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Calculator

Position Size Calculator

Decide the stop first, then the size. Enter your capital, the share of it you are willing to lose on one trade, and your entry and stop prices to get the right quantity or number of lots.

Most professionals risk 0.25% to 2% of capital on a single trade.
NSE lot sizes change from time to time (for example NIFTY 65 and BANKNIFTY 30 in 2026). Check the current lot size on NSE before trading.
Maximum loss allowed
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Position size
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Actual risk if stopped out
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Reward : risk
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What a losing streak would do at this risk level

Losses in a rowCapital leftDrawdownGain needed to recover

Capital after consecutive losses, by risk per trade

How position sizing works

Position sizing answers one question: how many shares or lots can you buy so that, if your stop loss is hit, you lose no more than a fixed share of your capital? The size comes from the stop, not from how confident you feel or how much margin your broker allows.

Risk budget = Capital × Risk per trade %
Risk per unit = |Entry price − Stop-loss price|
Quantity = Risk budget ÷ Risk per unit  (rounded down to whole lots)

Example: with ₹5,00,000 of capital and 1% risk per trade, the most you should lose on one trade is ₹5,000. You plan to buy an option at 120 with a stop at 90: 30 points of risk per unit, or ₹1,950 per lot of 65. That allows 2.56 lots, so you trade 2, and the real risk is ₹3,900.

Why a small percentage matters

Losing streaks are normal even for good strategies. At 1% risk per trade, ten losses in a row cost about 9.6% of the account. At 5% they cost 40.1%, and recovering from that needs a gain of 67%. The table beside the calculator shows this for your own risk level. Our risk of ruin article simulates 10,000 traders to show how risk per trade changes the odds of a deep drawdown.

Limits of stop-based sizing

  • Gaps and slippage. A stock or index can open far beyond your stop after news, and options can jump. Your real loss can exceed the planned risk. Size a little smaller for overnight positions.
  • Sold options. For an option you sell, the loss is not limited to the premium. Size by a stop on the option price or a stress move in the underlying, never by the margin blocked.
  • Correlated positions. Three trades in the same direction on NIFTY, BANKNIFTY and a bank stock are close to one big trade. Cap your total open risk, for example at 5% of capital.
  • Costs. Brokerage, STT (0.15% on the premium for options sold and 0.05% on futures from 1 April 2026), exchange fees and GST add to each loss.

Frequently asked questions

What risk per trade should I use?

Beginners are usually advised to risk 0.5% to 1% of capital per trade. Even experienced traders rarely exceed 2%. Lower risk means smaller swings in your account and more time to learn from mistakes.

What if the calculator says zero lots?

It means one lot would risk more than your budget at that stop distance. Skip the trade, wait for an entry closer to a logical stop, or trade a smaller instrument. Do not widen your risk budget to fit the trade.

Should I use the margin required to size my trade?

No. Margin is the deposit the exchange requires; it says nothing about how much you can lose. Size every trade from the distance to your stop loss.

Does this work for short trades?

Yes. If your stop is above the entry price, the calculator treats the trade as a short and measures risk the same way.

This calculator is for education and planning. Results depend entirely on the assumptions you enter and are not a forecast, a guarantee or investment advice. Everything runs in your browser; nothing you enter is sent to us. Read our disclaimer. Built and checked by Pradeep Rawal.