Startup Runway Calculator
Enter your cash, monthly expenses, revenue and growth rates to project your cash balance month by month, find your runway, zero-cash date and break-even month, and see whether you are default alive. Nothing leaves your browser.
Month-by-month projection
A planning estimate that assumes steady monthly growth rates. Real revenue and costs are lumpy, so keep a safety margin and re-run it every month with actual numbers.
How to use the Startup Runway Calculator
- Enter your cash in the bank today and your total monthly expenses (gross burn).
- Add revenue: your current monthly revenue and the monthly growth rate you expect.
- Set expense growth to reflect planned hiring or rising costs (0% keeps expenses flat).
- Model a raise (optional): the amount of new funding and the month it lands.
- Read the results: runway, zero-cash date, break-even month and the default alive/dead verdict, then explore the chart and table or download the CSV.
Runway and burn rate formulas
- Gross burn = total cash spent per month
- Net burn = gross burn − monthly cash revenue
- Simple runway (months) = cash in the bank ÷ net burn
- Revenue in month n = current revenue × (1 + revenue growth)n−1
- Expenses in month n = current expenses × (1 + expense growth)n−1
- Cash at month end = previous cash + funding + revenue − expenses
The projected runway is the point where the cash balance hits zero. Inside the month where it turns negative, the calculator interpolates: months already completed + cash left at the start of that month ÷ that month's net burn. The zero-cash date is that many months after the 1st of your starting month.
Worked example
A startup has $750,000 in the bank, spends $85,000 a month and earns $25,000 a month in revenue. Net burn is $60,000, so the simple runway is 12.5 months. With 8% monthly revenue growth and 2% monthly expense growth, the gap narrows every month:
| Month | Revenue | Expenses | Net burn |
|---|---|---|---|
| 1 | $25,000 | $85,000 | $60,000 |
| 6 | $36,733 | $93,847 | $57,114 |
| 12 | $58,291 | $105,687 | $47,396 |
| 14 | $67,991 | $109,957 | $41,966 |
Even so, the cash runs out during month 14 (a runway of about 13.9 months), while revenue only overtakes expenses in month 23. This company is default dead: it needs roughly $184,000 more, or lower costs or faster growth, to reach break-even. These are the default numbers loaded in the calculator above.
Ways to extend your runway
- Cut the biggest lines first. Payroll is usually 60–80% of startup burn; a hiring freeze moves runway more than trimming software.
- Collect cash earlier. Annual prepaid plans bring a year of revenue in up front; see the profit margin calculator to check discounts still pay off.
- Raise before you need to. Start fundraising with at least 6–9 months of runway left.
- Re-forecast monthly with actual numbers and watch growth with the percentage change calculator.
Frequently asked questions
How do you calculate startup runway?
Simple runway = cash in the bank ÷ net monthly burn, where net burn = monthly expenses − monthly revenue. For example $600,000 of cash with $80,000 of expenses and $30,000 of revenue gives a net burn of $50,000 and 12 months of runway. This calculator also applies monthly growth rates to revenue and expenses and finds the exact month the cash balance reaches zero.
What is the difference between gross burn and net burn?
Gross burn is everything you spend in a month: salaries, rent, software, marketing. Net burn is gross burn minus the cash revenue that comes in. Runway is based on net burn, because revenue offsets part of what you spend.
What does default alive or default dead mean?
The terms were coined by Paul Graham. A startup is default alive if, assuming current expenses stay on plan and revenue keeps growing at the recent rate, it reaches profitability before running out of money. If it runs out of cash first, it is default dead and needs to raise money, cut costs or grow faster.
How much runway should a startup have?
Many investors and founders aim for 18 to 24 months of runway after a fundraise, and to start the next raise with at least 6 to 9 months left, because fundraising often takes 3 to 6 months. Less than 6 months is usually treated as an emergency.
What monthly growth rate should I use?
Use your actual recent average, for example the compound monthly growth of revenue over the last 3 to 6 months. A rate of 5% per month is about 80% per year and 10% per month is about 214% per year. Being conservative gives you a safer plan.
Does the calculator account for funding I expect to raise?
Yes. Enter the amount and the month number it should arrive in. Only include funding you are confident about; it is wise to check the plan without it too.