Prop Firm Drawdown Rules

The two limits in plain terms

A daily loss limit says how much the account may fall inside one day. A total loss limit says how far it may fall overall. Both are shown as a percent of the account size. On a made-up $10,000 account with a 5 percent daily limit and a 10 percent total limit, the daily limit is $500 and the total limit is $1,000.

These are not the same as a broker stop out or a margin call. Those protect the lender. A challenge limit protects the firm, and it is a rule you agreed to. Breaking it is a fail, not a loss of the whole account, but the effect on a trader is similar: the attempt is over.

Static or trailing

With a static limit the floor never moves. On the made-up account it sits at $9,000 from the first day. With a trailing limit the floor follows the highest balance reached, minus the limit. The balance reached $10,700 on day 7, so the floor rose to $9,700 and stayed there. Some firms trail only until the balance reaches the starting level plus the limit, and some trail on closed balance and some on equity. The rule varies, so the arithmetic below shows the idea, not any firm's terms.

In the picture the same ten days of trading never touch the static floor. The balance ends at $9,650, which is $650 above it. But the trailing floor is $9,700, so the same path is $50 below it and the attempt ended on day 10. Nothing about the trading changed. Only the rule did.

How the daily limit is measured

The word "daily" hides two choices. First, what the limit is a percent of: the starting balance of the whole challenge, or the balance at the start of that day. Second, whether open trades count. On the made-up account, suppose the day starts at $10,400. A 5 percent limit measured on the challenge start is $500, so the day's floor is $9,900. Measured on the day's starting balance it is $520, so the floor is $9,880.

The gap is $20 on one day, small here and larger on a bigger balance. Whether a floating loss counts matters more for a bot that holds trades open. A grid or averaging bot can sit on a large unrealised loss that has not been closed yet. If open losses count, the limit can be hit by a position that might have come back.

Why this matters for a bot

• A martingale ladder. Each step doubles the size. One more step can turn a small daily loss into a breach of both limits at once. The martingale calculator shows the loss at each step.
• A grid held through a trend. The unrealised loss grows with every filled grid, and it counts if the rule uses equity.
• Many small trades. Fees and spread are paid on each one. A bot with a thin edge can drift toward the daily limit on costs alone.
• No stop of its own. A bot has no sense of the daily limit unless you build one in. The sensible fix is a hard stop inside the bot set below the firm's limit, so the bot stops before the firm does.

How to check a setup against the limits

Take the worst loss the bot can book in one day, in money, from its stop sizes and its largest open position. Compare it with the daily limit. Then take the worst drawdown in a backtest and compare it with the total limit, with a trailing floor if that is the rule. A backtest drawdown is a sample from the past, so the real worst case is larger. The prop firm challenge simulator shows how often each limit ends an attempt at a chosen risk per trade, and the guide on drawdown explains depth and recovery. To size each trade against a stop, use the position size calculator.

What this page does not tell you

It does not give the rules of any firm. Rules change, differ between account types and may be worded in ways that matter, so read yours in full before you start. Staying inside the limits does not mean the strategy has an edge, and it does not mean the account will pass.