Runway Calculator
Gross and net burn, how many months your cash lasts and the date it runs out, with optional monthly growth in revenue and costs simulated month by month, and the burn multiple.
Result…
How it's calculated
Gross burn = expenses a month Net burn = expenses − revenue Runway = cash ÷ net burn (flat figures) With growth: month n expenses = E × (1 + gₑ)^(n − 1), revenue = R × (1 + gᵣ)^(n − 1), simulated until cash reaches zero Burn multiple = net burn ÷ net new ARR
Runway is how long your cash lasts at the current rate of spending. Gross burn is everything you spend in a month; net burn subtracts the cash coming in, and it is net burn that empties the bank. With flat figures runway is cash ÷ net burn. If revenue or costs are growing, the calculator steps through month by month, which is why growing revenue can stretch runway far beyond the simple division, or reach break-even. The burn multiple, net burn ÷ net new ARR, shows how much cash each unit of new recurring revenue costs; lower is more efficient. Real cash flow is lumpier than any average, so leave a margin before the date shown.
Your numbers, step by step
About the Runway calculator
This runway calculator shows how long your cash lasts. Enter the cash in the bank, your expenses a month and your revenue a month to get gross burn (everything you spend), net burn (spending minus cash coming in), the months of runway and the approximate date the cash runs out from the start date you pick. If revenue or costs are growing, add a monthly growth rate for each and the calculator steps through month by month instead of dividing, and tells you if revenue catches up with costs before the money runs out. Enter the month's net new annual recurring revenue to get the burn multiple, a measure of how efficiently burn turns into growth. Founders and finance teams use it to plan hiring and decide when to raise money, with every step of the working shown.
How to use it
- Enter the “Cash in the bank” today.
- Enter your “Expenses a month” and “Revenue a month”.
- Set “Starting from” to the date your cash figure applies to.
- Optionally add “Revenue growth a month” and “Expense growth a month” to simulate changing figures.
- Enter the “Net new ARR this month” to get the burn multiple.
Worked example
A start-up has 450,000 in cash, spends 65,000 a month and brings in 25,000 a month. Gross burn is 65,000 and net burn is 65,000 − 25,000 = 40,000, so runway is 450,000 ÷ 40,000 = 11.25 months, and from 1 November 2026 the cash runs out around 9 October 2027. Adding 20,000 of net new ARR in the month gives a burn multiple of 40,000 ÷ 20,000 = 2. If revenue grew 8% a month instead, it would cover costs from month 14, with 144,428.16 still in the bank after 12 months.
Updated
Questions people ask
How do I calculate cash runway?
Divide the cash you have by your net burn, which is monthly expenses minus monthly revenue. 300,000 of cash with a net burn of 25,000 a month lasts 12 months.
What is the difference between gross burn and net burn?
Gross burn is everything you spend in a month. Net burn subtracts the cash coming in from customers, and it is net burn that decides how quickly the bank balance falls.
What is the burn multiple?
Net burn divided by net new annual recurring revenue for the same period. A burn multiple of 2 means 2 of cash was spent for each 1 of new ARR; lower means more efficient growth.
Why does revenue growth change runway so much?
Each month's net burn shrinks as revenue grows, so the cash falls more slowly and may stop falling. A simple division misses this, which is why the calculator simulates month by month.
How accurate is the zero-cash date?
It assumes steady averages, while real months bring one-off costs, late payments and seasonal swings. Leave a margin, update it with actual figures, and talk to an accountant or financial adviser before major funding decisions. To see your monthly cash flow in detail, try the cash flow calculator.