A position size calculator turns the share of your account you are willing to lose into a trade size. Position size in lots = (account balance × risk %) ÷ (stop-loss distance in pips × pip value per lot); with $10,000, 1% risk and a 25-pip stop on EUR/USD that is $100.00 ÷ $250.00 = 0.40 lots.
| Instrument | Account | Risk | Stop | Pip value / lot | Size |
|---|---|---|---|---|---|
| EUR/USD | $10,000.00 | 1% | 25 pips | $10.00 | 0.40 lots |
| USD/JPY | $10,000.00 | 1% | 30 pips | $6.67 | 0.50 lots |
| Gold (XAUUSD) | $5,000.00 | 2% | 50 pips | $10.00 | 0.20 lots |
| S&P 500 (US500) | $20,000.00 | 0.5% | 40 pips | $1.00 | 2.50 lots |
USD/JPY at 150.00; gold with a 0.10 “pip” and 100 oz per lot; the S&P 500 as a CFD of 1 unit per point per lot. Round the size down to what your broker allows.
Size follows from the stop, not the other way round. Put the stop where the trade idea is clearly wrong — beyond a level, or outside the market's normal swing — then size the position so that being stopped out costs your chosen percentage. A stop inside the normal 48-hour noise is likely to be hit by chance; PRISM's 80% range for each market is one way to see how wide that noise currently is.
Position size in lots = money at risk ÷ loss per lot at the stop, where money at risk = account balance × risk %, and loss per lot = stop-loss distance in pips × pip value per lot in US dollars.
With a $5,000 account, 2% risk and a 50-pip stop on gold (a 0.10 pip and 100 ounces per lot, so $10.00 per pip per lot): the money at risk is $100.00, the loss per lot at the stop is 50 × $10.00 = $500.00, and the position size is $100.00 ÷ $500.00 = 0.20 lots.
That is your decision. Many traders risk 0.5–2% of the account on one trade; the calculator flags anything above 2% as aggressive, because a short losing streak then takes a large bite.
No. The calculation runs in your browser, and nothing you type leaves it.