Tools · Position Size Calculator
Position Size Calculator
Decide how much you are willing to lose first, then let the stop-loss set the lot size. Enter your balance, risk and stop distance. It runs in your browser and sends nothing anywhere.
Calculate lot size
The formula
How do you calculate position size in forex?
Position size is how many lots you can trade so that a stop-loss hit costs only the amount you chose to risk. Lots = (account balance × risk %) ÷ (stop-loss in pips × pip value per lot). Fix the risk first, then let the stop distance set the size.
Formula. Money at risk = balance × risk %. Pip value per lot = contract size × pip size × conversion rate to your account currency. Lots = money at risk ÷ (stop-loss in pips × pip value per lot), rounded down to 0.01.
The result is rounded down so the stop never risks more than your target. Platforms set their own minimum lot and lot step, so confirm those for your account. The calculator shows the money actually at risk at the rounded size.
How to use it
How do you use the position size calculator?
Enter your balance and account currency, the percentage you will risk, and the stop-loss distance in pips. Pick the instrument so pip size and contract size are filled in. If the quote currency is not your account currency, add the conversion rate yourself.
- ✓ Enter your balance and the percentage of it you accept losing if the stop is hit.
- ✓ Measure the stop in pips from your entry, based on the chart and not on the size you want.
- ✓ Choose the instrument, or select “Custom” and enter the pip size and contract size.
- ✓ Read the lots and the money at risk, then check them against the figures in your platform.
Worked example
What lot size risks 1% with a 50-pip stop?
Hypothetical example: a balance of 10,000 USD risking 1% puts 100 USD at risk. On EUR/USD one pip is worth 10 USD per lot, so a 50-pip stop costs 500 USD per lot. Lots = 100 ÷ 500 = 0.20 lots.
Check it: 0.20 lots × 50 pips × 10 USD = 100 USD. Tighten the stop to 25 pips and the same risk allows 0.40 lots. Widen it to 100 pips and it allows 0.10 lots. A wider stop means a smaller position, not a bigger risk.
Common mistakes
What mistakes do traders make when sizing a trade?
The usual mistake is choosing the lot size first and fitting the stop around it. Others include moving the stop after sizing, ignoring that fills can be worse than the stop price, and opening several correlated trades that each carry the full risk.
- ✓ Picking a lot size you like, then placing the stop wherever the maths works.
- ✓ Moving the stop further away after the trade is open without reducing the size.
- ✓ Assuming a stop-loss always fills at your price. In fast markets it can fill worse.
- ✓ Leaving out the conversion rate when the quote currency is not your account currency.
- ✓ Stacking trades that move together, so one event hits all of them.
Risk note. CFDs are leveraged products and losses can exceed your deposit, including when a stop-loss fills at a worse price. This calculator is a planning aid, not advice. Read the Risk Disclosure before you trade.
Keep learning
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