Runway equals your cash balance divided by your net monthly burn — money out minus money in, taken from your last three actual months — and it is the single number that should decide your calendar. Founders get it wrong in two directions: they compute it off budget instead of actuals (optimistic by construction), or they treat it as a passive reading rather than a control. Runway is a control. At 18 months you choose your investors; at 9 you take the best offer; below 6 you are cutting or selling, and everyone across the table knows it. The discipline is recomputing the number monthly and letting it — not mood — trigger the decisions.
This is an operations guide on arithmetic and timing, not financial advice; financing decisions deserve professional review.
How do you compute net burn correctly?
Net burn is the decrease in your bank balance month over month: total cash out minus collected revenue, not invoiced revenue. Use the average of your last three months to smooth one-off events — an annual insurance payment, a lumpy enterprise check. Exclude the cash from the round you just raised in the burn figure itself (it sits in the balance, not the outflow), and watch for the two balance flatterers: deferred revenue you've collected but not delivered (it's a liability, and it will inflate apparent runway if you forget delivery costs) and unpaid payroll taxes that accrue invisibly until quarterly. Reconciliation against the bank statement, not the accounting system's accrual view, is the honest method.
What runway thresholds should trigger what?
The thresholds below are the practical convention most operators and investors work with — a planning frame, not a law.
| Runway | Posture | Concrete moves |
|---|---|---|
| 18+ months | Optional raising | Improve metrics, choose investors deliberately, price experiments |
| 12–18 months | Raising window open | Start the process at 15+ months so the round closes above 12 |
| 9–12 months | Urgency | Parallel-track raising and cutting plans; extend via bridge or revenue |
| Under 6 months | Survival | Cut burn to profitability of core, or transact — options narrow weekly |
Fundraising itself takes two to four months in typical markets, and that lag is the reason the process starts at fifteen months, not twelve. Per Crunchbase News' full-year tally, U.S. startups raised $328 billion in 2025 — a strong market — yet rounds still took months, and the strongest year on record for totals did not make timing risk disappear.
How do you extend runway without a round?
Three levers, in order of speed. Cut variable spend: paused experiments, renegotiated software contracts, marketing trimmed to the two channels that pay back inside a quarter — visible within one month's numbers. Slow hiring: every unfilled role is instant runway; re-time the roadmap around the team you have rather than the team you imagined. Restructure fixed costs: office, contractors, service tiers — slower, needs negotiation, but compounds. The lever founders resist is the fourth: raise prices. A 10% price increase that holds volume is often worth more than a seed extension, and unlike a cut, it strengthens the story you tell in the next round.
How does hiring interact with runway?
Every hire converts a lump of runway into a bet on faster progress, so hire against runway explicitly: at 18 months, a hire that pays back in 6–9 months is affordable; at 10 months, only hires that directly unblock revenue or the fundraise itself clear the bar. Load factors matter here — a salary is roughly 1.2–1.35× its number in true monthly cost, per employer cost data from the U.S. Bureau of Labor Statistics. The rule that keeps companies alive: no hire without naming the metric it moves and the month it should move it, and no hire that drops runway below the raising threshold at your current plan.
What signals say the runway math is lying to you?
- Burn "temporarily" spikes two months running — the spike is the new baseline.
- Revenue recognized on signed contracts while collections lag 60+ days.
- The model assumes a hire lands in month one and it lands in month four.
- Runway recomputed quarterly instead of monthly, right as the growth plan accelerates spend.
Any two of these together mean your true runway is 15–25% shorter than the headline. Discount accordingly, and tell the board the discounted number — the correction is cheaper from you than from them.
FAQ
Recompute monthly from actuals, discount for the flatterers, and start raising at fifteen months. The number doesn't negotiate — that's exactly why it's useful. Then stop reading it hopefully and start reading it literally.
For more context, read How to Build a Startup Financial Model That Survives Contact With Investors.
For more context, read startup pivot signs.
For more context, read hire first startup engineers.