The rule that ends most attempts is rarely the profit target
Everyone looks at the target first. In practice the attempts that fail almost always end at a loss rule — the drawdown floor or the daily limit — long before the target is out of reach. That is what our prop firm daily loss limit study found on three real strategies: moving the daily limit across its normal range swung the pass rate about as much as moving the target, and you choose the daily limit when you choose the firm. The calculator shows the same thing for your own numbers. Change the drawdown by a few hundred dollars and watch how far the pass probability moves; then do the same with the target.
Then try the honest test: halve your average trade. A backtest's average is an estimate, and it is usually on the optimistic side. If the pass probability collapses, the evaluation is a bet on that estimate being right.
How the simulation works
- Trades. Each trading day takes the number of trades you enter; a fraction such as 2.5 means every other day has one extra. Each trade wins with your win rate. A win pays the average win and a loss costs your average losing trade. The average win is not an input — it follows from the other three, because average trade = win rate × average win − loss rate × average loss.
- Fixed or variable sizes. "Fixed" suits a strategy with a hard stop and target. "Variable" draws every win and loss from an exponential distribution with the same average, so the averages are unchanged but about one loss in twenty is three times the average or more — closer to a strategy that holds through gaps.
- The drawdown floor is checked after every trade. Static: the starting balance minus the maximum drawdown, forever. End-of-day trailing: the highest closing balance minus the drawdown, moved once a day at the close. Intraday trailing: the highest balance after any trade minus the drawdown. With the box ticked, a trailing floor stops rising once it reaches the starting balance.
- The daily loss limit is measured from the day's starting balance. "Fails the attempt" ends it on the spot. "Ends the day only" closes you out at the limit — the loss is capped there, like an automatic liquidation — and trading resumes the next day.
- Passing needs the profit target and, if there is one, the consistency rule: your best day must be no more than the chosen share of total profit. If you hit the target with one big day, you keep trading until profit has grown enough. If the target comes before the minimum trading days, the remaining days are counted as done with minimal trades, which is how most traders handle it.
- Precision. 10,000 attempts with a fixed random seed, so the same inputs always give the same answer. The ± figure is the 95% sampling range of those 10,000 attempts — it says nothing about how good your inputs are.
What the calculator can't know
It treats every trade as independent, and real markets don't work that way. Losing streaks cluster in volatile weeks, and the clustering is exactly what kills evaluations: when our FTMO simulation walked a real 23-year return sequence through the rules instead of random trades, five crash days decided most of the failures. A firm's intraday trailing floor also follows your open profit, which a closed-trade model can't see, so for intraday trailing accounts the real floor is higher than the one simulated here. Both effects point the same way: treat the number as an upper bound, and see the Monte Carlo drawdown article for how deep a normal bad stretch can go.
Download a free strategy
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FAQ
How is the prop firm pass probability calculated?
The calculator runs 10,000 simulated evaluations. Each trade wins with your win rate; a win pays the average win and a loss costs your average losing trade. The average win follows from your average trade, win rate and average loss. The firm's rules are checked after every trade, and the pass probability is the share of attempts that reach the target without breaking a rule. A fixed random seed means the same inputs always give the same answer.
What is the difference between a static, end-of-day and intraday trailing drawdown?
A static drawdown is a fixed floor: the starting balance minus the maximum drawdown. An end-of-day trailing drawdown moves the floor up to the highest closing balance minus the drawdown, once per day. An intraday trailing drawdown moves it after every new high during the day. Most futures firms stop trailing once the floor reaches the starting balance. Trailing floors are stricter because a winning streak raises the floor you can later fall to.
How does a prop firm consistency rule work?
A consistency rule caps how much of your profit may come from your single best day — for example, no day may be more than 50% of total profit when you pass. In this calculator it does not fail an attempt: if your best day is too large, you keep trading until total profit has grown enough, which keeps you exposed to the drawdown and daily rules for longer. Some firms define the rule differently, so read your firm's wording.
Can I use this calculator for Apex, Topstep or FTMO rules?
Yes. Enter the numbers from the firm's current rules page: account size, profit target, the drawdown and how it trails, the daily loss limit and whether breaking it fails the account or only ends the day, and the consistency rule. The presets are generic versions of the common formats — a 50K futures evaluation with an end-of-day or intraday trailing floor, and the two-step challenge used in our FTMO simulation. Firms change these rules often, so check them on the day you buy.
Why might my real pass rate be lower than the calculator says?
The simulation treats every trade as independent. Real losing streaks cluster in volatile weeks, real intraday trailing floors follow open profit rather than closed trades, and a backtest's average trade is an estimate that is usually too optimistic. Each of those lowers the real pass rate. Try your numbers again with half your average trade.
