Position Sizing Math That Keeps You Under the Trailing Drawdown

Every failed evaluation has a moment where the math stopped working — usually two or three trades before the trader noticed. Position sizing is where funded accounts are won and lost, and the good news is that it's pure arithmetic. No prediction, no feel, no market read. Just numbers you can set once and respect forever.

Here's the sizing math that keeps you on the right side of the drawdown.

Start With the Only Number That Matters: Distance to the Floor

Forget the account size on the label. A "$50,000" evaluation with a $2,000 trailing drawdown is not a $50,000 account — it's a $2,000 account with big buying power. Your real capital is the distance between your current equity and your drawdown floor. Every sizing decision starts there.

The Core Formula

Risk a fixed fraction of your remaining drawdown per trade — most funded traders live between 5% and 10% of the distance to the floor.

Example: $2,000 trailing drawdown, risking 8% per trade = $160 of risk. Trading MES with a 10-point stop ($5 per point per contract = $50 risk each), that's 3 contracts. Trading ES with the same stop ($50 per point = $500 each), you can't even afford one — so you trade micros. That's not a downgrade; that's the math protecting you.

At 8% per trade, it takes 12 consecutive losses to fail. At 25% per trade, it takes four. Same strategy, same market — the sizing alone decides how much bad luck you can survive.

Recount After Every Trade

The trailing drawdown moves, which means your risk budget moves with it. After a winning day, your floor likely rose — the cushion you "made" partially isn't yours to spend. After a losing trade, your distance shrank and your next position should too. Sizing off Monday's cushion on Thursday is how traders fail with winning strategies.

The discipline: recalculate distance-to-floor before every session, minimum. Systematic traders recalculate before every trade — or better, have the system do it.

Respect the Daily Limit Inside the Math

Your per-trade risk also has to fit the daily loss limit. If the firm allows $1,000 per day and you risk $160 per trade, three losses put you at $480 — survivable. Risk $400 per trade and two losses have you one bad fill from a rule violation. A useful guardrail: size so that three full losers still leave you under 70% of the daily limit.

Where Sizing Plans Actually Die

Nobody breaks their sizing plan on a calm Tuesday. They break it after two losses ("I'll double to get it back"), after five wins ("I've earned bigger size"), and in the last week of an evaluation ("I just need one good trade"). The formula never fails — the finger on the order ticket does.

This is exactly why automated sizing beats willpower. A system holding your risk at 8% doesn't know what a losing streak feels like, and doesn't care how close the profit target looks. It just does the math — every trade, every time. Join the Push Button Trading community and put your sizing on autopilot before the market tests your discipline again.