Cash Runway Calculator
How long does your cash last? Default alive or default dead? With burn multiple and a month-by-month projection, not a single number.
Per Paul Graham (2015), "Default Alive or Default Dead?" — a company is default alive if, at its current growth rate, revenue will exceed burn before cash runs out.
View the TypeScript implementation on GitHub: packages/calc/src/cash-runway.ts · view tests
What this means
Runway is a time budget. It tells you how long you have to execute before you either turn the business profitable or go back for more capital. The most useful number is rarely the flat runway — it's the distance between today and your next fundraising milestone, and whether you can hit that milestone with the time you have.
Byron Malone, founder of Bedrocka Tools and 15-year operator advisor: “Default alive isn’t a victory condition; it’s the starting line. Your job is to protect that status while accelerating growth, not relax once you’ve crossed it.” The market can turn and a 10% growth rate can become a 2% growth rate fast, flipping you into default dead without any single decision causing it. If you’re default dead, you have two levers: raise or cut. The worst outcome is doing neither and watching the runway tick down until it dictates the answer for you.
One pattern I’ve seen again and again advising early-stage operators: the runway figure that predicts survival isn’t the headline month count — it’s the slope of net burn. Two companies can show the same nine months of cash, and the one whose monthly burn is shrinking reaches default-alive while the one whose burn is climbing stalls. Track the trend line, not just the balance.
Worked example
$500K cash, $75K burn, $40K monthly revenue growing 8% month-over-month. Flat net burn = $35K/month, so flat runway is about 14.3 months. With growth, revenue crosses burn around month 9 and you become profitable before running out of cash — default alive. Burn multiple = ($75K − $40K) ÷ ($40K × 8%) = 10.9×, which is concerning despite the default-alive status — you're burning a lot to generate each marginal revenue dollar, and if growth dips below 6% you flip to default dead. The classification is binary; the burn multiple tells you how comfortable that classification is.
Frequently asked questions
The information and tools on this website are for general educational purposes only and do not constitute financial, investment, legal, or tax advice. Consult a licensed professional for decisions specific to your situation.