Maximum compliant size calculator for prop accounts
The largest position that satisfies every limit at once — the firm's daily cap, its total drawdown, and your own rule. The tightest one governs, and this names which.
Max compliant size
0.83
Governed by: Your own per-trade cap
Daily loss remaining5.33
Total drawdown remaining6.17
Your own per-trade cap0.83
Satisfies every limit on planned loss. A gap through the stop can still breach all three.
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Keeps every limit current as trades close, so this number stays right.
What this covers
Three constraints at once. Add your own figures; this does not know your firm.
Sizes on planned loss only. A gap through the stop breaches limits this figure satisfies.
Excludes fees and spread — use the fee-adjusted sizer for the all-in number.
Formula and assumptions
Loss per unit = |entry − stop| × contract value.
Allowed size for each limit = that limit's remaining budget ÷ loss per unit.
Governing limit = the smallest of the three. Worst wins; nothing is averaged.
Truncated down, so the result cannot exceed any limit.
max_compliant_size.v1
Worked example
Example — check your own firm's rules.
Daily loss remaining$3,200
Total drawdown remaining$3,700
Your own per-trade cap$500
Entry → stop1.0840 → 1.0900
Loss per lot$600
Governing limitYour own cap
Max compliant size0.83 lots
Common mistakes
Sizing against the daily limit alone while total drawdown is the tighter one.
Averaging the limits instead of taking the smallest.
Treating your own rule as advisory once the firm's limits leave more room.
Forgetting that open positions already consume part of every budget here.
Limitations
This is arithmetic on numbers you supplied. It does not know your broker, your account, or the market. It does not predict price, does not say whether to take a trade, and is not advice. Maximelion is not affiliated with any broker or prop firm, and nothing here is endorsed by one.
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Last reviewed 25 July 2026