How to use the prop firm challenge pass probability calculator
- Enter the account size and pick its currency. The size only sets the money amounts. The odds depend on the percentages.
- Enter the profit target and the maximum loss as percentages of the account, the way your firm states them.
- Choose the maximum loss rule. Static keeps the floor at the starting balance minus the maximum loss. Trailing moves the floor up behind your highest balance.
- Add the daily loss limit if there is one. Leave the field empty if the challenge has none.
- Set the time limit in trading days and the number of trades you take on a typical day.
- Enter your win rate, your reward to risk and your risk per trade. Take the first two from your own journal. They are only as good as the trades behind them, so use at least 100 trades if you can (see sample size).
The result updates as you type. The first number is the chance of passing. Under it, a bar splits the 2,000 simulated attempts into four outcomes, a line chart draws 40 of them day by day between the target and the floor, and a second chart shows how the pass chance changes with the risk you take.
How the pass probability is worked out
There is no neat formula for this, because a challenge has two walls and a clock. The calculator plays it out instead. Every attempt follows the same rules:
every trade: win with probability p → equity + R × risk
lose with probability 1-p → equity - risk
an attempt ends at the first of:
equity ≥ account × (1 + target) → passed
equity ≤ floor → failed, maximum loss
equity ≤ equity at the start of the day - daily limit
→ failed, daily loss
the last day has been traded → out of time
static floor = account - maximum loss
trailing floor = highest equity - maximum loss (never below the static floor)
pass probability = passed attempts ÷ 2,000
expected tries = 1 ÷ pass probability
edge per trade = p × R - (1 - p)
p is your win rate. R is your reward to risk, the average win divided by the average loss. Risk is a fixed amount of money, a percentage of the starting balance, the same on every trade. Challenges are usually traded that way, and it means the profits do not compound.
The draws come from a seeded random generator, so the same inputs always give the same answer and a shared link shows the same numbers to everyone.
Worked example
A 100,000 account has an 8% profit target, a static 10% maximum loss, a 5% daily loss limit and 30 trading days. You take 3 trades a day, win 45% of them at 1.5R and risk 0.5% of the account on each. Those are the figures the calculator opens with.
The edge is positive, yet only about one attempt in two passes. The reason is in the fifth and seventh rows: 90 trades at +0.125R average out to +5.6%, short of the 8% target. Passing needs a better than average run, and the clock cuts off the rest. The daily limit never fires because three trades at 0.5% can lose at most 1.5% in a day.
How to read the result
The percentage next to Passed is a simulation, not a measurement. With 2,000 attempts it is accurate to about two points either way, so 48% and 50% are the same answer.
Look at the other three outcomes before the pass chance. They tell you what to change:
- Mostly out of time means the edge is real but slow. More trades, a lower target or more days would help. Larger risk would too, but it moves attempts into the next category.
- Mostly maximum loss means the risk is large for the room you have. See the prop firm drawdown calculator for how many losing trades the floor allows.
- Mostly daily loss means a few bad days end attempts that would otherwise recover. Fewer trades a day or less risk on each fixes that.
Expected tries is one divided by the pass chance, the average number of attempts you would need before one passes, if each attempt were independent and you did not learn between them. Multiply it by the attempt fee to see what passing is expected to cost. A strategy with a 10% pass chance needs ten tries on average, and some people need many more.
Try the numbers with no edge, a 40% win rate at 1.5R. The average trade is worth exactly zero, and in this setup about 16% of attempts still pass, because a random walk with 90 steps reaches +8% before the clock runs out now and then. That is luck, not skill, and it is why a single pass tells you less than a series of results.
How risk per trade changes the odds
The second chart repeats the whole simulation at eight risk levels, from 0.25% to 3% per trade, and marks yours. With the example numbers it reads:
The chart runs 1,000 attempts at each level, so a point can differ by a point or two from the headline number at the same risk.
The curve rises and then falls, and the shape is the useful part. At low risk the target is too far away for the days you have, so attempts end on the clock. At high risk the target comes quickly, but losing streaks reach the floor or the daily limit. At 2%, the 5% daily limit becomes the main way to fail: 46% of attempts in the same simulation end that way.
Where the peak sits depends on every other input, and the model has no streaks or tilt in it. Real losing runs are longer and uglier than independent coin flips, so the sensible level in practice is lower than the top of the curve. Use the chart to see how fast the odds degrade, not to pick a number to bet.
A trailing floor makes the high-risk end worse, because every new high lifts the floor behind you. Switch the rule to trailing and the example at 1% risk drops from 77% to 73%, while the share failing on the maximum loss doubles from 12% to 23%. At 0.5% the difference is small. The trailing drawdown entry explains the rule.
Time limit, trades per day and the daily limit
The clock. With the same edge, 15 days passes about 16% of attempts, 30 days about 48% and 60 days about 78%. A challenge with no time limit is easier than one with 30 days, and a calculator that ignores the deadline overstates your odds. Enter the real number of days.
Trades per day. More trades give a positive edge more chances to show up. With 10 trades a day instead of 3, the example passes about 90% of the time. That only holds if the extra trades are as good as the first three. Most traders find their win rate falls as the count rises, a pattern covered under overtrading. Test the effect by lowering the win rate as you raise the trades.
The daily limit. The limit only matters if a day of losing trades can reach it. At 3 trades and 0.5% risk, the worst day is 1.5%, so a 5% limit is out of reach and the calculator says so. It begins to matter at 10 trades a day. With 10 trades and 1% risk, about 38% of attempts fail on the daily limit in the example. The daily loss limit entry explains how firms measure it.
Common pass probability mistakes
- Using a win rate from a few trades. Twenty trades say very little. A 45% win rate measured on 20 trades could easily be 30% or 60% in the long run.
- Entering your best reward to risk. Use the average over all your trades, including the ones where you moved the stop or exited early.
- Reading the pass chance as a promise. It is the answer to "if my numbers hold and my trades are independent". Both can fail.
- Raising the risk to beat the deadline. The risk chart shows the cost: the floor and the daily limit take over.
- Forgetting rules the model does not have. Minimum trading days, consistency rules and news restrictions all change what passing takes.
- Using one market's statistics for another. A win rate from a quiet session does not carry over to a volatile one.
What the calculator does not know
The simulation treats every trade as an independent draw with the same win rate and the same reward to risk. Real trading has streaks, because markets move in regimes and traders react to losses. It has costs: spreads, commissions, slippage and swaps all lower your edge, and they are not in the model. It has discipline lapses, such as revenge trading after a loss or skipping the stop, which are the most common reason a good edge fails.
It also does not know your firm. How the daily limit is measured, whether the floor follows balance or equity, whether the target is checked intraday or at the close, how many days you must trade and whether a consistency rule applies all differ between firms and change over time. Read your own firm's rules page, which is the only authority on your account.
The result is a model of the numbers you typed. It is not a prediction of your result and not investment advice.
Frequently asked questions
What is a good pass probability for a prop firm challenge?
There is no standard threshold, and a higher number is not automatically better if it comes from taking more risk than you can control. A pass chance of 50% or more with the failures spread across the clock and the limits is a reasonable sign that your edge and your risk fit the rules. Compare it with the pass chance you get when the edge is zero, which shows how much of the result is luck.
How do I calculate the chance of passing a prop firm challenge?
Simulate it. Give each trade your win rate and reward to risk, apply the target, the maximum loss, the daily limit and the deadline, and repeat thousands of times. The share of attempts that reach the target first is the pass chance. This calculator does exactly that, with 2,000 seeded attempts.
What win rate do I need to pass a prop firm challenge?
It depends on your reward to risk, the target and the time you have. At 1.5R the break-even win rate is 40%. With the example rules, 40% passes about 16% of the time, 45% about 48%, 50% about 80% and 55% over 96%. Run your own numbers, since a different target or deadline moves every one of these.
How many attempts will I need to pass?
On average, one divided by your pass chance. A 48% chance means about two attempts, a 10% chance about ten. This assumes the attempts are independent and that you do not change your approach between them, so treat it as a rough guide to cost.
Does a trailing drawdown lower my chance of passing?
Yes, and more as your risk rises. A trailing floor moves up with every new high, so the room you have shrinks as you win. In the example the difference is small at 0.5% risk and large at 1%, where failures on the maximum loss double. Switch between static and trailing in the calculator to compare.
Why does my pass chance fall when I risk more?
Because larger bets reach the floor or the daily limit sooner. Risk raises the speed at which you can reach the target, and it raises the chance of a losing run ending the attempt by about the same amount. Past a point the second effect wins, which is the downward slope of the curve.
Why is the daily loss failure 0%?
Because a full day of losing trades cannot reach the limit. Multiply trades per day by risk per trade: if the product is below the daily limit, the limit cannot fire. The calculator shows a note when this happens.
Does the calculator include spreads, commissions and slippage?
No. Those costs lower your real win rate or reward to risk, so build them into the inputs. If you know your average cost per trade in R, subtract it from your average win and add it to your average loss before you enter them.
Is the simulation a prediction?
No. It shows how your numbers behave under simple assumptions: independent trades, one fixed risk and no costs. Real results will be more uneven, so read the output as a stress test of your plan, not a forecast.