Understanding your cash runway results
Startup and venture-finance convention commonly treats 18 or more months of runway as comfortable, since it typically allows time to reach the next milestone or raise additional financing before cash runs critically low.
| Runway | Common characterization |
|---|---|
| 18+ months | Healthy — commonly cited as a comfortable buffer to reach milestones or complete a financing process. |
| 9–18 months | Watch — enough time to plan, but financing or cost decisions typically need attention soon. |
| Under 9 months | Critical — cash reaches zero soon at the current spending pace unless burn is reduced or new cash comes in. |
- This calculator assumes monthly burn stays constant — actual runway will differ if spending increases, decreases, or if revenue growth changes the net cash outflow.
- The 18-month comfortable-runway convention is a commonly cited rule of thumb in startup and venture financing, not a universal or guaranteed threshold; the right runway target depends on the specific business, its financing environment, and its milestones.
What is cash runway?
Cash runway is the length of time — usually expressed in months — that a business can continue operating at its current net spending rate before its cash balance is exhausted. It is calculated by dividing the current cash balance by the monthly burn rate (the net amount of cash being spent each month).
Runway is one of the most closely tracked metrics for early-stage and venture-backed companies, since it directly indicates how much time remains to reach profitability, hit a growth milestone, or complete a financing round before cash runs out.
A runway figure is only as reliable as the burn rate used to calculate it — if spending or revenue is expected to change materially, the runway estimate should be recalculated using the updated burn rate rather than relying on a historical average.
How to use this cash runway calculator
- Enter your current cash balance.
- Enter your monthly burn rate — the net amount of cash your business spends each month (use the burn rate calculator first if you need to derive this from cash-balance history).
- Read the resulting runway in months and years, along with whether it falls in the healthy, watch, or critical range.
The formula behind cash runway
Runway in months is the current cash balance divided by the monthly burn rate. For example, with $400,000 in cash and a monthly burn rate of $25,000, runway is $400,000 ÷ $25,000 = 16 months.
Runway in years simply divides the months figure by 12, giving 16 ÷ 12 ≈ 1.33 years in this example.
Common mistakes
- Using a burn rate from an unusually low- or high-spend month rather than a representative average, which skews the runway estimate.
- Not updating the runway estimate after a material change in spending or revenue — runway calculated from stale burn-rate figures can be materially wrong.
- Treating runway as a fixed date rather than a moving estimate that should be recalculated regularly as cash balance and burn rate change.
- Ignoring planned future expenses (e.g., a hiring plan or a large upcoming purchase) that would increase burn rate and shorten runway beyond what the current burn rate implies.
Domande frequenti
How is cash runway calculated?
Cash runway is calculated by dividing the current cash balance by the monthly burn rate — the net amount of cash the business spends each month. The result estimates how many months of operation remain at the current spending pace before cash reaches zero.
How much runway should a startup have?
Eighteen or more months of runway is a commonly cited comfortable buffer in startup and venture financing, since it generally allows time to reach a milestone or complete a financing process. This is a widely used convention rather than a guaranteed or universal requirement, and the appropriate target varies by company and financing environment.
What is the difference between burn rate and runway?
Burn rate is the pace of cash consumption per month; runway is the resulting length of time the current cash balance would last at that burn rate. Runway is derived directly from burn rate and cash balance — a lower burn rate relative to cash on hand produces a longer runway.
Does cash runway account for future revenue growth?
This calculator uses a single monthly burn rate figure and does not model changing revenue or spending over time. If revenue is expected to grow or costs are expected to change, runway should be recalculated periodically using an updated burn rate rather than relying on a single static estimate.
Fonti
- Y Combinator. Startup Library — managing runway and burn rate. ycombinator.com.
- U.S. Small Business Administration. Manage your finances — cash flow guidance. sba.gov.
- Brealey RA, Myers SC, Allen F. Principles of Corporate Finance. 13th ed. McGraw-Hill Education, 2020.