# Burn rate calculator

> Free burn rate calculator: enter your cash at the start and end of a period to get net burn per month, gross burn, and the runway left. No sign-up.

Canonical page: https://superbooks.io/tools/burn-rate-calculator/

Burn rate is how much cash a business loses each month. Net burn is the fall in your cash balance divided by the months it took; gross burn is everything you spent, divided the same way.

Formula: Net burn = (cash at start − cash at end) ÷ months. Gross burn = total spending ÷ months. Runway = cash at end ÷ net burn.

GET https://app.superbooks.io/api/tools/burn-rate

## Questions

### What is the difference between net burn and gross burn?

Gross burn is everything the business spends in a month. Net burn is what is left after revenue comes in: spending minus revenue, which is the same as the fall in your cash balance. Runway is worked out from net burn.

### Over how many months should I measure burn?

Long enough to smooth out one-off bills, short enough to reflect how you spend now. Three months is common; the SuperBooks runway report uses the median of the last three full months.

### What does a negative burn rate mean?

Your cash went up over the period: the business brought in more than it spent, so it is not burning cash and there is no runway limit at that pace.