Position size calculator for stocks and crypto
Choose how much of your account you are willing to lose if the stop-loss is hit. The calculator returns the number of shares or coins that matches that risk.
How it's calculated
- Amount at risk = balance × risk %. 10,000 × 1% = $100.
- Risk per unit = |entry − stop-loss|. Entry 50, stop 48: $2 per share.
- Units = amount at risk ÷ risk per unit, rounded down to the size step. $100 ÷ $2 = 50 shares, worth 50 × $50 = $2,500.
- Crypto example: 10,000 × 2% = $200; entry 60,000, stop 58,500 → $1,500 per coin; 200 ÷ 1,500 = 0.13333 → 0.133 with a 0.001 step, worth $7,980.
Questions
Why is the size rounded down?
Rounding up would make the loss at the stop slightly larger than the risk you chose. Rounding down keeps it at or below that amount.
Does it work for short positions?
Yes. Put the stop-loss above the entry price; the size is calculated the same way from the distance between them.
Why can the position value be larger than my balance?
With a tight stop the risk per unit is small, so many units fit the same risk amount. Opening such a position needs leverage or margin; the calculator warns you when that happens.
Are fees included?
No. Commissions and the spread add to the loss if the stop is hit. To stay within your risk, use a slightly smaller risk % or a size step below the result.
Can I use it for currency pairs?
Currency pairs are traded in lots, and the value of a price move depends on the pair and your account currency. This calculator is meant for shares and coins, where one unit moves by exactly the price change.