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Position Size Calculator
Calculate planned position size from your balance, risk percent and stop in pips. It rounds down to your broker's lot step under the entered assumptions; fees, slippage and gaps can increase actual losses.
Position size is the lot size corresponding to a planned risk amount if the stop fills at the assumed price. In lots it is (account balance × risk%) ÷ (stop-loss in pips × pip value per lot). On a $10,000 account risking 2% with a 50-pip stop and a $10 pip value, that is 200 ÷ 500 = 0.4 standard lots. Always round down to your broker's lot step to keep planned stop risk within budget. This excludes fees, slippage and gaps and does not guarantee a maximum actual loss.
Your risk
Position to take
| Lot tier | Size |
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How it works
What position sizing does
Position sizing flips the usual question around. Instead of guessing a lot size and seeing what happens, you set a planned stop-risk budget for the trade and let the math return the size that produces exactly that risk. It is the single biggest lever a trader controls.
The formula
risk amount = account balance × (risk% / 100)
lots = risk amount ÷ (stop-loss in pips × pip value per lot)
The pip value per lot must already be in your account currency. For most USD-quoted pairs on a USD account that is $10 per standard lot; for cross pairs, get the exact figure from the Pip Value Calculator first.
How to use this calculator
- Enter your account balance and the percentage you are willing to risk on this trade.
- Enter the distance from entry to stop-loss, in pips.
- Enter the pip value per standard lot in your account currency.
- Set your broker's smallest lot step — the result is rounded down to it.
Worked example 1 — the 2% rule
A $10,000 account risking 2% can lose $200. With a 50-pip stop and a $10 pip value, the per-lot risk is 50 × 10 = $500, so 200 / 500 = 0.4 standard lots (40,000 units). If the stop fills at the assumed price, the gross planned loss is $200 before fees or slippage.
Worked example 2 — a smaller account
A $5,000 account risking 1.5% can lose $75. With a 25-pip stop and a $10 pip value, per-lot risk is $250, so 75 / 250 = 0.30 lots. Tightening the stop to 25 pips lets you trade a larger size for the same dollar risk.
When position sizing matters
It matters most when your stop distance changes from trade to trade. A fixed lot size means a tight-stop trade and a wide-stop trade carry very different dollar risk; sizing from risk keeps planned stop risk consistent, which is what makes a strategy's expectancy meaningful.
Common mistakes
- Rounding up. Rounding the lot size up pushes your real risk above plan. This tool always rounds down to your lot step.
- Using the wrong pip value. On a cross-currency account the pip value is not $10 — compute it first, otherwise the size is wrong.
- Ignoring spread and slippage. Your real loss is the stop distance plus spread and any slippage; size with a small buffer if your stop is tight.
Frequently asked questions
How do I calculate forex position size from risk percent?
(balance × risk%) ÷ (stop pips × pip value).What lot size should I trade on a $10,000 account?
Why does the tool round the lot size down?
How much should I risk per trade?
Do I use the same pip value for every pair?
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