Prop Firm Drawdown Calculator: Daily & Max Loss Buffer

A funded account is won or lost on one number: how much room you have left before a drawdown rule closes the account. This calculator turns your firm's percentage limits into two hard dollar figures — your daily buffer and your total (max) buffer — so you size trades against real headroom instead of guessing.

What the calculator does

You enter five values: starting balance, current equity, peak equity, your firm's daily drawdown %, and its maximum drawdown %. The tool returns two buffers, both in account currency:

• Daily buffer — how much more you can lose today before the daily limit trips.
• Total buffer — how much more you can lose overall before the account-wide limit trips.

The smaller of the two is your real ceiling for the session. When either buffer reaches zero, the rule is breached.

The formulas

The tool computes:

dailyBuffer = balance × dailyDD% − dayLoss
totalBuffer = peak × maxDD% − drawdownFromPeak

Two derived quantities feed those lines:

• dayLoss = startingBalance − currentEquity — your realised plus floating loss since the day's anchor. (If you're up on the day, dayLoss is negative and your daily buffer simply exceeds the raw allowance.)
• drawdownFromPeak = peakEquity − currentEquity — how far you've fallen from your highest equity. This matters because most firms use a trailing max drawdown that locks to your peak, not your starting balance.

The daily allowance is a percentage of the day's starting balance; the total allowance is a percentage of peak equity. Subtract what you've already given back and you have the dollars left.

Worked example

Say you have a $100,000 evaluation with a 5% daily and 10% maximum drawdown.

• Starting balance (today): $100,000
• Current equity: $99,500
• Peak equity: $103,000

First the daily side:

• dayLoss = 100,000 − 99,500 = $500
• dailyBuffer = 100,000 × 0.05 − 500 = 5,000 − 500 = $4,500

Now the total side, using the trailing peak:

• drawdownFromPeak = 103,000 − 99,500 = $3,500
• totalBuffer = 103,000 × 0.10 − 3,500 = 10,300 − 3,500 = $6,800

Your daily buffer is $4,500 and your total buffer is $6,800. The daily limit binds first, so $4,500 is the most you can lose today — and at, say, $10 per pip on one lot, that's 450 pips of room. Size your stops so a string of losers can't cross it.

Edge cases and pitfalls

• Static vs trailing max drawdown. This tool models a peak-anchored (trailing) max drawdown, which is the stricter and more common rule. If your firm freezes the max-loss line at your starting balance once you pass the initial target, enter your starting balance as the peak to mirror a static limit. Read the rulebook — the anchor changes the math.
• Equity, not balance, triggers breaches. Floating losses on open trades count. A firm that measures drawdown on equity can disqualify you intraday even though no trade has closed. Use current equity (including open P/L), not closed balance.
• The day's anchor and reset time. "Starting balance" means equity at the daily reset (often 00:00 server time), not your original deposit. Some firms anchor the daily limit to the higher of balance or equity at reset. Re-enter the figure each new day, and confirm your platform's server timezone.

FXNX is a broker, not a prop firm — but the same discipline applies to your own capital. NX Pro's raw spreads from 0.0 pips keep cost out of your buffer math when you're trading tight.