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Position Size Calculator

Work out how many lots or units to trade so a stop-loss loses only a fixed percentage of your capital.

Quick answer: The position size calculator converts a fixed-fractional risk rule into a concrete quantity. It takes your capital and the percentage you are willing to lose on the trade, works out the rupee risk budget, then divides that budget by the per-unit loss at your stop (stop distance in points multiplied by the point value of one lot). The result is the largest whole number of lots whose worst-case loss stays inside the budget.

Trading capital (₹)Risk per trade (%)

Entry priceStop pricePoint value per lot (₹)

How to use it

Enter your capital, the percent you will risk, and the entry and stop prices. Point value per lot is the rupee change in one lot for a one-point move in price (75 for a standard Nifty lot). The output shows the rupee risk budget, the loss per lot at your stop, the whole number of lots that fits, and the actual rupee at risk. It ignores brokerage, STT and slippage, which make the real loss slightly larger.

Formula

Lots = floor( (Capital × Risk% ÷ 100) ÷ ( |Entry − Stop| × Point value per lot ) )

Where the numerator is the rupee risk budget and the denominator is the loss on one lot if the stop is hit. floor() rounds down so the budget is never exceeded.

Frequently asked questions

Why does it round down to whole lots?

Exchange-traded futures and options in India trade in fixed lot sizes, so you cannot buy a fraction of a lot. Rounding down keeps the worst-case loss inside your risk budget rather than nudging it over.

What is point value per lot?

It is the rupee value of a one-point move in the instrument for a single lot. For a Nifty contract with a lot size of 75, one index point is worth 75 rupees per lot, so you enter 75.

It says zero lots. What does that mean?

Your risk budget is smaller than the loss on a single lot at that stop distance. Either widen the stop, increase the risk percentage, or accept that this trade does not fit your capital at that stop.

Does it include brokerage and taxes?

No. The figure is the raw price risk. Brokerage, STT, exchange fees and slippage add to the real loss, so treat the output as a floor, not the exact amount.

What risk percentage is sensible?

Many systematic traders cap single-trade risk at 0.5 to 2 percent of capital as a rule of thumb. This tool does not recommend a number; it simply sizes the position for whatever percentage you enter.

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