Startup Runway Calculator
Calculate startup runway in months. Factor in monthly burn rate and revenue to see when cash runs out.
What is Startup Runway Calculator?
A startup runway calculator determines how many months your company can continue operating before running out of cash, given current spending (burn rate) and revenue. Runway = cash balance / (monthly expenses - monthly revenue). This is the most critical metric for early-stage startups — it determines urgency for fundraising, when to cut costs, and how much buffer you have for experimentation. Running out of runway means the company dies, regardless of product quality or market fit.
How It Works
Enter your current cash balance, monthly burn rate (total expenses), and monthly revenue. Net burn = expenses - revenue. Runway = cash / net burn. The tool also models scenarios: what if you increase revenue by X%? Cut costs by Y%? It shows how each change extends or shortens your runway. For pre-revenue startups, runway = cash / burn rate (simple). The tool indicates danger zones (under 6 months), caution zones (6-12 months), and comfortable zones (12+ months).
Common Use Cases
- •Determining urgency for next fundraising round based on remaining operational months
- •Modeling the runway impact of hiring decisions (each hire reduces runway by X months)
- •Evaluating cost-cutting scenarios to extend runway through revenue trough periods
- •Presenting runway projections to investors and board members in financial updates
- •Setting revenue milestones needed to reach default alive (revenue covers expenses)
- •Planning fundraise timing — investors typically want to see 18+ months of runway post-raise
Frequently Asked Questions
What is runway?▼
The number of months your startup can operate before running out of cash, given current burn rate and revenue.
How is runway calculated?▼
Cash on hand divided by net monthly burn, where net burn is monthly cash out minus cash in. With £500,000 in the bank and £50,000 net burn, runway is 10 months. Use cash movements, not accounting profit, since the two diverge considerably.
What is the difference between gross and net burn?▼
Gross burn is total monthly cash spend. Net burn subtracts revenue, so it is the figure that actually depletes the bank balance. Quoting gross burn understates runway; quoting net burn while revenue is volatile overstates it.
How much runway should I have before raising again?▼
Conventional advice is to start raising with 12 months remaining and never let it fall below six, because a round routinely takes three to six months to close and negotiating position deteriorates sharply as cash runs short. Investors can tell when you have no alternative.
Should runway assume growth in burn?▼
Yes, if you are hiring, since burn rarely stays flat. A static calculation against a growing team is optimistic. Model a flat case and a planned-hiring case, and know the point at which you would need to freeze hiring.
What is default alive?▼
A business is default alive if, on current growth and burn, it reaches profitability before the cash runs out — and default dead if it does not. The distinction, framed by Paul Graham, matters because a default-dead company must change something rather than simply continue executing.
Related Tools
More from Calculators:
SaaS MRR Calculator
Calculate MRR, ARR, net growth, and months to target. Factor in churn and new customer acquisition.
Break-Even Calculator
Calculate your break-even point in units and revenue. Input fixed costs, variable costs, and selling price.
ROI Calculator
Calculate ROI percentage, net profit, and annualized return on investment. Simple and accurate ROI formula.