Plug in your account size, risk %, entry, and stop loss. Get the exact share or lot count that keeps every trade's rupee risk equal to your chosen percentage.
Track every trade's risk and R-multiple in your journal
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Start free trial →SEBI's 2024 disclosure showed 9 out of 10 F&O traders in India lose money. Across thousands of journals on ArthaLearn, the single strongest predictor of survival isn't the trader's entry signal or chart-pattern stack — it's whether they sized every trade consistently. A 60% win-rate trader who risks 5% per trade goes broke. A 40% win-rate trader who risks 1% per trade with average +1.5R wins compounds the account over time.
Position size (shares) = (Account size × Risk %) ÷ |Entry − Stop Loss|
Example: ₹5,00,000 account, 1% risk, entry ₹1,500, stop ₹1,470
= (5,00,000 × 0.01) ÷ |1500 − 1470|
= 5,000 ÷ 30
= 166 shares (round down to broker lot if F&O)Risk-of-ruin is the mathematical probability your account hits zero given your edge, win-rate, and risk-per-trade. At 1% risk per trade with a 50% win-rate and 1:1 reward, risk-of-ruin is < 1% over 1,000 trades. At 5% risk per trade with the same edge, risk-of-ruin climbs above 50% — i.e. you have a coin-flip chance of going broke before you double your account.