Ask blown prop traders what killed their evaluation and most will mumble something about 'the drawdown.' The cruel irony: the drawdown rule is published on page one of every firm's rulebook. Traders fail it anyway because they never internalized the difference between static and trailing models — or how trailing drawdown quietly tightens the noose as equity peaks rise.

This guide breaks both models down with concrete numbers on a $100K account, shows you how to compute your real-time room on every trade, and gives you the sizing framework that makes drawdown breaches mathematically unlikely.