Prop Firm Challenge Math: Pass Odds, Fees and Losing the Funded Account

A prop firm challenge means paying a fee to trade an evaluation account under set rules. Reach the profit target without hitting a loss limit and you get a funded account, an account the firm lets you trade, with profits split between you. It sounds like a shortcut for traders with small capital, but the rules form a maths problem that can be answered. This article simulates how the chances of passing, failing and running out of time depend on edge and risk per trade, then looks at what happens after you pass. It does not recommend any firm.

The usual rules

The figures below are common shapes, not a standard. Every firm differs, and terms can change.

Rule	Common shape	What to check in the terms
Profit target	8% to 10%; some have two phases, the second around 5%	Measured on balance or equity
Max daily loss	5%	5% of the starting balance or of the day’s opening balance; floating trades included; reset time
Max overall drawdown	10%	Fixed from the starting balance (static) or following the peak (trailing)
Minimum trading days	A few days	Whether a day counts only if you open a trade
Time limit	30 days or unlimited	Calendar days or trading days
Fee	Paid on every new attempt	Refunded with the first payout or not
Profit split	Most to the trader, e.g. 80%	Payout cycle, minimum profit, rules that block payouts

Balance versus equity matters a lot. If the limit is measured on equity, a floating loss that touches it fails you on the spot, even if price later comes back. See the difference in How to read drawdown.

Simulation setup

• One phase: target +10%, daily limit 5% of the starting balance measured from the day’s opening balance, max drawdown 10%, at least 4 trading days, 30 trading days allowed
• Up to 3 trades a day, fixed risk as a % of the starting balance, a loser costs exactly 1R, a winner makes 2R, trades independent of each other
• Edge system, wins 40% at 2R: 0.4 × 2 − 0.6 = +0.2R per trade (a very strong edge for a retail trader)
• No-edge system, wins 1 in 3 at 2R: 0R per trade. Same shape, just no edge
• The trader stops for the day if one more loss would hit the daily limit; once the target is reached they stop risking and wait out the minimum days
• Closed trades only, no slippage, no gaps through the Stop loss, 100,000 runs per case. Every number here is simulated, not real trading

This setup is kinder than reality, which has floating losses, costs and days when price jumps.

Pass, fail or time out, by risk per trade

Risk per trade	Edge: pass	Edge: fail	Edge: time out	No edge: pass	No edge: fail	No edge: time out
0.25%	8.3%	0.0%	91.7%	0.3%	0.2%	99.5%
0.5%	56.3%	1.1%	42.6%	13.8%	13.0%	73.2%
1%	81.6%	11.6%	6.8%	42.2%	43.1%	14.7%
2%	71.6%	28.3%	0.1%	48.4%	51.5%	0.1%
3%	67.7%	32.3%	0.0%	48.0%	52.0%	0.0%

A simple way to see why low risk times out. The +0.2R system at 0.25% risk makes 0.2 × 0.25% = 0.05% per trade on average; at 3 trades a day that is 0.15% a day, so reaching the target takes 10 ÷ 0.15 ≈ 67 trading days on average, far beyond 30. The no-time-limit simulation agrees: passing runs took 67.8 days on average, and 100.0% passed (fewer than 0.05% failed). At 1% the average is 0.6% a day, about 10 ÷ 0.6 ≈ 17 days, which fits inside the window.

The incentive to over-risk

Look at the no-edge side. The more it risks, the more often it passes: from 0.3% at 0.25% risk to 48.4% at 2%. The reason is distance.

• At 1% the target is 10R away and the limit is 10R away
• At 2% both sides shrink to 5R
• In a game with no edge, when both sides are equally far, which one you reach first is close to 50:50, as in gambler’s ruin. The no-time-limit simulation gives 50.0% at 0.25% and 49.3% at 1%

Higher risk adds no edge. It only makes the result arrive before the clock runs out. Rules with a time limit therefore reward high risk the same way a bet does. The edge system benefits from higher risk only up to a point: it passes most often, 81.6%, at 1%, then drops to 71.6% at 2%, because a run of five or six losses, which is normal, is already enough to hit the limit.

Compare with the Kelly criterion. A system winning 40% at 2R has a Kelly size of 10% per trade, but a 10% drawdown limit makes the size that actually works far smaller, around 10 to 20 times smaller. A formula that knows nothing about the limit can’t be applied to a challenge directly.

One pass is the result of a few dozen trades. A system with no edge passes 42.2% of the time at 1% risk, so a pass says as much about luck as about skill.

The daily limit: stop yourself or get stopped

Compare with a trader who doesn’t stop and takes all 3 trades every day, even after losses. At 2% risk, 3 losses in one day = −6%, which breaks the daily limit at once.

2% risk per trade	Stops before the limit	Doesn’t stop, trades every day in full
Edge +0.2R: pass	71.6%	46.5%
No edge: pass	48.4%	30.0%

At 1% the two are almost identical, since 3 losses = −3%, short of the limit. The daily rule catches traders who risk a lot per trade and keep going after losing, which is revenge trading. How to set your own limit below the rule’s limit is covered in Daily loss limit.

Trailing drawdown is harder than it looks

With a static drawdown the limit stays at the starting balance −10%. With a trailing drawdown the limit moves up with the account’s peak: reach +8% and the limit climbs to −2% from the starting balance. Some firms stop the trailing once the limit reaches the starting balance; some trail intraday equity, which is stricter than this simulation.

Risk per trade (30 days)	Static: pass	Static: fail	Trailing: pass	Trailing: fail
Edge, 0.5%	56.3%	1.1%	56.0%	3.2%
Edge, 1%	81.6%	11.6%	74.8%	23.5%
Edge, 2%	71.6%	28.3%	60.7%	39.3%
No edge, 1%	42.2%	43.1%	37.6%	59.5%

A balance-based trailing limit, as simulated here, measures drawdown from the peak, which is far easier to hit than a fall from the starting balance. A system that rises first and then pulls back normally can fail while the account is still in profit.

How many attempts, and what the fees add up to

If you retry until you pass and each attempt is independent, the average number of attempts = 1 ÷ pass rate. Assume a fee of 500 dollars per attempt (a made-up number for the calculation; real prices vary by account size and firm).

System, risk per trade	Pass rate	Average attempts	Average total fees
Edge, 0.25%	8.3%	12.0	about 6,020
Edge, 1%	81.6%	1.2	about 610
No edge, 0.5%	13.8%	7.2	about 3,620
No edge, 1%	42.2%	2.4	about 1,180
No edge after costs, 1%	31.7%	3.2	about 1,580

Example for the 1% edge row: 1 ÷ 0.816 = 1.23 attempts × 500 = 613 dollars. “After costs” is the no-edge system losing 0.05R per trade on average to spread and commission, simulated as the win rate dropping from 33.3% to 31.7%. That is closer to most traders’ reality than 0R. More on per-trade costs in What spread really costs.

With two phases (phase two targets +5% under the same rules), the chance of passing both is the product. Simulated at 1% risk: edge 73.2%, no edge 27.0%, no edge after costs 17.3%.

After passing, the account still has to survive

The simulation continues after a pass: a funded account with the same rules but no target. Every 20 trading days, if there is profit, the trader withdraws an 80% share and the account goes back to the starting balance, with the −10% limit unchanged. Example: on a 100,000-dollar account, a 4% profit this cycle = 4,000; the trader gets 4,000 × 0.8 = 3,200 and the account starts the next cycle at 100,000.

System, risk per trade	Lost within 60 trading days	Lost within 240 trading days	At least one payout
Edge, 0.5%	3.2%	15.1%	98.3%
Edge, 1%	29.6%	76.6%	87.4%
Edge, 2%	70.2%	99.3%	65.7%
No edge, 1%	77.9%	99.8%	50.1%
No edge after costs, 1%	87.4%	100.0%	37.4%

The edge system at 1% passes the challenge most easily, yet loses the funded account within 240 trading days 76.6% of the time. Profit is withdrawn every cycle, so the cushion stays at 10R. The Risk of ruin article found that the same system has a 95th-percentile drawdown of about 28R over 500 trades, so a 10R limit gets touched sooner or later. The risk that helps you pass and the risk that keeps the account alive are different numbers.

Combining both stages, the chance that one attempt leads to at least one payout (pass × ever paid): edge at 1% about 71.3%, no edge at 1% about 21.1%, no edge after costs at 1% about 11.9%. So a trader with no edge after costs walks away with nothing for the fee in almost 9 attempts out of 10.

The challenge rewards high risk over a short time. The funded account rewards low risk over a long time. Traders who use the same approach for both usually lose one of them.

The business model, and what to check before paying

From the numbers above, most traders with no edge after costs fail the challenge or lose the funded account within a few months, so their fees can be a major part of this kind of business’s revenue. That doesn’t mean every firm is a scam, but it does mean the firm’s interests are not always tied to your success. General points to know:

• Some firms state in their terms that funded accounts are simulated and that payouts come from the company, not from orders sent to a real market. Their ability to pay then depends on the company’s finances
• Firms in this industry have closed or stopped paying suddenly before, and many are not supervised the way brokers are
• Rules that can disqualify you or block a payout: no trading around news, no holding over the weekend, consistency rules that cap the share of profit from a single day, bans on some EAs or on copying signals
• Terms can change. Keep a copy of the terms on the day you sign up

The warning signs in Forex scam red flags apply here too, such as marketing built on the payout screenshots of a few, and pressure to sign up with limited-time discounts. If someone sells signals or an EA “for passing challenges”, check them the way you would in Evaluating copy trading and signals.

How to use these numbers

1. Prove the edge first with several hundred trades on your own account, after costs. Don’t use a challenge as the test
2. Translate the rules into R. A 10% limit at 0.5% risk = 20R. Compare it with your system’s 95th-percentile drawdown in R
3. Choose rules with no time limit if available. You can then use low risk without rushing. In the simulation, the edge system at 0.5% risk passed 98.1% of the time with no time limit
4. Set your own daily limit below the rule’s, and count floating trades too
5. After passing, lower your risk, or leave some profit in the account as a cushion if the terms allow
6. Set a total fee budget of money you can lose entirely, and don’t retry to win it back. Work out the lot size for the risk you choose with Position size from Stop loss

Common mistakes

• Believing a pass means skill. A no-edge system passes 42.2% of the time at 1% and 48.4% at 2%
• Raising risk as time runs out. It turns the game into a coin toss and pushes you towards the daily limit
• Not checking whether the limit is on balance or equity. A floating loss that touches the limit can fail you before the trade is closed
• Using challenge-level risk on the funded account. 1% risk passes most easily, but lost the account within 240 trading days 76.6% of the time in the simulation
• Retrying straight after failing. Total fees grow fast, and it follows the same pattern as revenge trading
• Looking only at the profit split, not at the rules that block payouts. An 80% split means nothing if you are disqualified before the payout date