Size a trade by what you can lose

Most traders pick a size and then a stop. Turn it around: decide the dollars you are willing to lose, set the stop where the idea is wrong, and let the size follow.

1. Decide the risk per trade. A common rule is 1% of the account: $10 on $1,000.
2. In the ticket, choose Risk above the size and type the dollars. TP/SL switches on, since the size needs a stop.
3. Set the stop price. The ticket works out the size that loses exactly your dollars if the stop fills, and shows the position it makes.
4. Check the leverage: it decides the margin the position takes, not the risk.

The figure is the loss if the stop fills where you set it. In a gap at the open a stop can fill worse, which is why trading the night wants room.