Position sizing
Forex Position Size Calculator
Work out lot size from account balance, risk percentage and stop loss in pips, with cross-currency conversion from daily ECB rates.
How position size is calculated
Position sizing starts from the loss you are willing to take, not from the lot size you would like to trade. You decide what share of the account a single losing trade may cost, measure how far away your stop sits, and the position size follows from those two numbers.
risk amount = balance × risk % pip value/lot = pip size × 100,000 × (quote → account rate) lots = risk amount ÷ (stop pips × pip value/lot)
The pip size is 0.0001 for most pairs and 0.01 for pairs quoted in Japanese yen or Hungarian forint. A standard lot is 100,000 units of the base currency, a mini lot 10,000 and a micro lot 1,000.
Worked example
A USD account holds 10,000 and the trader risks 1% on a EURUSD trade with a 50-pip stop. The risk amount is 100 USD. EURUSD is quoted in dollars, so one pip on a standard lot is worth 0.0001 × 100,000 = 10 USD. The position is 100 ÷ (50 × 10) = 0.2 lots. If the stop is hit, the loss is roughly 100 USD before spread and slippage.
The same trade on USDJPY works differently because the pip is worth 1,000 yen per standard lot. The calculator converts that yen amount into dollars with the reference rate, so the pip value moves slightly every day even though the trade setup has not changed.
When the quote currency differs from your account
If you trade GBPJPY from a ZAR account, profit and loss arrive in yen and must be converted into rand. The calculator uses the European Central Bank reference rates published on 2026-10-01. They are end-of-day rates, not live quotes. For very tight stops, or during fast markets, enter the live conversion rate from your platform in the optional field.
What the number does not cover
- Spread and commission. Both add to the loss when a stop is hit. On a 10-pip stop, a 1-pip spread is a 10% increase in the real risk.
- Gaps and slippage. A stop is an instruction, not a guarantee. Weekend gaps and news releases can fill it well beyond the stop price.
- Correlated positions. Three trades risking 1% each on EURUSD, GBPUSD and AUDUSD behave more like one 3% bet on the dollar.
- Metals, indices and crypto. Contract sizes vary by broker. Use the contract specification in your platform instead of the 100,000-unit forex default.
Questions
How many lots can I trade with a 1,000 USD account?
It depends on the stop, not the account alone. Risking 1% (10 USD) with a 20-pip stop on EURUSD gives 10 ÷ (20 × 10) = 0.05 lots, or five micro lots.
Does leverage change my position size?
No. Leverage changes how much margin the broker holds, not how much you lose when the stop is hit. Position size should come from your risk amount and stop distance.
What is the 1% rule?
A common guideline that caps the loss on any single trade at 1% of the account. Ten consecutive losses then cost about 9.6% of the balance rather than a large share of it.
Why does my broker show a slightly different pip value?
Brokers convert with live rates, while this calculator uses the daily ECB reference rate unless you enter a live rate. The gap is usually small but grows on volatile days.