Consistency Rule Calculator

This consistency rule calculator checks whether your best trading day stays within the share of total profit that your firm allows.

Inputs

Example values

Daily P&L, one value per day (no days yet) Separate days with commas or new lines. Use a dot for decimals.

Rule type

The best day may be at most this share of total profit.

Best day may be at most (% of total)

Total profit counts

Losing days reduce the total. Pick the basis your rulebook uses.

Download Excel template (.xlsx)

Daily log with formulas that starts empty: one day per row, verdict and extra profit needed at the top. A second sheet holds a hypothetical example.

Result

Live result

Best day share of total profit –

Waiting for input Add daily results and your firm’s limit.

Total profit–
Best day–
Score (total − best) / total–
Extra profit needed–

Days read: –
Winning days: –
Total profit needed to hold the rule: –
Largest profit you can add today: –

Your days

Bars show each day; a long list shows its most recent days. The best day is green. A dashed line marks the largest single day the limit allows at your current total, when it falls inside the chart.

What it means:

Enter your daily results to see a plain-language summary.

key_takeaways

Key takeaways

A consistency rule compares your single best day with your total profit.
Best day divided by the percentage gives the total profit you need.
Under a net basis a losing day shrinks the total and pushes the best day share up.

Paste your daily results, enter your firm’s limit, and see the share, the pass or fail, and how much more profit you need.

How to use this prop firm consistency calculator

Enter your daily results. One number per day, separated by commas, spaces or new lines. Use a dot for decimals and a minus sign for a losing day.
Pick the rule type. The calculator covers two ways of writing the rule: a cap on the best day or a minimum score.
Enter your firm’s limit. The example value is made up. The calculator does not know any firm’s number, so type the one from your rulebook.
Choose how losing days count. Net means losses reduce the total. Winning days only ignores them. Your rulebook decides which one applies.

The result updates as you type. Your numbers stay in your browser.

Consistency rule formula

The two versions this calculator covers compare your single best day with your total profit. The calculation is the same at any percentage. Only your firm’s number changes.

Share = best day / total profit. The rule holds while the best day stays left of the limit marker.

share        = best day / total profit
cap rule     = pass if share ≤ X%
score rule   = pass if (total − best) / total ≥ Y%     (Y = 100 − X)
total needed = best day / (X / 100)
extra needed = max(0, total needed − total)
largest day today = (X / 100) × total / (1 − X / 100)

The last line comes from adding one more winning day. If that day becomes the new best day, the rule holds while it is at most X% of the new total, which gives the formula above. A smaller day than your current best only helps, because it raises the total and leaves the best day unchanged. If the formula gives less than your current best day, no single day can bring the share back inside the limit, and the calculator shows “none”.

Worked example

Hypothetical example

Five days with results of 300, 100, −50, 80 and 70, and a limit of 30% for the best day. The figures are made up to show the arithmetic and say nothing about any firm.

Step	Net of losing days	Winning days only
Total profit	500	550
Best day	300	300
Best day share	60.00%	54.55%
Result at a 30% limit	Over the limit	Over the limit
Total needed (300 / 0.30)	1,000	1,000
Extra profit needed	500	450

To hold the rule the best day must be at most 30% of the total, so a best day of 300 needs a total of 1,000. The extra profit has to come from days that stay at or below 300. If not, a new best day moves the target again. Here that means at least two more winning days, for example two of 300, or more smaller ones.

Largest profit you can add today, net basis: 0.30 × 500 / 0.70 = 214.29. That is below the current best of 300, so no single day brings this example back inside the limit. It takes several days.

The example the calculator opens with works the other way: seven days of 120, −40, 80, 140, −60, 90 and 110 with a 35% cap. Total 440, best day 140, share 31.82%, inside the cap. The largest profit you could still add in one day is 0.35 × 440 / 0.65 = 236.92.

How does a 25% best day cap work?

At a 25% cap, a total profit of 1,000 allows a best day of up to 250. If your best day is 300, you need a total of 1,200. At 15%, a total of 2,000 allows up to 300 in one day. At 40%, a best day of 300 needs a total of 750.

The arithmetic is the same each time: best day divided by the percentage gives the total you need.

Two ways to write the rule

Best day cap. The best day may be at most a set percentage of total profit.

Score minimum. The score is total profit minus the best day, divided by total profit, and it must reach a minimum. The same trades give the same verdict: a score minimum is the same rule as a best day cap at the remaining share, because the two percentages always add up to the whole. The calculator shows both numbers for every input, so you can read your firm’s version either way.

Do losing days count?

A rule can define the total profit in two ways, and the wording is easy to misread. Under a net basis the total is the sum of all days, so a loss shrinks the denominator and pushes the best day share up. Under a winning-days-only basis the total is the sum of the profitable days and losses are ignored. The same days can pass under one and fail under the other. Use the switch that matches your rulebook, and ask the firm if the text is unclear.

What is a percentage consistency rule?

In most designs, no single day may produce more than a set share of the profit you have made. The idea is to separate steady results from one lucky day. The percentage is set by the firm that writes the rule, and a rule can apply to a challenge phase or to payouts, so read where yours applies. The worked example shows the arithmetic for other percentages. For background on why such gates exist, see Prop Firm Rules, Decoded.

How traders keep one day from dominating

Size trades the same way every day. A fixed risk per trade makes oversized winners less likely. A position size calculator does that part.
Decide what a good day is before you start. A daily target you stop at keeps a single session from carrying the whole total.
Do not chase after a large win. Extra risk after a strong day can give the gain back and push you toward a loss limit.
Log every day. A simple journal shows how your profits are spread over time. See the trading journal guide.

None of this guarantees a result. It describes habits that keep the distribution of profits flatter.

Limits of this calculator

The calculator uses a simple model. It reads the numbers you enter and applies one of two formulas. It does not know your firm’s exact wording, whether the rule uses closed or open results, how days are cut off in time, whether the check runs on the whole account or on a single payout period, or whether several trading accounts are combined. In some designs the best day is compared with a different figure; this calculator does not cover those. Percentages are rounded for display only; at the edge of the limit the share shows more decimals. The extra profit figure assumes the added days stay at or below your current best day. Results are estimates. Your firm’s rulebook decides. See also why prop firms use evaluations.

Consistency rule calculator FAQ

What is a consistency rule in prop trading?

It is a rule that limits how much of your total profit can come from one day. In most designs the best day may be at most a set percentage of the total, or the share of profit outside the best day must reach a minimum. The percentage is set by each firm.

What is the formula for consistency?

Divide your best day by your total profit. The result is the best day share. A cap rule passes when that share is at or below the limit. A score rule uses one minus that share, which is total minus best day, divided by total, and passes when it is at or above the minimum.

Do losing days count in the total?

It depends on the rule. Under a net basis, losing days reduce the total, which raises the best day share. Under a winning-days-only basis, losing days are ignored. The calculator has a switch for both. Check your rulebook for the one that applies.

Why can the same trades pass at one firm and fail at another?

The limit can differ, the rule can be a cap or a score minimum, and the total can be net or winning days only. Any one of these changes the result. Use the settings that match your own rulebook.

How much more profit do I need to fix a failed check?

Divide your best day by the limit to get the total you need, then subtract your current total. The calculator shows both. The extra profit has to come from days at or below your current best day, otherwise a new best day moves the target.

What does the largest profit you can add today mean?

It is the biggest single winning day you could still add and keep the rule intact. A day larger than that would become the new best day and push its own share above the limit.

Does this calculator know my firm’s rules?

No. The example uses made-up numbers, the limit included. Enter your firm’s limit and choose the settings your rulebook describes. The result is an estimate, and your firm’s rules decide.