Runway

What is Runway?

Runway is the countdown clock on your startup. It tells you how many months you can keep paying salaries, servers, and rent before the bank account hits zero. The metaphor comes from aviation: a plane has a fixed length of tarmac to reach takeoff speed, and your company has a fixed amount of cash to reach revenue, profitability, or the next funding round.

Day to day, runway shapes almost every decision a founder makes. It determines whether you can afford to hire, how aggressively you can spend on marketing, and when you need to start fundraising. Investors ask about it in nearly every pitch meeting because it reveals how much time you have to prove your assumptions before you are forced to raise on bad terms or shut down.

Runway is not static. It shrinks when you hire and grows when revenue climbs or you cut costs. Treat it as a living number you recalculate every month, not something you work out once after a funding round and then forget.

How to calculate runway

The formula is simple: Runway (months) = Cash balance / Net monthly burn, where net monthly burn is your monthly expenses minus monthly revenue. Net burn is closely tied to your burn rate, so get that number right first.

Worked example: say your startup has $240,000 in the bank. You spend $32,000 per month on salaries, tools, and hosting, and you bring in $8,000 per month in revenue. Your net monthly burn is $32,000 minus $8,000, which is $24,000. Runway is $240,000 divided by $24,000, which gives you 10 months.

Use a conservative version too: assume revenue stays flat and one surprise expense shows up. If the conservative number drops below six months, it is time to act.

Why runway matters for startups

For a small team, runway is the difference between negotiating from strength and begging for a bridge round. Fundraising typically takes three to six months from first meeting to money in the bank, so a founder with four months of runway is already late. Knowing your runway tells you exactly when to start those conversations.

Runway also forces prioritization. With 18 months of cash you can run experiments; with 5 months you need to focus on the single thing most likely to produce revenue or a fundable milestone. Teams that track runway weekly make sharper calls on hiring, pricing, and scope than teams that discover their position from a low-balance alert.

Runway in practice

Imagine you run a two-person SaaS startup that just closed a $300,000 pre-seed round. Your combined burn is $20,000 per month, giving you 15 months. You decide that hiring a third engineer at $10,000 per month would cut runway to 10 months, so instead you contract out a specific feature for a one-time $15,000. Six months later, MRR reaches $12,000, net burn falls to $8,000, and your remaining $180,000 now covers more than 22 months. That single decision, made by looking at the runway math instead of gut feel, bought you the time to reach seed funding conversations with real traction.

Benchmarks and rules of thumb

Most investors advise raising enough for 18 to 24 months of runway, so you have 12 to 18 months to build and a buffer to fundraise. Many founders treat six months as the red line: below that, you either cut costs, push hard on revenue, or start raising immediately. Bootstrapped teams often run leaner, and if you are bootstrapping, runway is simply how long your savings and revenue keep you alive.

Common mistakes

• Using gross burn instead of net burn. Ignoring revenue makes runway look shorter than it is; ignoring one-time costs makes it look longer. Use net burn from real bank statements.
• Assuming revenue growth in the projection. Calculate runway with flat revenue. Growth is upside, not a plan.
• Starting to fundraise too late. Raising with three months left signals desperation and weakens your terms. Start at nine months or more.
• Forgetting lumpy expenses. Annual insurance, taxes, and contractor invoices can wipe out a month of runway overnight. Model them explicitly.

Runway sits at the center of startup finance, connecting your burn rate and cash flow to your fundraising strategy. Understanding it alongside unit economics tells you not just how long you can survive, but whether the business you are funding is worth extending.