The single number that separates traders who survive from traders who blow up — and how to actually enforce it.
The number that compounds
A trader risking 5% per trade needs to be right roughly 65% of the time just to break even after fees. A trader risking 0.5% can be right 45% of the time and still grow capital. That is not a difference in skill. That is a difference in arithmetic.
How to compute it, today
Take your account balance. Multiply by 0.005. That is your maximum dollar loss per trade. Divide by your stop distance in price units — that is your position size. If the math gives you a position smaller than the broker minimum, the trade is not for your account size yet. Wait, save, scale.
Why discretion kills the model
Every trader I have coached eventually wants to “size up the high-conviction one”. They are wrong, every single time. The one trade you sized up is the one that hits the unlucky stop. The model only works if you trust it most when you trust it least.
The journal closes the loop
Log every trade with planned risk vs. realised risk. If realised exceeds planned, flag it — that is the leak. Most blowups do not come from bad strategies. They come from sized-up losers, dressed up as conviction.