Free tool
Lot size calculator
Size every trade from your risk, not from a feeling. Forex, gold, silver, indices and Bitcoin, for MetaTrader 5.
The maths
How the lot size is calculated
1. Amount at risk = balance × risk %. With $10,000 and 1%, that is $100.
2. Loss per lot at the stop = contract size × stop distance. For pairs where USD is the base currency (USDJPY, USDCHF, USDCAD) the result is divided by the current price to convert it to dollars.
3. Lot size = amount at risk ÷ loss per lot, rounded down to the 0.01 lot step, so the real risk never exceeds your limit.
Example: gold, $10,000, 1%, stop $5.00 away. One lot of 100 ounces loses $500 at the stop, so the size is $100 ÷ $500 = 0.20 lots.
Questions
Frequently asked
What is a lot size calculator?
It turns a risk rule into a trade size. You enter your balance, the percentage you are willing to lose if the stop loss is hit, and the distance to the stop. The calculator returns the lot size that loses that amount, no more, at the stop.
How much should I risk per trade?
Many traders risk between 0.5% and 2% of the balance per trade. A lower figure means slower growth but a much smaller chance of a deep drawdown. Prop-firm challenges with a daily-loss limit usually need the lower end of that range.
Why does the result differ from my broker?
Contract sizes are not the same at every broker, especially for indices, metals and crypto. Check the contract size in MetaTrader 5 (right-click the symbol in Market Watch, then Specification) and type it into the contract size field.
Does it include spread and commission?
No. The result covers the loss at the stop-loss price only. Spread, commission, swap and slippage come on top, so on small stops round the lot size down rather than up.
Can I use it for a non-USD account?
The calculator assumes an account in US dollars. For another account currency, convert your balance to USD first, or use the result as a close estimate.
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