Trailing drawdown calculator
A trailing rule asks how far you are below your best moment, and the floor it sets ratchets up and never comes back down. What counts as that best moment decides accounts: under an intraday rule it is your equity peak including unrealised profit; under an end-of-day rule it is a daily balance, so a floating high does not move the floor at all. And the distance to that floor is not what you trade against — pips at your position size is.
When the floor stops trailing
A floor that climbs forever and a floor that halts at breakeven are different rules wearing one name, and which one you are under changes the arithmetic above.
Where the floor never stops, every new high raises the bar permanently: at each new high the room you are managing is the whole allowance and no more — the same room you had on day one, because the floor came up with you — and anywhere below that high it is smaller than that by exactly how far below it you have come. Where it locks at the starting balance, the ratchet runs only until the floor reaches that balance and then stops for good — and everything you make after that point is genuinely yours to lose.
The two rules produce an identical number until the trail would have carried the floor above where you began — that is, until your highest point exceeds your starting balance by more than the allowance. Before that moment the setting looks inert, which is exactly why it gets skimmed. After it, the rules diverge permanently and in one direction. If your agreement does not say plainly which one it describes, that is the question to settle before sizing anything against the distance above.
Why pips, and not the money figure
A room of 1,700 in account currency tells you nothing you can act on, because you do not trade in account currency — you trade in lots. The same 1,700 is 170 pips at one standard lot on a ten-per-pip instrument, and 17 pips at ten lots. Only the second number tells you whether the position you are holding is survivable, and it is the number that changes every time you resize.
Raw, ECN and standard accounts are not the same arithmetic
On a raw spread or ECN account the broker quotes a thin spread and charges a separate commission per lot per side. On a standard account there is no commission and the cost is folded into a wider spread. The totals can be similar; what differs is that the commission is fixed per lot while the spread widens when the market does — so the two account types behave differently in exactly the conditions that breach accounts.
Either way the round trip is a cost you pay before the market has moved at all, and it comes out of the same room the floor is measuring. At small distances to the floor it can be a meaningful share of what is left, which the panel above states directly. The full accounting is at execution cost, and the widening itself at spread widening.
What this does not do
The calculator does not know your rulebook. Your firm's terms govern — how the high-water mark is sampled, whether it locks, what counts as a trading day — and where this disagrees with your agreement, your agreement is right. Pip values, spreads and margin requirements vary by broker and by instrument, so the presets are starting points to overwrite rather than facts about your account.
It does not tell you what to trade or how large, and it computes no probability of survival. A survival figure needs an estimate of your edge, and an edge estimate supplied here would be invented rather than measured. What it gives you is a distance, in the unit you actually trade in. What you do about it stays yours.
The live version — recomputed on every fill, with correlated positions folded into one exposure — is the Prop-Evaluee Risk Guardian. If a trailing rule has already ended an evaluation, the breach can be reconstructed from your own account record: see Prop-Breach Forensics. The term is defined at trailing drawdown, and why an account can be breached while closing in profit is the mechanism this floor produces. If you are not certain which variant your agreement describes,work out which drawdown rule you have first — the calculator above assumes you already know. Where the constraint is on the size of a single day instead, that is the consistency rule calculator. The distance above is the room you have; how likely your sizing is to spend it before the evaluation ends is the risk of ruin calculator. The full list is under calculators. And when the inputs cannot support an answer, the panel above refuses and says why rather than rendering a zero — why an instrument refuses to answer is that design, written down.