How to calculate position size
Risk Amount = Account Balance × Risk % Stop Distance = |Entry − Stop| Position Size = Risk Amount / Stop Distance (in units) Position Value = Position Size × Entry (in USD)
If your entry equals your stop, there is no stop distance to size against — the calculator stays blank.
Worked example. Account of $10,000, risking 1% per trade. You want to long ETH at $3,000 with a stop at $2,880.
Risk Amount = 10,000 × 0.01 = $100 Stop Distance = |3,000 − 2,880| = $120 Position Size = 100 / 120 = 0.833 ETH Position Value = 0.833 × 3,000 = $2,500
Buy 0.833 ETH (about $2,500 of exposure). If the stop triggers, you lose $100 — exactly 1% — no matter how the trade felt going in.
- •Decide what you are willing to lose on the trade — a percent of your account is cleaner than a fixed dollar.
- •Multiply your balance by that percent to get the risk amount in dollars.
- •Find the distance between your entry and your stop-loss.
- •Divide the risk amount by the stop distance. The result is your position size in units.
Why it matters for your trading
Almost every account that gets wiped out dies the same way: a position too large for its stop, held through a move that should have cost 1% but cost 20% because the size was set by gut feel instead of arithmetic. Sizing from risk first inverts that. The stop defines the loss, the loss defines the size, and the size adapts automatically to volatility — a wide stop on a choppy alt gives you a small position, a tight stop on a clean setup gives you a larger one, and both risk the same dollar.
This pairs directly with the risk-reward calculator: size sets what you can lose, R:R sets what you stand to gain, and together they make every trade a known quantity before you click.