Startup runway calculator
Free. No signup. Know your runway in 30 seconds.
Enter your cash, burn, and revenue. See how many months you've got and the exact month you'd run out. No email required.
Looking for gross vs net burn? Use the burn rate calculator →
Your numbers
What's in the bank today.
Salaries, infra, subscriptions, everything going out.
Current recurring revenue. Leave at 0 if pre-revenue.
Month-over-month growth as a percentage. Conservative = 2–5%.
Expected monthly cost increase. 0 if expenses are flat.
At current burn and growth rate.
Runs out in about 11.7 months.
Your burn grows by 2% a month. Your revenue grows by 5% a month. At that pace, you never hit default-alive in the next 24 months.
Your cash over the next 24 months
Based on your inputs. Update them and the chart updates live.
How this calculator works
Straight division assumes next month is a copy of this one. Most startups' months aren't, so the calculator projects your balance month by month instead and reads runway off the projection. Four steps, all run in your browser:
Start from net burn
The textbook formula is runway = cash ÷ net monthly burn, where net burn is monthly expenses minus monthly revenue. That is the number this calculator starts from, before any growth.
Project 24 months forward
Revenue and expenses each compound at their own monthly rate. In month n, revenue is MRR × (1 + revenue growth)^(n − 1) and expenses are burn × (1 + expense growth)^(n − 1). Each month's cash is last month's cash plus that month's revenue minus its expenses.
Find where cash crosses zero
Runway is the point in the first month where the balance goes from positive to zero or below, interpolated inside that month: (n − 1) + cash at the start of month n ÷ cash lost during month n. The zero date is that many months from the current month, rounded up. The chart shows 24 months, but the projection keeps going (up to 120 months) so a long runway still gets a real number. Only if net cash flow is zero or positive by month 24 and cash never runs out is there no zero date.
Find the default-alive month
The first projected month in which revenue meets or exceeds expenses. If revenue already covers expenses today, you're default alive now; if it never catches up inside 24 months, the calculator says so. The question comes from Paul Graham's essay “Default Alive or Default Dead?”.
A worked example
The calculator's starting inputs: $500,000 in the bank, $50,000 of monthly expenses, $10,000 of MRR, revenue growing 5% a month, and expenses growing 2% a month. Straight division says $500,000 ÷ ($50,000 − $10,000) = 12.5 months. The projection disagrees:
| Month | Revenue | Expenses | Cash at month end |
|---|---|---|---|
| 1 | $10,000 | $50,000 | $460,000 |
| 2 | $10,500 | $51,000 | $419,500 |
| 3 | $11,025 | $52,020 | $378,505 |
| 6 | $12,763 | $55,204 | $252,613 |
| 11 | $16,289 | $60,950 | $33,632 |
| 12 | $17,103 | $62,169 | −$11,433 |
Expenses grow from a larger base, so the monthly loss widens from $40,000 to about $45,000 even though revenue grows faster in percentage terms. Cash crosses zero during month 12: $33,632 at the start against a $45,065 loss, so runway is 11 + 33,632 ÷ 45,065 = 11.7 months — almost a month shorter than the straight division. Revenue never catches expenses inside the 24-month window, so there is no default-alive month, and 11.7 months lands in the calculator's “Watch” band.
How much runway is enough?
The status bands are this calculator's own: 18 months or more is healthy, 9 to 18 is watch, 3 to 9 is raise or cut, and under 3 is a crisis. They sit close to what investors have published. Fred Wilson's rule in “How Much Money To Raise” is to “raise 12-18 months of cash each time you raise money. Less than a year is too little.” Bessemer's State of the Cloud 2023 benchmarks for SaaS founders put it as “Runway of 12 months (good), 18 months (better), 24+ months (best).” And on timing, Wilson's burn-rate primer says to raise again “at least six months before you run out of cash.” Subtract six months from your zero date and you have the last comfortable month to start.
The full method, including when straight division misleads and how to report runway to investors, is in how to calculate startup runway.
What this calculator does and doesn't do
This calculator gives you a back-of-envelope runway estimate. It's a starting point, not a financial model. It assumes:
- Steady compound growth at the rates you entered (real growth is rarely that smooth)
- No one-time expenses or income (fundraising rounds, big invoices, seasonal costs)
- No currency or tax effects
- Revenue starts collecting immediately (no payment delays)
If you want a forecast that models scenarios, handles one-time items, and feeds a repeatable monthly investor update, that's what Vectig does.
Prefer to do this in Claude or ChatGPT? I also wrote a prompt that builds a three-scenario model you can paste anywhere.
Related questions
What is a startup runway?
Runway is how many months your startup can operate before running out of cash, assuming current burn and revenue. If you have $500K and burn $50K/month with no revenue, you have 10 months of runway.
How is runway calculated?
Runway = cash ÷ (monthly burn − monthly revenue). If revenue is growing, runway extends over time; if expenses are growing faster, it shortens. This calculator models both.
What's a healthy runway for a startup?
Most investors want a round to buy 12–18 months or more: Fred Wilson's long-standing advice is to raise 12–18 months of cash each time, and Bessemer's SaaS benchmarks call 12 months of runway good, 18 better, and 24 or more best. Below 6 months, you should be raising, cutting burn, or getting profitable. Below 3 months is a crisis.
What's “default alive”?
Term coined by Paul Graham in his 2015 essay “Default Alive or Default Dead?” A startup is default-alive if, with expenses and revenue growth on their current path, it reaches profitability on the money it has left — meaning you don't strictly need to raise. This calculator estimates when (or if) revenue catches expenses in the next 24 months.
Is this calculator accurate enough to use for investor meetings?
For a rough back-of-envelope number, yes. For actual investor updates or board meetings, you want a model that accounts for one-time expenses, plus scenario modeling and a repeatable monthly process — which is what Vectig does.