Cash & runway
Cash Runway Calculator
Turn cash, monthly revenue, and monthly costs into months of runway, then see what a revenue drop or cost rise does to that number.
Decision: How many months of cash remain if revenue falls or costs rise?
This tool runs in your browser. FounderMage does not send the numbers you enter to our servers.
Result
Base runway
Base runway: 8 months
Net burn $30,000.00
Revenue −20%
Revenue −20%: 7.1 months
Costs +15%
Costs +15%: 6.4 months
Net burn needed for 12 months
Net burn needed for 12 months: $20,000.00
How to read the result
A shorter runway means the cash you entered is consumed faster at that net burn. It is not a recommendation to raise, cut, or hire.
Calculated facts
Totals and thresholds come only from the values on this page. They describe the math, not what you should do.
Still a judgment call
Risk, timing, customers, and judgment stay outside the calculator. A stronger number can still be the wrong path.
Methodology
Net burn is monthly costs minus monthly revenue. When net burn is positive and cash is zero or greater, runway is cash ÷ net burn, so zero cash is zero months. Cash that is already negative is not a future runway. Negative net burn means cash is increasing. Zero net burn has no finite runway. A revenue shock multiplies revenue by (1 − shock). A cost shock multiplies costs by (1 + shock). When cash is zero or greater, burn needed for a target is cash ÷ target months. That figure is omitted when cash is already negative.
Assumptions
- Revenue and costs stay at the monthly figures you enter inside each case.
- No taxes, collections delay, or debt service unless included in costs.
Examples
Simple net burn
$240,000 cash, $20,000 revenue, $50,000 costs is $30,000 net burn and 8.0 months of runway.
Revenue drop
The same $240,000.00 cash and $50,000.00 costs with revenue 20% lower ($16,000.00) is $34,000.00 net burn and 7.1 months. The base case is $30,000.00 net burn and 8 months. Each case is a constant monthly run-rate, not a forecast.
How to use this tool
- Enter cash on hand, monthly revenue, and monthly costs.
- Set a revenue-drop and cost-rise shock if you want scenarios.
- Read base runway and the burn that would be needed to hit a target number of months.
Limitations
- Growth is not forecast. Each case is a constant monthly run-rate.
- This is not accounting, tax, or fundraising advice.
Questions
- Is runway the same as gross burn?
- No. Runway uses net burn: monthly costs minus monthly revenue. Gross burn ignores revenue and understates remaining months when you have sales.
- What if revenue is higher than costs?
- Net burn is negative. The tool reports that cash is increasing instead of inventing a finite runway.