Position Size Calculator
Calculate how much to buy based on your account size, risk tolerance, entry and stop-loss.
Calculator
For educational and informational purposes only — not financial, investment or tax advice. Results are estimates based on the figures you enter.
How the calculation flows
The inputs you enter feed a fixed formula to produce the result. Change any input to see how sensitive the outcome is.
Conceptual diagram
What the position size calculator does
The Position Size calculator tells you how large a trade to open so that, if your stop-loss is hit, you lose only a pre-set fraction of your account. It turns risk management from a vague intention into a number, and it is arguably the single most useful habit a new trader can build.
How it works
You decide the most you are willing to lose on one trade (your risk), and the distance between your entry and your stop-loss (your risk per unit). Dividing one by the other gives the largest position that respects your limit.
Worked example
Illustrative example — your figures will differ
A $10,000 account risking 2% per trade, entering at $100 with a stop at $90 (the calculator’s defaults).
- Most you’ll lose if stopped out: 2% × $10,000 = $200
- Risk per unit: $100 − $90 = $10
- Position size: $200 ÷ $10 = 20 units, a $2,000 position
A tighter stop allows a larger position
For the same $200 risk budget, the closer your stop sits to your entry, the more units you can hold — and the more a sudden move stings if the stop is too tight to survive normal noise.
| Entry → Stop | Risk / unit | Units | Position size |
|---|---|---|---|
| $100 → $98 | $2 | 100 | $10,000 |
| $100 → $95 | $5 | 40 | $4,000 |
| $100 → $90 | $10 | 20 | $2,000 |
| $100 → $80 | $20 | 10 | $1,000 |
How to use it
- Enter your account size and the risk per trade you are comfortable with (1–2% is a common starting point).
- Enter your planned entry and stop-loss prices.
- Read the position size and the amount at risk, then place the stop where it belongs technically — not where it gives you a bigger position.
Limits to keep in mind
- Slippage and gaps can fill your stop worse than planned, so real losses may exceed the budget.
- It sizes a single trade; managing risk across correlated positions is a separate discipline.
- Leverage multiplies both the position and the speed at which a stop is hit.
Related reading
- Glossary: Volatility and Slippage
- Guide: How to Read a Crypto Market
- Related tool: Profit / Loss Calculator
For education only — not financial or investment advice. Sizing a trade does not remove the risk of loss.