How do I calculate position size for a trade?
Divide maximum dollar risk (account balance × risk %) by per-unit risk (entry price minus stop loss per share or contract). The result is how many shares, units or lots to trade.
Position size calculator
Enter account size, risk %, and stop loss to get exact position size for stocks, forex, and crypto.
Free · no sign-up · Runs in your browser · Last updated 18 September 2026
The short version
Size the position from the stop, not from a fixed share count. Max dollar risk ÷ per-share risk = shares.
What is a position size calculator?
A position size calculator tells you how many shares, lots or contracts to trade from your account size, risk per trade (usually 1–2%) and stop distance. Active stock, forex and crypto traders use it before entry to cap dollar risk and size the position from the stop, not from a fixed share count.
The formula
- Maximum dollar risk
- account balance × risk %
- Risk per share
- | entry price − stop loss |
- Position size
- max dollar risk ÷ risk per share
Round down, never up — a partial share is not a rounding error you can afford on the stop. For forex, substitute lot size and pip value; for futures, contracts and point value.
Worked example
| Account balance | $25,000 |
|---|---|
| Risk per trade | 1% |
| Maximum dollar risk | $250 |
| Entry | $48.20 |
| Stop loss | $46.60 |
| Risk per share | $1.60 |
| Position size | 156 shares |
That's a $7,519 position on a $25,000 account — 30% of equity, risking 1%. The position looks large because the stop is tight; it's the stop that governs risk, not the position value.
Position sizing questions
What risk percentage should I use per trade?
Most professional traders risk 1–2% of account equity per trade. Risking more than 2% per trade increases drawdown depth and makes recovery harder.
Other free calculators
Sizing is the easy half. The hard half is checking whether you stuck to it.
TradeReview logs the size you actually took, flags oversized trades and missing stops in the Discipline report, and walks you through them in a Review Session. Free forever, no card.