Short answer
What is position sizing in trading?
Position sizing in trading is deciding how many shares to buy so that, if the stop loss is hit, you lose only a fixed slice of your capital — usually 1%. The formula is quantity = rupee risk ÷ (entry − stop loss). The stop-loss gap, not the share price, decides the quantity, so every trade carries the same risk.
Key takeaways
- Quantity = risk per trade ÷ (entry price − stop-loss price), always rounded down to a whole share.
- Risk 1% of capital per trade by default and never more than 2%, however confident you feel.
- With ₹1,00,000 capital, a ₹130 entry and a ₹126 stop, 1% risk gives ₹1,000 ÷ ₹4 = 250 shares.
- If the formula gives less than one share, the trade is skipped rather than oversized.
- Ten straight losses at 1% leave about 90.4% of capital; at 10% they leave about 34.9%.
- The capital needed (quantity × entry) can exceed your account, so quantity is capped by available capital as well as by risk.
- Beginners keep a maximum of two to three open trades so total open risk stays small.
What is position sizing in trading?
Position sizing is the step between finding a trade and placing it: it decides how many shares you buy. Instead of buying a round number of shares or a round rupee amount, you fix how much you are willing to lose if the stop loss is hit and let that decide the quantity. The principle is simple — fix the risk and let the reward follow from the setup.
This matters because zone-based traders lose on a meaningful share of trades by design. A 1:2 risk-reward method can be profitable with fewer than half its trades winning, but only if every loss is the same controlled size. One oversized loss can erase the gains from several correctly sized winners.
How do you calculate position size in stock trading?
Multiply your capital by your risk percentage to get the rupee risk, subtract the stop loss from the entry to get the risk per share, and divide the first by the second. Round down to a whole share. The share price itself never enters the calculation; a ₹130 stock and a ₹1,300 stock with the same ₹4 stop gap get the same quantity.
Quantity = (Capital × Risk %) ÷ (Entry − Stop loss)For a short trade use (Stop loss − Entry). Always round down, never up.- Fix the rupee risk: capital × 1% (or up to 2% at most).
- Mark the entry just beyond the zone's proximal line and the stop just beyond the distal line.
- Compute the risk per share: entry − stop loss.
- Divide the rupee risk by the risk per share and round down.
- Check the capital required (quantity × entry) against what you actually have available.
How much should you risk per trade?
Risk 1% of total trading capital per trade as the default, and treat 2% as an absolute ceiling that confidence never overrides. The 1% rule keeps any single loss small enough to absorb calmly, and it lets you survive the losing streaks that every method goes through. For a swing trade held over days or weeks, the same 1% applies; overnight gaps are a reason to stay at 1%, not to stretch to 2%.
| Trading capital | 1% risk (default) | 2% risk (ceiling) |
|---|---|---|
| ₹50,000 | ₹500 | ₹1,000 |
| ₹1,00,000 | ₹1,000 | ₹2,000 |
| ₹2,50,000 | ₹2,500 | ₹5,000 |
| ₹5,00,000 | ₹5,000 | ₹10,000 |
| ₹10,00,000 | ₹10,000 | ₹20,000 |
What happens to your account after a losing streak?
When each loss is a percentage of the current balance, the capital left after N straight losses is (1 − r) raised to the power N, where r is the risk per trade. Small risk shrinks the account slowly; large risk compounds into damage that is hard to undo, because recovering a loss always needs a bigger percentage gain than the loss itself.
Remaining = (1 − r)^N Gain needed to recover = 1 ÷ Remaining − 1r = risk per trade as a decimal, N = number of consecutive losses.| Consecutive losses | 1% per trade | 2% per trade | 5% per trade | 10% per trade |
|---|---|---|---|---|
| 3 | 97.0% | 94.1% | 85.7% | 72.9% |
| 5 | 95.1% | 90.4% | 77.4% | 59.0% |
| 10 | 90.4% | 81.7% | 59.9% | 34.9% |
| 20 | 81.8% | 66.8% | 35.8% | 12.2% |
| Gain needed to recover after 10 losses | +10.6% | +22.4% | +67.0% | +186.8% |
What if the position size is less than one share?
If the formula gives a quantity below one, the trade is skipped. This happens with high-priced stocks or very wide zones, where the risk on a single share already exceeds your rupee risk. Buying one share anyway quietly breaks the 1% rule, and doing it whenever a setup looks good is exactly how position sizing stops protecting you.
What if the position needs more capital than you have?
A very tight stop can produce a quantity whose cost (quantity × entry) is larger than your whole account. Risk is then not the binding limit — capital is. Cap the quantity at what your per-trade capital allocation can buy, and accept that the actual rupee risk will be below 1%. Never borrow or use leverage just to reach the risk-based quantity.
Quantity = the smaller of [Risk ÷ (Entry − Stop loss)] and [Capital allocation ÷ Entry]How many trades should you keep open at once?
Beginners are better served by a maximum of two to three open trades at a time. More positions split attention, make each stop harder to honour and add up the open risk: three trades at 1% each means 3% of capital is exposed if all stop out together. Swing trades also lock capital for days or weeks, so keeping part of the account free lets you take the next valid zone without closing something early.
- Total open risk: add the rupee risk of every open trade; at 1% each, three trades put 3% at risk.
- Capital allocation: on ₹1,00,000, positions of roughly ₹30,000–₹40,000 each keep money available for new setups.
- Correlation: three trades in the same sector can behave like one large trade during a sector-wide move.
What are the most common position sizing mistakes?
Position sizing fails less often from bad arithmetic than from exceptions — the one trade where the rule felt too restrictive. These are the habits that most often turn a controlled loss into a large one.
- Sizing by share price or a round rupee amount instead of by the entry-to-stop gap.
- Rounding up the quantity, so the real risk ends up above the planned 1%.
- Raising risk after a win or to recover a loss, which concentrates risk at the worst moments.
- Buying one share when the formula says 0.4, quietly breaking the skip rule.
- Ignoring capital required, then using leverage to reach the risk-based quantity.
- Counting each trade alone and forgetting that several open trades add up to a much larger total risk.
- Moving the stop after sizing, which changes the rupee risk without changing the quantity.
Frequently asked questions
How much should I risk per swing trade?
A common framework is 1% of total trading capital per swing trade, with 2% as a hard ceiling. On ₹1,00,000 that is ₹1,000 per trade. Swing trades carry overnight and weekend gap risk, so staying near 1% gives room for a gap to push the loss slightly beyond the planned stop without real damage to the account.
Is the 1% rule based on total capital or the money in a single trade?
It is based on total trading capital, not the amount invested in the trade. Risking 1% of ₹1,00,000 means losing at most ₹1,000 if the stop is hit, even if the position itself costs ₹32,500. Confusing the two leads to either tiny positions or a stop that is far too wide.
Should I recalculate the 1% after every win or loss?
Recalculating on the current balance makes risk shrink after losses and grow after wins, which protects the account during streaks. Many traders update it weekly or monthly rather than after every trade for simplicity. Either way, never increase the percentage to win back a loss — only the capital base should change.
Does position sizing work the same way for intraday trades?
The formula is identical: rupee risk divided by the entry-to-stop gap. Intraday stops are usually tighter, so the quantity can become large, and the capital required may exceed your account. Apply the capital cap, account for costs that weigh more on small gaps, and keep the same 1% risk ceiling.
How StockNotify applies this
StockNotify's free position size calculator turns account size, risk per trade and stop distance into a whole-share quantity for NSE and BSE stocks. After sizing, StockNotify trade lifecycle alerts can watch the entry, stop loss and target you planned and notify you on Telegram or email, without connecting to a broker account.
Educational content only. Nothing here is investment advice or a recommendation to buy or sell any security. Chart diagrams use illustrative prices, not market data. Trading involves risk of loss; verify prices independently and apply your own risk process.