Runway is your cash divided by your monthly net burn: the number of months before the bank balance reads zero. Twelve months is comfortable. Six is a deadline. Three is not a runway at all, it is a cliff with attractive lighting. Recalculate it every time burn or revenue moves, which is more often than most founders admit.
Runway (months) = cash on hand ÷ monthly net burn
Drop in your cash on hand and monthly net burn. The calculator tells you how many months until the bank account hits zero. Under three months is an emergency. Six to twelve is comfortable. Re-run it every time burn or revenue changes; founders who track this monthly outlive founders who don't.
Your numbers
Bank account balance today. Don't include money you haven't received yet.
Cash out minus cash in. Use the worst recent month, not the best.
The verdict
Zero around Apr 2027
Long enough to think clearly, short enough to stay honest. Spend it on conversion and retention. Investors are a poor substitute for customers and considerably harder to please.
What the number means
| Months of runway | Reading | What to do about it |
|---|---|---|
| Net burn of zero or less | Healthy | Your revenue covers your costs, so the runway is infinite and this calculator has nothing left to tell you. Economists call this a going concern. Everyone else calls it a relief. |
| Under 3 months | Act now | Raising a round takes three to six months, so you are not fundraising any more, you are closing. Anything this week that is not an investor conversation or an invoice is a hobby. |
| 3 to 6 months | Fragile | The fundraising window, and it only counts as one if the deck already exists. If it does not, cut burn this week rather than next, while cutting is still a choice. |
| 6 to 12 months | Healthy | Long enough to think clearly, short enough to stay honest. Spend it on conversion and retention. Investors are a poor substitute for customers and considerably harder to please. |
| Over 12 months | Healthy | Cash has stopped being your constraint, which means you are now the constraint. The question is no longer how long you can survive but what you are doing with the survival. |
Worked examples
| Situation | Numbers in | Answer out | Verdict |
|---|---|---|---|
| Solo founder, no revenue | Cash $30,000 · Net burn $4,000 | 7.5 months | Healthy. Enough room to find a first paying customer without the panic tax. |
| Two founders, pre-seed | Cash $120,000 · Net burn $15,000 | 8.0 months | Healthy, but only just. Start the raise at month four, not month seven. |
| Seed stage, six staff | Cash $400,000 · Net burn $95,000 | 4.2 months | Fundraising window, and closing. Either the round is already in motion or the headcount is. |
| Bootstrapped, revenue ahead of costs | Cash $18,000 · Net burn -$2,000 | Infinite | No runway to calculate. You have built the rarest thing in startups: a business. |
How this is calculated
Runway (months) = cash_on_hand / monthly_net_burn.
Net burn = total cash out − total cash in. Net, not gross. Gross burn double-counts the runway your revenue is already covering.
The "zero around …" date assumes burn stays flat. In practice burn drifts up as you hire and down as revenue grows; re-run the calc monthly with the latest bank balance.
Verdict thresholds are calibrated against the typical fundraise cycle: 3-6 months from first investor coffee to wire is normal, so under 3 months of runway means you are not raising, you are closing.
What this doesn't tell you
- Whether your burn is the right shape. $20K/month split 80% engineering / 20% distribution is different from 80% paid acquisition / 20% engineering. Two startups with the same runway can have very different odds.
- Whether you can raise. Runway tells you the deadline. Whether investors will fund you at this stage depends on traction, team, and market, none of which this calc measures.
- Whether to cut. Cutting burn extends runway but slows growth. The right move depends on whether you are pre-PMF (cut hard) or post-PMF (lean in).
How many months of runway should a startup have?
Eighteen months if you have just raised, twelve if you are steady, and never fewer than six by choice. The number comes from the fundraise cycle rather than from any law of nature: three to six months from the first investor coffee to money in the account is normal, and you want to start that conversation from a position of interest rather than desperation. Investors can smell the difference across a room.
What is the difference between runway and burn rate?
Burn rate is the speed, runway is the distance. Burn is how much cash leaves per month; runway is how many months of it your balance can absorb. The pair only makes sense together, in the same way that knowing you are driving at seventy tells you nothing useful until somebody mentions how much petrol is in the tank.
How do you extend runway without cutting the team?
Raise prices, collect faster, and stop paying annually for tools you use monthly. Price is the fastest lever because it moves net burn without touching costs, and most early products are underpriced by a margin that would embarrass their founders. Chasing overdue invoices is unglamorous and often buys a month on its own.
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Frequently asked questions
What counts as 'burn'?
Should I include money I haven't raised yet?
I'm bootstrapped with no monthly burn. Does this apply?
Why is 3 months the panic line?
Runway is the deadline.
The expensive way to run out of it is building something nobody wanted. ShipFit forces the nine decisions that make that less likely, before the clock matters.