Burn rate calculator: how long your cash lasts and when it runs out
Burn rate is how fast a company spends its cash. This burn rate calculator works out gross burn (everything you spend in a month), net burn (spending minus the cash that comes in) and your runway — the number of months until the bank balance reaches zero — with the actual date it happens.
Founders, finance leads and investors use it before a fundraise, a hiring decision or a board meeting. You can enter monthly totals or simply two bank balances a few months apart. Then use the what-if sliders to test revenue growth, new hires, cost cuts and new funding, see the month-by-month projection, and find out whether the company is default alive — on course to reach profitability before the money runs out.
How to use the Burn Rate Calculator
- Choose From monthly totals and enter cash in the bank, cash in each month and cash out each month — or choose From two bank balances and enter an earlier balance, today’s balance and the months between.
- Check the As of date: the zero-cash date is counted from it.
- Read gross burn, net burn, runway and the date cash runs out.
- Move the sliders for monthly revenue growth, spending cuts and new hires, and add any funding you expect.
- Read the default-alive verdict, the growth rate you would need, the charts and the projection table; download it as CSV.
Burn Rate Calculator features
Gross and net burn
Both measures side by side, from monthly figures or from two bank balances.
Runway and zero-cash date
Months of runway at today’s net burn and the calendar date the balance reaches zero.
What-if plan
Revenue growth, hiring with a start month, cost cuts and a funding round in a chosen month.
Default alive or dead
Whether cash in overtakes cash out before cash runs out, and the monthly growth that would make it so.
Charts and CSV
Cash balance and cash in against cash out, plus a projection table you can download.
Burn rate and runway formulas
Gross burn = total cash spent in a month. Net burn = cash spent − cash received (the definitions used by Carta’s burn-rate guide, July 2025, and a16z’s “16 Startup Metrics”, August 2015). Runway = cash in the bank ÷ net burn. When you only have bank statements, net burn = (earlier balance − current balance) ÷ months between them; add the revenue received over those months, divided by the months, to get gross burn.
Worked example. A start-up has 1,200,000 in the bank, collects 50,000 a month and spends 150,000. Gross burn is 150,000, net burn 100,000 and runway 12.0 months — from 14 October 2026, cash runs out around 14 October 2027. The same answer comes from balances: 1,500,000 three months ago, 1,200,000 today and 150,000 received in between.
What-if planning and default alive
Paul Graham’s 2015 essay “Default Alive or Default Dead?” asks: assuming expenses stay as they are and revenue keeps growing at its recent rate, does the company reach profitability on the money it has left? This calculator answers that with your plan, month by month, for up to ten years.
Take the example and add 5% monthly revenue growth and two hires costing 8,000 a month each from month 4. Spending rises to 166,000, revenue only catches up in month 25, but the cash runs out after 13.3 months (around 23 November 2027): default dead. The calculator finds that 6.6% monthly growth would be enough, and that 500,000 of new funding in month 6 also turns the plan default alive.
| Example plan | Runway | Verdict |
|---|---|---|
| No growth, no hires | 12.0 months | Default dead |
| 5% growth, two hires from month 4 | 13.3 months | Default dead |
| 5% growth, no hires | 17.2 months | Default dead |
| 5% growth, two hires, 500,000 raised in month 6 | Never runs out | Default alive |
Getting the inputs right
- Use cash, not accounting profit: customer payments received, and payments actually made, including loan repayments, GST or VAT and taxes.
- Average over the last three months rather than one, so a single annual bill or a late customer does not distort burn.
- Count new hires at their full cost — salary plus payroll taxes, benefits and equipment, not salary alone.
- Fundraising usually takes months, so start the next round while plenty of runway remains, not when the projection turns red.
- For a detailed month-by-month budget with one-off payments, use the cash flow calculator; for when sales cover fixed costs, the break-even calculator; for margins once revenue grows, the net margin calculator.
Burn Rate Calculator FAQ
How do you calculate burn rate?
Gross burn rate is the cash you spend in a month. Net burn rate is cash spent minus cash received. A burn rate calculator divides your cash balance by net burn to give months of runway.
What is the difference between gross burn and net burn?
Gross burn ignores revenue and shows the full monthly spend; net burn subtracts the cash customers pay. Net burn decides runway; gross burn shows how big the cost base is.
What happens when net burn is zero or negative?
Then the balance is steady or growing, so runway has no end. The calculator shows “No end” or “Cash-flow positive” instead of a number of months.
What does default alive mean?
A company is default alive if, with expenses as planned and revenue growing at its current rate, it becomes profitable before the cash runs out. Otherwise it is default dead and needs to grow faster, spend less or raise money.
Can I see runway without any growth assumptions?
Yes. The big number is always cash ÷ today’s net burn. Set growth, cuts, hires and funding to zero and the projection gives the same runway; change them to see how the plan moves the zero-cash date.
Are my numbers stored or sent anywhere?
No. Everything is calculated in your browser and nothing you type is uploaded. Results are planning estimates, not financial advice.