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How much to risk on a single trade — the single biggest survival skill.
Reading candlesticks, spotting support and resistance, and watching moving averages all help decide where to enter a trade. But none of them answer a question that matters just as much — how much money should actually go into that trade? Position sizing is what separates a single bad trade from a single trade that ends a trading account.
Position sizing is the process of deciding how many shares or how much capital to commit to a single trade, based on how much you're willing to lose if it goes wrong — not on how confident you feel about it. It's calculated from three things: total trading capital, the percentage of that capital you're willing to risk on one trade, and the distance between your entry price and your stop-loss.
Illustration
A trader has ₹1,00,000 in capital and decides to risk only 1% of it — ₹1,000 — on any single trade. They plan to buy a stock at ₹500 with a stop-loss at ₹480, a ₹20 risk per share. Dividing the ₹1,000 risk budget by the ₹20 per-share risk gives a position size of 50 shares — not because that "feels right," but because it's the exact quantity that caps the loss at ₹1,000 if the stop-loss is hit.
A widely used starting point among traders is risking no more than 1% of total capital on any single trade. It sounds conservative, but the math behind it is what makes position sizing so important — losses compound against you faster than gains recover them.
| Loss on Capital | Gain Needed Just to Recover |
|---|---|
| 10% | 11.1% |
| 25% | 33.3% |
| 50% | 100% |
The table above is the entire reason position sizing exists. A 10% loss only needs an 11.1% gain to recover — annoying, but manageable. A 50% loss needs a 100% gain just to get back to even, which can take far longer and often never happens at all. Small, controlled losses from disciplined position sizing stay recoverable. Large losses from oversized positions can wipe out months of gains in a single bad trade.
A scalper or intraday trader using leverage is exposed to much sharper moves in a short time, so position sizing usually needs to be tighter to account for that amplified risk. A swing trader, holding through overnight gap risk, needs to size positions so that even an unexpected gap against them stays within their risk budget. There's no single "correct" position size across every style — it always comes back to the same formula: risk budget divided by risk per share.
1. Sizing a position based on conviction, not risk
Putting in extra capital because a trade "feels certain" ignores the fact that even high-conviction trades fail — oversizing on confidence is how a single trade can do outsized damage.
2. Widening the stop-loss to justify a bigger position
Working backward from "I want this many shares" and stretching the stop-loss to fit, instead of letting the stop-loss and risk budget determine the position size in the first place.
3. Increasing size after a string of losses to "win it back faster"
Trading larger to recover a losing streak faster does the opposite — it increases the risk budget exactly when discipline matters most, often turning a recoverable drawdown into a much deeper one.
Key Takeaway
Position sizing decides how much capital goes into a trade based on a fixed risk budget and the distance to the stop-loss — not on confidence or gut feel. Because losses need disproportionately larger gains to recover from, keeping any single trade's risk small (commonly around 1% of capital) is what keeps one bad trade from becoming a account-ending one, regardless of trading style.
No, it's a common starting guideline, not a fixed rule. Some experienced traders risk slightly more or less depending on their strategy and risk tolerance, but the underlying principle — keeping any single trade's risk small — stays the same.
Divide your risk budget for the trade (capital × risk %) by the per-share risk (entry price minus stop-loss price) — the result is the number of shares to buy.
Yes — leverage amplifies both gains and losses, so the same risk-budget calculation needs to account for the larger effective exposure leverage creates, not just the margin actually put down.
A tighter stop-loss allows a larger position size for the same risk budget, since the per-share risk is smaller — but it also means the trade is more likely to get stopped out by normal price noise.
Not necessarily the same number of shares, but the same risk percentage per trade — since stop-loss distances vary from trade to trade, the actual quantity will naturally differ even when the risk budget stays constant.
It matters most in trading, where stop-losses and shorter timeframes make risk very concrete — long-term investors think about a related idea, diversification and allocation, but usually don't calculate position size trade-by-trade the same way.