Position size calculator

Work backwards from the loss

Most people pick a position size first and discover the risk afterwards. This runs the other way: decide what percentage of the account you are prepared to lose on one idea, decide where the idea is wrong, and the position falls out of those two numbers.

The consequence is counter-intuitive but correct — a tighter stop permits a larger position, because the same dollar risk is spread over a smaller price move.

Leverage shows up honestly

If the arithmetic produces a position larger than your account, the tool says it needs leverage rather than printing a figure that reads like a cash purchase. That is usually the point at which the stop is too tight for the volatility of the asset.

A stop is not a guarantee

In a fast market an order can fill well below your stop, and in a gap it may not fill anywhere near it. Crypto gaps more than most markets, particularly at weekends and during overnight liquidity gaps. Size assuming the loss can exceed the number shown.