Burn Rate & Runway Calculator — See Your Zero-Cash Date and Cash Chart

Free burn rate and runway calculator for startups and SaaS: zero-cash date, default-alive test, scenarios, fundraising timing, and CSV import. Private, in-browser.

What it does

Enter your cash, revenue and monthly expenses and this calculator shows how many months of runway you have, the date your cash reaches zero, and a month-by-month cash chart. It tells you whether you are default alive — whether revenue overtakes costs before the money runs out — and how much you would need to raise to reach a target runway.

You can model growth, churn and expansion, add dated events such as a funding round or a new hire, compare pessimistic and optimistic scenarios, and import real monthly numbers from a CSV so the forecast starts from your actuals.

Burn rate and runway, defined

Gross burn is everything you spend each month, including cost of revenue. Net burn is gross burn minus revenue, so it is the cash you actually lose. Runway is how long your cash lasts.

The quick version is cash ÷ net burn: 100,000 of cash and 10,000 of net burn is 10 months. That shortcut is shown for comparison, but it assumes nothing changes. Real businesses grow revenue, add costs and raise money, so the headline runway here comes from a month-by-month model.

How it works

Monthly simulation. Each month, revenue grows by your rate (or, in SaaS mode, changes by expansion minus churn and adds new MRR). Every expense line grows at its own rate, cost of revenue is taken as a share of revenue, and events land in the month of their date. The balance at each month end is tracked for up to ten years.

The zero-cash date. Runway ends when the balance first crosses zero. The exact crossing is interpolated inside that month, so 25,000 of cash against 10,000 of burn gives 2.5 months, not “3”, and the date reflects that. Calendar arithmetic is exact, including month lengths and leap years.

Default alive. If revenue overtakes costs before cash runs out, the model says so and reports the break-even month and your lowest balance along the way. If the runway ends first, you get the date, the shortfall, and whether break-even would have arrived too late.

Fundraising timing. Set how long a raise takes to close (6 months by default, with 3, 9 and 12 as quick presets) and the runway you want afterwards (18 months by default). The tool gives the date you should start raising, the amount needed if the money landed today, and the amount needed if it lands when the process closes, rounded to two significant figures for sanity.

Private by design. Nothing is uploaded. Inputs are saved in your browser, and imported files are kept in its local storage so a refresh doesn’t lose them. Each file can be deleted individually, or everything cleared, from the Saved tab.

How to use it

Runway tab: enter cash in the bank, current monthly revenue and your expense lines (payroll, tools, marketing, and so on). Choose a simple growth rate or the SaaS model with new MRR, churn and expansion. Read the runway, zero-cash date and chart.
Plan & raise tab: set your time-to-close and target runway, then add dated events — a raise, a hire, a price rise, a one-off cost. Adjust the pessimistic and optimistic scenario shifts and check the sensitivity grid to see how much cutting spend or improving growth buys you.
Import actuals tab: drop in a CSV with month, revenue and expenses (optionally cash, new MRR and churned MRR) and tick “use these actuals”. The forecast then starts from your real numbers, with your history drawn on the chart.
Share it: copy the one-line summary for an investor update, download the chart as an image, or export the monthly schedule as CSV.

If your bookkeeping export is untidy, clean it with the CSV cleaner before importing, and use the CSV chart tool to look at other columns of the same file. To see how many units or customers it takes to stop the burn, pair this with the break-even calculator.

Importing your actuals

The importer accepts commas, semicolons, tabs and pipes, quoted fields, and both decimal points and decimal commas. Months can be written as 2026-05, 05/2026, “Jan 2026”, “Jan-26” or a full date, and ambiguous dates like 03/04/2026 can be set to month-first or day-first. Duplicate months use the last row, out-of-order rows are sorted, missing months are flagged, and unreadable rows are listed by row number instead of being silently skipped.

From the last few months (you choose 1 to 12) it derives your latest revenue, average expenses, growth or churn and new MRR, and, if your file has a cash column, your starting balance. If not, the tool uses the cash figure you enter as the balance at the end of your last month.

Frequently asked questions

How do I calculate runway?

Divide cash by net burn for a rough answer. For a better one, model growth and costs month by month, which is what this tool does. It reports both so you can see how much growth, hiring and planned events change the answer.

What is a good runway for a startup?

Under 6 months is urgent, 6–12 months is tight, and 12 months or more is comfortable. The results use those bands. Fundraising often takes 3 to 6 months or longer, so many founders aim to start raising with at least 12 months in hand.

What does “default alive” mean?

It means that if nothing changes except the growth you’ve assumed, revenue overtakes costs before the cash runs out, so the company survives without new funding. “Default dead” means it doesn’t. The result is only as good as your growth assumption, which is why the scenarios and sensitivity grid are included.

What is burn multiple?

Burn multiple is net burn divided by net new annual recurring revenue. Lower is better; a figure under 2× is generally considered efficient. It appears when you are burning cash and revenue is growing.

How much should I raise?

The Plan & raise tab shows the amount that keeps your balance above zero for your target runway, both if the money arrives today and if it lands when the raise closes. Treat it as a floor: it reflects your assumptions, not a guarantee, so many founders add a buffer.

Is my financial data sent anywhere?

No. Everything runs in your browser. Data stays on your device in the browser’s own storage, and you can remove imported files individually or clear everything.