Watch the drawdown floor move.

What it reads

The rule your program uses, the starting balance, the drawdown limit, an optional level where the floor stops rising (many programs stop trailing at a set balance, so type it only if yours does), your risk per trade, and the results you type, one session per line. A result can carry the open peak it reached before it closed: 0.5(3) is a trade that was +3 R at its best and closed at +0.5 R.

How it is computed

Static: floor = starting balance − limit. It never moves. Worked example: $50,000 and a $2,000 limit put the floor at $48,000.00, whatever the results.

End-of-day trailing: at each session close, floor = max( floor, min( highest close − limit, lock ) ). Worked example: a session that closes at $50,500.00 moves the floor to $48,500.00 at the close. A later session that closes at $50,250.00 leaves it at $48,500.00.

Intraday trailing: during each trade, floor = max( floor, min( highest balance including open gains − limit, lock ) ). Worked example: a trade that is up $500 while open moves the floor to $48,500.00 at that moment. If it closes at −$250, the balance is $49,750.00 and the room is $1,250.00, not $2,000.

Where the floor stops rising. End-of-day trailing with the floor set to stop at $50,100: three sessions that each close $1,500 up move the floor to $49,500.00, then $50,100.00, and then leave it at $50,100.00.

Room in R = (balance − floor) ÷ risk per trade. Worked example: a balance of $50,125.00 over a floor of $48,875.00 is $1,250.00 of room, which at $250 a trade is 5.0 R: five full losses at your usual size.

A trade breaches when the balance after it is at or below the floor in force during it, and the results after a breach are not applied. In the 3× size example, trade 4 lifts the floor from $48,375.00 to $48,875.00 while it is open and takes the room from $1,750.00 to $500.00, and trade 6 reaches the floor.

Why that matters

The room you have is the distance to the floor, not to the starting balance, and under a trailing rule the floor follows your best point. Measured in R, the room says how many full losses at your usual size the account can take, which is the number a sizing decision actually changes: one trade at 3× size spends three of them, and under intraday trailing its open peak can spend more.

What it does not tell you

How your trades will go, or what your program’s rules are. It replays only what you type, it checks the balance at each trade’s close (a trade that went further against you before closing is not modelled), and it does not know your program’s daily loss limit, consistency rule or minimum days. Programs differ in exactly these details and change them: read your program’s own rules page. This is arithmetic, not advice.

What is the difference between end-of-day and intraday trailing drawdown?

Both floors start at the starting balance minus the drawdown limit and never come down. End-of-day trailing moves the floor only at a session close, to the highest close minus the limit: a $50,000 account with a $2,000 limit that closes a session at $50,500.00 has its floor at $48,500.00 from then on. Intraday trailing moves it during the session, to the highest balance including open gains minus the limit.

Do open gains move a trailing drawdown?

Under intraday trailing, yes. A trade that is up $500 while open lifts the floor from $48,000.00 to $48,500.00 at that moment, and if it then closes at −$250 the balance is $49,750.00 with $1,250.00 of room, not $2,000. End-of-day trailing reads only the session close, and a static floor never moves.

Does the simulator predict whether an account survives?

No. It replays only the results you type, in the order you type them, or one reshuffled order of exactly those results. It is arithmetic on your inputs, not a forecast, and it computes no odds.