Lot size calculator: from money at risk to a size your broker accepts
Turn the money you are willing to lose and your stop distance into a lot size, rounded down to the volume step. Includes the three broker settings that override your answer.
You already know the money you are willing to lose and where the stop goes. This turns those two into a lot size your broker will accept. Runs in your browser, no live data, nothing is sent anywhere.
Lot, mini, micro
| Name | Written | Units | Pip value, USD pairs |
|---|---|---|---|
| Standard | 1.00 | 100,000 | $10.00 |
| Mini | 0.10 | 10,000 | $1.00 |
| Micro | 0.01 | 1,000 | $0.10 |
| Nano | 0.001 | 100 | $0.01 |
The formula
Lots = (money at risk ÷ stop in pips) ÷ pip value per lot
$50 risk, 40 pip stop, EUR/USD on a dollar account: $50 ÷ 40 = $1.25 per pip. $1.25 ÷ $10 = 0.125 lots. Rounded down to a 0.01 step: 0.12 lots, real risk $48.
Three broker settings that override your answer
- Minimum volume, usually 0.01. Below it the order is simply rejected.
- Volume step, usually 0.01. It is why 0.125 becomes 0.12.
- Contract size, 100,000 for currency pairs but often 100 for gold. A “1.00 lot” of gold is not the same money as a “1.00 lot” of EUR/USD.
All three are in the symbol specification: right-click the symbol in your platform and open specification.
Why it always rounds down
Rounding up means trading more risk than you decided. On a large account the difference is trivial; on a small one it is not. With $50 of intended risk, rounding 0.125 up to 0.13 makes the real risk $52, which is 4% more than planned, every trade, forever.
Related
- Position size calculator: starts from balance and a risk percentage instead.
- Pip calculator: for the pip value input.
- Lots.
Frequently asked questions
What is the smallest lot I can trade?
Usually 0.01 on retail accounts, and 0.001 on some cent accounts. The exact minimum and the step between sizes are in the symbol specification in your platform.
Is one lot of gold the same as one lot of EUR/USD?
No. Contract size is 100,000 units for most currency pairs but often 100 ounces for gold, so the same lot number is a completely different amount of exposure.
Why does it always round down?
Rounding up trades more risk than you decided. With $50 of intended risk, rounding 0.125 up to 0.13 makes the real risk $52, on every trade.
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