How long until the money runs out?

Runway is the simplest survival number there is: cash in the bank divided by what you burn each month. But revenue rarely stands still — grow it fast enough and you break even before the cash runs dry. That's the line between default alive and default deadPaul Graham's terms: a startup is default alive if its current growth carries it to profitability before the money runs out, and default dead if it doesn't — without raising more or changing course..

We havein the bank, spenda month,
bring ina month, growing% a monthMonth-over-month revenue growth. At 0% revenue is flat and runway is just cash ÷ net burn; turn it up and rising revenue shrinks the burn until it flips to a surplus..
6.3months of runway

€500 000 ÷ €80 000 net burn a month.

€80knet burn / mo
6.3runway (months)
runs dry
Default deadAt a flat €80 000 net burn a month, €500 000 lasts about 6.3 months. With no revenue growth there's no path off the clock — extend the cash or grow revenue.
runs dry · 6.3 mo€500k
now2 mo4 mo6 mo

The balance slides toward zero — where it hits the line is the day the money's gone. Rising revenue bends the slope flatter, but here it doesn't bend in time.

Revenue growth / moRunway
0%now
6.3 modead
3%
6.4 modead
6%
6.5 modead
10%
6.8 modead
15%
7.4 modead
25%
alive · profit in 7.2 mo

Same cash, same spending — only the monthly revenue growth changes. Watch for the threshold where the runway flips from a finite countdown to : that's the growth rate that turns default dead into default alive. Click a rate to load it above.

runway = cash ÷ net burn · “default alive” after Paul Graham