Position Size Calculator

How big should your trade be?

Position sizing is the discipline that keeps one bad trade from blowing up your account. Instead of guessing how many shares or coins to buy, you decide how much money you're willing to lose on the trade, then work backwards to the size. This calculator does that math: it takes a fixed percentage of your balance as your risk, divides by the distance from entry to stop-loss, and gives you the exact position size.

The formula

• Amount at risk = balance × risk % (e.g. 1% of $10,000 = $100).
• Risk per unit = |entry − stop-loss|.
• Position size = amount at risk ÷ risk per unit.

The 1% rule

Many traders risk no more than 1–2% of their account per trade. At 1%, you could lose ten trades in a row and still have ~90% of your capital — leaving plenty of room to recover. Risking 10% per trade, three losses nearly halve your account.

FAQ

How is position size calculated?

It takes the amount you're willing to lose (your account balance times your risk percentage) and divides it by your risk per unit, which is the distance between your entry price and your stop-loss. The result is the exact number of shares, coins, or contracts to buy so that hitting your stop loses only your chosen amount.

What risk percentage should I use?

Many traders cap risk at 1–2% of their account per trade. At 1% you could lose ten trades in a row and still keep about 90% of your capital, whereas risking 10% per trade can nearly halve your account after just three losses.

Does it work for stocks and crypto?

Yes. The math is the same for any instrument priced per unit — stocks, ETFs, or crypto. For forex, where size is measured in lots and pip value matters, use the dedicated Lot Size Calculator instead.

Does my trading data stay private?

Yes. Your balance, entry, stop-loss, and risk settings are processed entirely in your browser and are never sent to a server or stored.

Is the position size calculator free?

Yes, it's free with no sign-up and works on mobile and desktop. It's an educational tool, not financial advice.

Educational tool only — not financial advice. For forex, use the Lot Size Calculator.