Startup Runway Calculator
See how many months of runway you have, with and without revenue growth.
How this is calculated
Net burn is your monthly burn rate minus current revenue. Without growth, runway is simply cash balance divided by that net burn. With growth, revenue compounds monthly at your projected rate while burn stays fixed, and the simulation runs month by month until cash reaches zero (or revenue catches up with burn first).
Many investors apply an informal "18-month rule": after closing a funding round, they want to see the company still have around 18 months of runway remaining before it needs to raise again. This buffer accounts for the 3–6 months a fundraising process typically takes, plus margin for the business hitting milestones later than planned — a company that raises with only 12 months of runway can find itself back in fundraising mode almost immediately, with little time to show meaningful progress to new investors. For the revenue side of extending runway, see the SaaS Revenue Estimator, and for the unit economics behind sustainable growth, see the Break-even Calculator.
Frequently asked questions
- What counts as "burn rate" here?
- Your gross monthly costs — total cash going out, before subtracting revenue. Net burn (the actual monthly cash decrease) is burn rate minus current revenue, which is what determines how fast you run out.
- Why do runway estimates differ with and without revenue growth?
- Without growth, revenue is held flat at its current level — a conservative, worst-case view. With growth, revenue compounds monthly at your projected rate, which can extend runway significantly, or even mean you never run out if revenue overtakes burn before cash depletes.
- What does the chart show?
- Your projected cash balance month by month, using your projected revenue growth rate. The line turns red if the balance reaches zero within the chart's window.
- Can I use this in my own app?
- Yes — every calculator on Stupidly Clever has a matching REST API and MCP tool that runs the same underlying logic.
- What is a healthy startup runway?
- Most investors and experienced founders consider 12–18+ months of runway healthy for a venture-backed startup, since raising a new round typically takes several months and leaves little margin for error if the timeline slips. Runway below 6 months is generally considered a red flag requiring urgent action.
- What is the difference between gross burn and net burn?
- Gross burn is total cash going out each month, before subtracting any revenue. Net burn is gross burn minus revenue collected — the actual rate your cash balance is declining. Net burn is what determines runway; gross burn matters for understanding the underlying cost structure.
- How does runway affect fundraising timing?
- Fundraising itself takes time — often 3–6 months from first pitch to closed round — so founders typically aim to start raising with at least 6–9 months of runway remaining, giving buffer if the process takes longer than expected or the first attempt doesn't succeed.
- What is default alive vs default dead?
- A company is "default alive" if its current revenue growth trajectory would make it profitable before running out of cash, without needing to raise again. It's "default dead" if, at current growth and burn rates, it will run out of cash before reaching profitability — a framing popularized by Paul Graham of Y Combinator to help founders assess their real financial trajectory.