Position Size Calculator

Decide how many lots to trade from your capital, risk per trade and stop-loss — the single most important risk calculation in options trading.

Your parameters

Most professionals risk 0.5%–2% per trade.
Nifty 50: 75 · Bank Nifty: 35 · Sensex: 20 (check current contract specs — they change).

Result

Maximum position
0 lots
Risk budget ₹1,000.00
Risk per unit ₹50.00
Maximum units 0 units
Risk if stop is hit ₹0.00 (0% of capital)
Premium outlay at entry ₹0.00
Your risk budget is smaller than the risk of a single lot at these levels. Either widen your capital, reduce the stop distance, or take a cheaper strike — do not force the trade.

How position sizing protects your capital

Position sizing answers one question: if this trade goes wrong and my stop is hit, how much do I lose? Successful traders set that loss first and work backwards to quantity, instead of picking a lot count and hoping.

The formula

  1. Risk budget = capital × risk % per trade. On ₹1,00,000 at 1%, that is ₹1,000.
  2. Risk per unit = entry premium − stop premium. Entry ₹150, stop ₹100 → ₹50 per unit.
  3. Units = risk budget ÷ risk per unit = ₹1,000 ÷ ₹50 = 20 units.
  4. Lots = units ÷ lot size, rounded down. With lot size 75, 20 units rounds to 0 lots — the trade is too large for this budget.

Why whole lots matter

Index options trade in lots, so you cannot size to a fractional lot. That is why the calculator rounds down and shows the risk you actually take — sometimes the honest answer is that the trade does not fit your budget.

Related reading

Common questions

What risk percentage should I use?
Beginners should stay at 0.5%–1% per trade. Even a strong strategy hits losing streaks; small per-trade risk keeps a streak from ending your account.
Should the stop be on premium or the index?
This calculator uses premium differences because that is what determines your actual rupee loss on the option. If your stop is defined on the index, convert it to an approximate premium level first.
Why did it show zero lots?
One lot risks more than your budget allows. Use a closer stop, a cheaper strike, or accept that the setup is not sized for your account. Forcing oversized trades is the fastest way to blow up.
Does lot size change?
Yes. Exchanges revise contract lot sizes from time to time. Check the current specification on NSE or BSE before calculating.

Want these numbers to run themselves? HT Bot applies position sizing, targets and stop-losses automatically on Nifty 50, Bank Nifty and Sensex options — start with free paper trading.

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