How the simulator works
Risk per trade is a fixed share of the starting balance; R is the risk of one trade in money. A trade makes +b R with probability equal to the win rate (the share of winning trades), or −1 R otherwise, and trades are independent. The phase is passed once profit from the start reaches the target; it fails when the loss from the start touches the max loss limit or the day's loss touches the daily limit.
Result = Risk × (b × Wins − Losses)— as a percentage of the start. At 1% risk and b = 1.5, an 8% target is, for example, 8 winners and 4 losers: 1 × (1.5 × 8 − 4) = 8%.Expectancy = Win rate × b − (1 − Win rate)— in R per trade: 0.45 × 1.5 − 0.55 = +0.125 R.
The simulator does not play out random trades — it calculates exactly: after each trade it carries the probabilities of every account state over to the next one (a Markov chain), and paths that reach the target or a limit drop out. So the same inputs always give the same numbers. The median is the trade by which half of the passing attempts have reached the target; the average attempt length counts fails too.
Check it against the example
The simulator opens with the example from «How to pass a prop firm challenge: rules and risk» — an 8% target, a 10% limit, a 45% win rate, 1.5 R wins and 1% risk — and, like the article, shows 85.4% and a median of 32 trades; why, and how to choose the risk, is explained there.
Daily limit and time limit
The daily limit here is a percentage of the starting balance, the day's loss counts from equity at the start of the day, and you take exactly the given number of trades a day. If even a day of nothing but losing trades cannot reach the limit, it does not affect the chance: at 1% risk and 4 trades a day a 5% limit is out of reach. At 5 trades a day and a 3% limit, the article's inputs give 36.9% instead of 85.4%.
The time limit is set in trades — estimate how many you will actually take within the program's deadline. Attempts that reach neither the target nor a limit are shown separately: with the article's inputs and a 30-trade limit, 39.3% of attempts reach the target in time and 55.7% run out of time.
The max loss limit here is static — from the starting balance. How it differs from a trailing one that follows the account's peak is in «Trailing vs static drawdown: what's the difference», and how daily and overall limits work is in «Prop firm risk management: daily limit and drawdown». Every program has its own rules and numbers — plug in yours.
How Davinchu keeps the phase parameters
Set the risk that gives you an acceptable chance in the Davinchu risk manager — together with «Max trades per day», «Daily stop-loss, %» and «Max drawdown, %», stricter than the firm's rules. The T-Manager EA for MetaTrader 5 (from the Plus plan) counts loss and the number of trades across the whole account, including manual trades and other EAs. With the default action «Warn at 70% and 90%, close new entries at 100%» it will not send an order without a stop loss or with risk above «Risk per trade, % (max)» of the balance, and at 100% of a limit it closes new entries through its panel: for the daily stop-loss and the trade count — until the end of the day, for drawdown — beyond that, until it falls below the limit. The day follows the time zone of the risk manager's «Trading hours» block (UTC if it is not set). T-Manager measures drawdown from the equity peak, so it is stricter than the firm's static limit.
Mark the prop account itself in the account settings: the «Prop Firm» mode, «Stage», «Profit target, %», «Daily loss limit, %» and «Max loss limit, %» — percentages of the starting balance, with the daily loss counted from midnight in your time zone. The account page then shows a «Prop account» block: how far you are from the target and how much room is left before the limits. What off-plan trades cost you is shown by «Cost of violations» on the journal's «Review» tab. More on the «Davinchu for prop traders» page.