How to use the prop firm consistency rule calculator
- Enter your daily results, oldest first, separated by spaces or new lines. Write a losing day with a minus sign, like -200. Days with no trades can be left out or entered as 0.
- Choose what counts as total profit. "All days" is the net result with losing days taken off. "Profitable days" adds up only the winning days. Firms word the rule differently, so use the one on your firm's rules page.
- Pick the limit, the most your best day may be as a share of total profit. The list offers 20%, 30%, 40% and 50%, and a custom field takes any other figure.
- Add the profit target if you want to see how it sits next to the rule. It is optional.
The hero figure is the best day's share of the total. The tiles show the verdict, the largest best day the current total allows, the extra profit needed if the rule fails and the biggest single day you can still add. The first chart draws every day with the cap on the best day as a dashed line, and the second shows the share against the limit. Your inputs are kept in the address bar, so you can copy the link and come back to the same numbers.
The consistency rule formula
The rule is one inequality: the best day may not be more than the limit times the total profit. Everything else follows from it.
best day share = best day ÷ total profit
the rule passes when best day share ≤ limit
largest best day allowed = limit × total profit
total needed = best day ÷ limit
extra profit = total needed − total profit
biggest new day = limit × total profit ÷ (1 − limit)
The best day is your largest single-day profit. Total profit is the sum of your days, on the basis you chose. The limit is written as a fraction here, so 40% is 0.40. The extra profit is what you still have to earn, on days no bigger than your best, for the best day to fit under the limit. The biggest new day comes from solving limit × (total + x) ≥ x for x: a new day of that size becomes the best day and lands exactly on the limit, and anything larger breaks the rule.
Worked example
Seven days of results: 450, 300, 800, −200, 600, 350 and 500. The limit is 40% of the total profit, counting all days.
The best day makes up a little over a quarter of the profit, comfortably inside the rule, and the dashed line at $1,120 sits well above the $800 column. Those are the figures the calculator opens with. A new day of $1,867 would raise the total to $4,667 and be exactly 40% of it, while $2,000 would raise the total to $4,800 and be 41.7%, which fails.
When the rule fails: how much more profit you need
Keep the same seven days and lower the limit to 25%. The share is still 28.6%, which is now over the limit, so the rule fails. The total has to reach $800 ÷ 25% = $3,200, which is $400 more than the $2,800 you have. At an average of $400 a day that is about one more day, as long as that day is no bigger than the $800 best day.
This is the useful direction of the maths. You cannot shrink the best day, but you can grow the total. Profit earned on ordinary days lifts the total and leaves the best day where it is, so the share falls until it is under the limit. Notice that a failing rule is a statement about the gap between your best day and your other days. A large winner is not the problem. The problem is a total that has not caught up with it.
All days or profitable days only?
Firms define total profit in two ways, and the choice moves the share.
- All days (net). Total profit is the sum of every day, so a losing day reduces it. On the example that is $2,800 and the share is 28.6%.
- Profitable days only. Total profit is the sum of the winning days, so losses are ignored. On the example that is $3,000 (the same days without the −$200) and the share is 26.7%.
A losing day makes the rule harder on the first basis and has no effect on the second. Read the wording on the rules page: "net profit" points to all days, and "sum of profitable days" points to the second basis. Examples on the page settle it. Enter the same results both ways if you are not sure, and plan around the stricter answer until you have confirmed it. If your firm calls it something else, such as a best-day rule, the arithmetic is the same once you know which total it uses.
What a limit means for how many days you need
A limit puts a floor under the number of days you need. If every day earned the same amount, each day would be 1 ÷ the number of days of the total, so the rule needs at least 1 ÷ limit days.
Real days are never equal, so the practical number is higher. The calculator shows the effect directly: add a large day and watch the share climb. Read more on the idea in the consistency glossary entry.
Planning around the rule
The cap is a planning number. With a total of $2,800 and a 40% limit, no single day should exceed $1,120 for the rule to hold today, and since a big day also grows the total, the practical ceiling for the next day is the "biggest day you can add" figure. After a large winner the total has not yet grown to match it, which is the moment the share is highest. Some traders choose to cut size or stop for the day after a large win, which is also what a good trading plan often asks for.
If you also have a profit target, the higher of the two requirements sets the total you must reach. With days of 100 and 900, a 40% limit and a target of 1,500, the best day needs a total of 900 ÷ 40% = 2,250, which is above the target, so 2,250 is the number to aim for. The prop firm payout calculator shows what a payout is worth once you get there, and the prop firm drawdown calculator shows the loss limits you are trading inside while you do.
Common prop firm consistency rule mistakes
- Using the wrong percentage. Limits differ between firms and between stages of the same programme. Read your own rules page, not a forum post.
- Mixing the two definitions of total profit. Net of losing days and profitable days only give different shares for the same results.
- Forgetting that the rule looks at the whole period. One large day stays in the calculation for as long as the rule covers it.
- Misjudging what counts as a day. Firms use their own time zone and cut-off, so two trades you think belong to one day may fall on two.
- Chasing the fix with bigger trades. Raising size to catch up can create a new oversized day. Earn the extra profit on ordinary days.
- Checking only at payout time. Run the numbers every few days. Waiting until the request is made leaves no room to fix the share, and a journal that records each day makes the check routine (see the prop firm trading journal guide).
What the calculator does not know
It does not know your firm (see what a prop firm is for how these programmes work). Whether the rule applies during the evaluation, on the funded account or only at payout, what counts as a day, whether open trades are included and what happens when the share is over the limit are all set by the firm and can change. It treats the results you enter as final and in one currency. It does not know about other rules your firm may have, such as separate limits on loss or on the minimum number of trading days. Use it to plan, and treat your firm's own dashboard and rules page as the authority. Nothing here is investment advice.
Frequently asked questions
What is a consistency rule in prop trading?
A consistency rule limits how much of your total profit a single day can account for. If the limit is 40% and your total profit is $2,000, your best day may be at most $800. The aim is to reward repeatable trading rather than one lucky day.
How do I calculate the consistency rule?
Divide your best day by your total profit and compare the result with the limit. With a best day of $800 and a total of $2,800 the share is 28.6%, which is under a 40% limit. The calculator does this for any list of daily results.
What does a 30% consistency rule mean?
It means the best day may be at most 30% of the total profit. That needs at least four days of similar size, because three equal days would each be 33%. In practice you need more days than that, since real days differ in size.
What does a 40% consistency rule mean?
Your best day may be at most 40% of the total profit, which needs at least three days of similar size. A total of $2,500 allows a best day of $1,000, and a total of $2,800 allows $1,120.
Is total profit all days or only profitable days?
It depends on the firm. Some count the net result of every day, so a losing day lowers the total, and others add up only the winning days. The calculator has a switch for both, and the two can give different shares for the same results.
How much more profit do I need to pass the consistency rule?
Divide your best day by the limit to get the total you need, then subtract the total you have. With a best day of $800 and a 25% limit you need $3,200, which is $400 more than a total of $2,800. The extra profit has to come on days no bigger than your best day.
What is the biggest day I can add without breaking the rule?
It is the limit times the total, divided by one minus the limit. With a 40% limit and a total of $2,800 that is $1,867. A new day of exactly that size lands on the limit, and a larger one breaks it.
Can I remove my best day from the calculation?
No, not in this calculator: it counts every day you enter. Whether a day can be excluded is set by your firm's rules page, so do not assume it can.
What happens if I fail the consistency rule?
That is the firm's decision, not the calculator's, and the rules page says what the consequence is. The usual way back under the limit is to grow the total profit on ordinary days, and the calculator shows how much more it takes.
Does the consistency rule apply to the profit target?
The two are separate requirements, and you generally need both. If the rule needs a higher total than the target, the rule sets the number you aim for. Enter your target in the calculator to see which of the two is the higher bar.