Runway is how many months your company can operate on the cash it has today. For SaaS and AI startups, where compute and payroll grow alongside revenue, it is the number investors and boards ask about first.
Free tool
Cash runway calculator
See your monthly net burn, how many months of cash you have left and the month you would run out, with growth built in.
A simple projection that assumes steady monthly growth; real runway depends on collections timing, one-off costs and financing. Results are estimates for general information only, not legal, tax or financial advice. Confirm them with your own CPA, tax adviser or attorney before making decisions. Using this tool does not create a client relationship with Catching Numbers Inc.
How runway is calculated
Net burn is monthly expenses minus monthly revenue. Runway is cash divided by net burn, adjusted month by month for the growth rates you enter. If revenue grows faster than costs, burn shrinks and runway extends; if compute or hiring grows faster, it shortens.
Ways to extend your runway
- Collect receivables faster and move annual customers to upfront billing
- Use cloud and AI credits fully and review compute commitments every quarter
- Match hiring to revenue milestones, not calendar dates
- Track gross margin monthly so model and hosting costs don’t quietly erode it
- Keep a 13-week cash forecast so there are no surprises
Frequently asked questions
How much runway should a startup have?
Many founders aim for 18 to 24 months after a raise, and start raising again with at least 6 to 9 months left, because fundraising usually takes longer than planned.
What is the difference between gross burn and net burn?
Gross burn is total cash spent each month. Net burn is gross burn minus the cash your customers pay you. Runway is based on net burn.
Can you build a cash forecast for us?
Yes. Our fractional CFO service includes 13-week cash forecasts, budgets and runway scenarios, built on books we close every month.
Get a runway number you can put in front of investors
We close your books every month and build the forecast on top of them.