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Create AccountLot Size Calculator
Calculate the correct lot size from your account balance, risk percentage and stop loss.
Your Result
The calculation runs in your browser. Rates used for currency conversion are indicative — check your broker for the exact figure.
This calculator tells you how big a position can be before a losing trade costs more than you planned. Give it three numbers — your balance, the percentage you are willing to lose on this trade, and the distance to your stop in pips — and it returns the size in lots.
The logic is the one professional risk managers use: decide the loss first, then let the loss decide the size. Traders who size the position first and place the stop afterwards risk a different amount on every trade, which makes results impossible to measure.
When to use it
- Before every entry, once you know where your stop belongs.
- When you switch pairs — pip value differs, so the same stop needs a different lot size.
- When your balance changes, so risk stays proportional as the account grows or shrinks.
- On a prop firm challenge, where one oversized trade can breach the daily loss limit.
Two steps. First the money at risk, then the size that produces exactly that loss at your stop.
Risk Amount = Account Balance × Risk %
Lot Size = Risk Amount ÷ (Stop Loss in Pips × Pip Value per Lot)- EUR/USD, GBP/USD, AUD/USD, NZD/USD — $10 per pip on a 1.00 lot.
- JPY pairs — one pip is 0.01, so the value depends on the current rate.
- XAU/USD (gold) — a 1.00 lot is 100 ounces; taking $0.10 as one pip gives $10 per pip.
- If your account is not in USD, pip value is converted before the division. That conversion uses indicative rates — your broker will differ slightly.
A trader with a $10,000 account risks 1% per trade and wants to buy EUR/USD with a 50 pip stop.
Working: $100 ÷ (50 × $10) = 0.20 lots. If the stop is hit the loss is $100 — exactly the 1% planned. Widen the stop to 100 pips and the size halves to 0.10 lots, because the planned loss has not changed.
Why is my broker's lot size slightly different?
Brokers round to two decimals and use their own live pip value, which moves with the exchange rate. A difference in the third decimal is normal. Round down rather than up to stay inside your risk limit.
What risk percentage should I use?
Most risk plans sit between 0.5% and 2% per trade. Prop firm accounts usually need the lower end, because a daily loss limit can be breached by two or three normal losses in a row.
Does this include commission and spread?
No. The result is based on the stop distance alone. If your broker charges a round-turn commission, subtract it from your risk amount, or widen the stop slightly for the spread.
How do I calculate lot size for gold?
Select XAU/USD. Gold uses a 100 ounce contract, so the pip value and the resulting lot size are not the same as a currency pair with an identical stop distance.
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