- Confusing option premium with margin. Buying an option only requires the premium; margin only applies to futures and short option positions. Conflating the two leads to badly underestimating capital needs for a short-options strategy.
- Ignoring the exact figure your broker shows before order placement. This calculator is for planning and ballpark sizing — always check the live, exact margin your broker's order screen shows before confirming a trade.
How to use this calculator
- Choose F&O or Equity intraday depending on the position you're planning.
- For F&O, select Index or Individual stock, and Futures or Short options.
- Enter the spot/contract price, lot size, and number of lots.
- Read the estimated SPAN range, exact exposure margin, and total margin range.
- Before placing any real trade, confirm the exact figure on your broker's own margin calculator or order screen.
Frequently asked questions
Because true SPAN margin is a live computation performed by NSE Clearing using risk parameter files that update multiple times a day, factoring in current volatility and your entire portfolio of positions. No static, client-side formula can reproduce that exactly — this calculator shows a realistic estimated range instead of a falsely precise number, and tells you to confirm the exact figure with your broker.
Yes. The 3% exposure margin for index futures and short index options is a fixed, published NSE rule, and this calculator applies it exactly. It's only the SPAN portion of the total margin that is shown as an approximate range, because that part genuinely requires live exchange data to compute precisely.
No. Buying (going long) an option only requires paying the premium upfront, in full, at the time of purchase. Your maximum possible loss is that premium, known in advance — no margin or margin calls apply to a long option position. Margin only applies to futures contracts and to selling (writing) options.
Because SPAN margin is volatility-sensitive. As implied or historical volatility in the underlying rises (often around events like results, expiry, or macro news), NSE's risk model increases the margin requirement to reflect the larger potential one-day loss. A quiet, range-bound market typically sees lower margin requirements than the same position during a volatile period.
SPAN margin applies to F&O positions (futures and short options) and is based on the exchange's risk model. MIS leverage applies to intraday equity (cash market) positions and is simply a broker-set multiplier on the notional value, subject to SEBI's peak margin caps. They are calculated completely differently and apply to different products.
Yes. Brokers are free to charge margin above the exchange-mandated minimum (SPAN + exposure) as an additional risk buffer of their own, particularly for volatile stocks or around major events. The figures from this calculator reflect estimated exchange-level requirements; your specific broker's actual requirement may be higher.