Fixed-fractional position sizing for challenge accounts
Risk a small, fixed percent of equity per trade so one loss cannot wreck your prop firm drawdown. Includes a simple sizing checklist.
Challenge accounts punish oversized risk. A 1% loss feels small on a personal account. On a $50k evaluation with a 5% daily cap, a few careless sizes end the week.
Fixed-fractional sizing means you risk the same percent of equity on every trade — usually 0.25% to 0.5% while you are in an evaluation. The stop defines distance. Size is what remains.
The formula (keep it boring)
Position size = (equity × risk %) ÷ (stop distance × value per unit)
Example: $50,000 equity, 0.5% risk ($250), 10-point stop, $5 per point → 5 contracts.
If the math says 5.4, take 5. Rounding up is how people quietly increase risk.
Tie size to the challenge, not the setup
A “high conviction” setup does not earn a larger fraction. Conviction is not a risk input. Your remaining daily loss and max drawdown are.
Before you size up for a breakout:
- Check remaining daily room with the prop firm drawdown calculator.
- Size the trade with the position size calculator.
- Confirm reward-to-risk still makes sense with the risk-reward calculator.
If any of those three fail, skip the trade.
What “good” looks like after 30 trades
- Risk percent barely moves session to session.
- Losers look similar in dollar terms.
- You rarely feel surprised by how much a stop cost.
That boring pattern is the point. It keeps you alive long enough for expectancy to matter.
Next step
Pick a fixed risk percent for this challenge week. Use the position size calculator on every entry until the habit sticks — then track the same risk process in TradeKeel so your journal matches what you actually risked.