Calculate runway

Estimate how many months current cash will last at a flat monthly burn rate, with an optional one-time change to that run rate.

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ToolRunway Calculator
Input
Output
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How it works

Monthly burn is multiplied once by one plus the entered percentage change, then cash on hand is divided by that adjusted amount. A positive 20% therefore raises 20,000 burn to 24,000, while a negative 20% reduces it to 16,000; the percentage does not compound month by month.

Formula
adjusted monthly burn = current burn × (1 + percentage change)
runway months = cash on hand ÷ adjusted monthly burn
  • The default change is 0% because an unprovided hiring plan, revenue increase, or cost reduction should not alter the current run rate.
  • The result is a constant-burn ratio rather than a month-by-month cash-flow forecast.

Worked example

100,000 in the bank, burning 20,000 a month
No assumed change to burn
Input
											Cash in bank: 100000
Monthly burn: 20000
Output
												Adjusted monthly burn: 20000
Runway months: 5
Monthly burn change percent assumed: 0

When to use this

Startup board reports, treasury reviews of a hiring plan, and cost-cutting scenarios compare unrestricted cash with a stable net monthly burn.

Edge cases

  • A -100% burn change reduces adjusted burn to zero, so finite runway is undefined and processing stops.
  • A positive 20% change raises burn from 20,000 to 24,000 instead of treating the increase as a saving.
  • A negative 20% change reduces burn once to 80% of its current value; it does not compound a further 20% reduction each month.