The one calculation that separates traders who survive from traders who don't: how much quantity to take so one wrong trade costs exactly what you planned — and nothing more. Works for NSE stocks and F&O lots.
Quantity sorted. Now the harder question — is this entry any good? VolumeLens shows you the order flow behind the price: footprint charts revealing who's aggressively buying or selling at your level, and an AI Mentor that narrates the chart out loud. Then it automates the risk side — trailing stops, breakeven locks and GTT OCO that work while you sleep.
Create Free Account →Position sizing answers one question: if this trade hits my stop, how much do I lose? Professional risk management fixes that number in advance — commonly 1-2% of capital per trade — and derives the quantity from it, instead of picking a quantity that feels right.
The formula this calculator runs:
Quantity = (Capital × Risk%) ÷ (Entry price − Stop price)
Example: ₹3,00,000 capital, 1% risk (₹3,000), entry ₹245.50, stop ₹238.00. Risk per share = ₹7.50, so quantity = 3,000 ÷ 7.50 = 400 shares (position value ₹98,200). If the stop is hit, the loss is ₹3,000 — exactly as planned, survivable a hundred times over. Without sizing, the same trader might "feel" their way into 1,500 shares and lose ₹11,250 on the identical trade.
For F&O, quantity comes in lots — the calculator rounds down to whole lots (rounding up would exceed your planned risk). If even one lot risks more than your limit, it shows zero: that's the tool telling you the stop is too wide or the contract too big for the account, which is information worth having before the trade.
It doesn't suggest where your stop should go, which stock to trade, or whether to trade at all — those are your decisions. It only does the arithmetic that keeps one decision from ending an account. VolumeLens is a screening and analysis tool, not a SEBI-registered investment adviser.
The most-cited convention is 1-2% of account capital per trade. At 1%, ten consecutive losing trades — a bad but survivable streak — costs about 10% of the account. The right number is personal; the calculator works with whatever you enter.
Same formula, then divided by the contract's lot size and rounded down to whole lots. NIFTY currently trades in lots of 65 — check the live lot size table since NSE revises lot sizes periodically.
Rounding up would risk more than the amount you chose. Position sizing exists to cap the loss; the round-down is the cap holding.
Yes — the math is identical. What changes is your stop distance and risk percentage choices, which are inputs, not assumptions.
No. The calculation runs entirely in your browser. Nothing you type is sent anywhere.
Every trade you size still needs a read on who's actually buying and selling. VolumeLens is India's first platform with footprint charts, DOM and volume profile for NSE — plus an AI Mentor that explains the chart in plain language, and automated trailing stops so the exit manages itself.