Position Size Calculator
Professional traders size positions from risk, not conviction. Decide what percentage of your account you’re willing to lose if your stop is hit — this calculator converts that into an exact share count.
Most traders risk 0.5–2% per trade.
Shares to Buy
100
Dollar Risk
$250
lost if stop is hit
Position Value
$5,000
% of Account
20.0%
Position sizing formula
Shares = (Account × Risk%) / |Entry − Stop|Your maximum dollar risk divided by the per-share risk (distance from entry to stop) gives the share count that caps your loss at exactly your chosen risk.
How It Works
- 1First decide your risk budget — the dollars you accept losing if the trade fails.
- 2The distance between entry and stop is your risk per share.
- 3Dividing the two gives a share count where a stopped-out trade costs exactly your risk budget, no more.
Frequently Asked Questions
What percentage should I risk per trade?
The common professional range is 0.5–2%. At 1% risk, it takes 10 consecutive losses to draw down 10% — survivable. At 10% risk, three losses is a disaster.
Why is my position value larger than my risk?
Position value is what you invest; risk is only what you lose if the stop hits. A tight stop lets you control a large position with small risk — but tight stops get hit more often.
Does this work for shorts?
Yes — the formula uses the absolute distance between entry and stop, so it works in either direction.