Position Size Calculator
Calculate how many units to trade based on your account size, the percentage you're willing to risk, and the distance from entry to stop-loss.
Calculator
Formula
- Risk amount = Account size × (Risk % ÷ 100)
- Per-unit risk = |Entry price − Stop price|
- Units = Risk amount ÷ Per-unit risk
- Position value = Units × Entry price
How it works
Position sizing is the process of deciding how large a trade should be so that a single losing trade only costs a pre-defined, acceptable fraction of your account. It separates the question of "how much to trade" from the question of "where to enter".
The method here is fixed-fractional risk: you choose a percentage of the account to put at risk, then derive the quantity from the distance between your entry and your stop-loss. A wider stop means a smaller position for the same dollar risk; a tighter stop means a larger one.
Consistent sizing is a core risk-management discipline. This calculator performs arithmetic only — it does not tell you what to trade, when to trade, or whether any trade is a good idea.
Example use cases
Tight stop on a $10,000 account
Account $10,000, risk 1%, entry $100, stop $95 → risk $100, per-unit risk $5, so 20 units ($2,000 position).
Wider stop, same risk
Same account and 1% risk but stop at $90 → per-unit risk $10, so only 10 units ($1,000 position) for the identical $100 risk.
Frequently asked questions
What risk percentage should I use?+
That is a personal risk-management decision, not something a calculator can answer for you. Many educational sources discuss small fixed fractions (often cited as 0.5%–2%) to limit the impact of any single loss, but the right value depends entirely on your own circumstances and risk tolerance.
Does this account for leverage or margin?+
No. It returns the number of units and the notional position value. Whether you can hold that position depends on your broker's margin requirements — see the Margin Calculator.
Why does a wider stop reduce my position size?+
Because dollar risk is held constant. If each unit can lose more before hitting the stop, you must hold fewer units to keep total risk at the same amount.