The calculator
Runway is the simplest number in company finance and the one most often quoted wrongly, because "burn" sometimes means everything leaving the bank and sometimes means the gap between money in and money out. This calculator uses the second, which is the one that predicts the zero date.
Enter a balance and a typical month to see net burn, runway and the zero date.
Nothing you type leaves this page: no account, no network request, nothing saved.
How the number is worked out
Net burn is monthly cash out minus monthly cash in. If more comes in than goes out the figure is negative, you are cash-generative, and runway is not a constraint.
Runway is your current cash balance divided by net burn, which answers "how many months until the balance is zero" under the flat assumption that next month looks like this one.
The zero date is today plus that many months. It moves the moment any input moves, which is exactly why it is worth recalculating whenever a hire, a renewal or a large invoice lands.
What the flat assumption hides
A single month repeated twelve times is a useful sanity check and a poor forecast. Real cash movement is lumpy: annual software renewals, tax payments, payroll months with three pay runs, a customer who pays on sixty days rather than thirty.
It also assumes revenue is flat, which is the assumption a growing company least wants to make and a shrinking one least wants to ignore.
The fix is not a better single number — it is a month-by-month forecast where each line can differ, so the months that actually break are visible before they arrive.
When to look at this number
Before committing to a hire, because a salary is a permanent change to net burn and a signing bonus is not.
Before starting a raise, so the process is timed against the runway rather than against optimism.
At every month-end, because runway calculated once and never revisited is a number about the past.
Frequently asked questions
Is anything I type here sent anywhere?
No. The calculator is a few lines of JavaScript running in your browser. Nothing is transmitted, nothing is saved, and closing the tab discards it. You do not need an OGUM account to use it.
Should burn include or exclude revenue?
This calculator uses net burn: cash out minus cash in. Gross burn (everything leaving the bank, revenue ignored) is a useful number for a cost conversation, but it understates runway for any company with revenue, sometimes badly.
What does the full OGUM task add?
The 12-Month Cash-Flow Forecast task models each of the next twelve months separately — receipts, payments, timing and the assumptions behind each line — and returns a working spreadsheet you can change and re-run. This page gives you one number from one flat month.
Related tasks
Turn one month into twelve
The 12-Month Cash-Flow Forecast task models every month separately and returns a spreadsheet with live formulas.
Start the brief — 12-Month Cash-Flow Forecast⚡ 250 credits · XLSX · one free revision · 100 free credits on sign-up. See what the task includes.