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Burn Rate & Runway Calculator

Runway on both a flat burn and one allowing for growth, with the date to start raising. A company growing revenue faster than costs has more runway than the flat figure says, and one hiring ahead of revenue has considerably less.

Also called: startup runway calculator, how many months of cash.

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Runway (months)
12.5

12.5 months at the current net burn of $4,000,000.00 a month. Enter growth rates to see whether you reach break even before zero. A flat burn is the one thing that never happens. A raise takes about 6 months, so start within 6.5 months to avoid negotiating against a deadline everyone can see.

Net monthly burn
$4,000,000.00
Gross monthly burn
$6,000,000.00
Runway at a flat burn
12.5
Runway allowing for growth
13
Months to break even
0
Cash left at break even
$0.00
Start raising within
6.5
Revenue as a share of costs
33.33%
On growth
Enter growth rates to see whether you reach break even before zero. A flat burn is the one thing that never happens.
On timing a raise
A raise takes about 6 months, so start within 6.5 months to avoid negotiating against a deadline everyone can see.
How this is calculated
Method and background

How this is calculated

Net burn is costs less revenue, and runway is cash divided by it. The flat calculation assumes both stay still, which they do not: modelling the growth rates separately shows whether you reach break even before you reach zero. The figure that matters operationally is not the month count but the date to start raising, since a round takes months to close and has to begin while there is still enough runway to negotiate from.

the flat form assumes nothing changes, which is the one thing that never holds
b
Net burn

Worked examples

Each of these is asserted on every build. If a change to the engine ever moved one of these answers, the build would fail before the page could print it.

a flat burn

Cash in the bank
$50,000,000.00
Monthly revenue
$2,000,000.00
Monthly costs
$6,000,000.00
Monthly revenue growth
0%
Monthly cost growth
0%
Months a raise takes
6

Runway (months)12.5

50m over a 4m net burn; the raise has to start six months earlier

Open this example

growing revenue reaches break even first

Cash in the bank
$50,000,000.00
Monthly revenue
$2,000,000.00
Monthly costs
$6,000,000.00
Monthly revenue growth
15%
Monthly cost growth
3%
Months a raise takes
6

Runway (months)12.5

boundary: revenue outgrows costs and crosses before the cash runs out

Open this example

Method and limits

What it assumes

  • Constant growth rates, which are themselves a projection.

What it deliberately does not model

  • Revenue growth is the least reliable input and the one the answer is most sensitive to.
  • A hiring plan is lumpy rather than a smooth growth rate.
  • Runway assumes no unplanned spend, and there is always unplanned spend.

Formula version 1.0.0 · definition 1.0.0 · United States · Report a problem with this calculator

Frequently asked questions

When should I start raising?
While you still have enough runway to walk away, which usually means starting six to nine months out. Raising with two months left is negotiating from a position everyone can see.
Why does the growth version differ so much?
Because burn compounds in both directions. Costs growing faster than revenue shortens runway sharply, and the reverse extends it past what a flat figure suggests.