Loss first, stake second. Decide what this trade is allowed to cost you, set the stop where the idea is wrong, and let those two numbers choose the stake — not confidence.
Tools
Position-size calculator
Maximum loss (your budget)£40.00
Stake per point£1.00
Notional exposure at that stake£10,650.00
Margin required (deposit)£532.50
Margin as share of account27%
Illustrative only. Stake is rounded down, never up — your risk budget is a ceiling. If the stop is hit with slippage, or you skip the stop, the loss exceeds the budget; only a guaranteed stop caps it exactly.
Reading the results
The formula is deliberately boring: maximum loss = account × risk %, then stake = maximum loss ÷ stop distance. A common rule is risking 1–2% per trade — at 2% you can be wrong twenty-five times in a row and still have three-quarters of your account. The margin figure shows what the provider will hold for the position; if it's a large share of the account, the position is big even when the planned risk looks small. The margin & P/L calculator shows the same trade from the exposure side, and the risk-management guide covers where stops belong: at the level that proves you wrong, never at a round number of pounds.