Startup Runway Calculator
Months of runway from cash balance and burn rate, and the effect of a change in either.
Runway Calculator
Details
Runway and net burn
Runway is how long the cash lasts at the current net burn — cash out minus cash in, not gross spending.
runway (months) = cash balance ÷ net monthly burn net burn = monthly costs − monthly revenue
- cash balance
- Cash actually available, excluding committed-but-unreceived funding
- monthly costs
- All cash out: salaries, contractors, tools, rent, taxes
- monthly revenue
- Cash actually collected, not invoiced
Worked example
- Cash balance
- 600,000
- Monthly costs
- 95,000
- Monthly revenue
- 25,000
- Net burn
- 70,000
≈ 8.5 months of runway
Use collected revenue, not booked or invoiced. Runway calculated on invoices you have not been paid for is optimistic in exactly the situation where optimism is most expensive.
Managing runway
- Start raising at 9–12 months, not 3 —A raise commonly takes 3–6 months. Starting with under six months of runway means negotiating from a position everyone can see, and terms reflect it.
- Model a downside case —What is the runway if revenue stays flat and one large customer leaves? That is the number to plan against.
- Track burn multiple, not just burn —Net burn divided by net new ARR. It tells you what growth is costing, and investors will ask.
- Know your default-alive date —The month you would reach profitability on current trajectory without raising again. If it is inside your runway, you have far more optionality than the raw months suggest.
- Salaries dominate —For most early companies, people are 70–80% of burn. Meaningful runway extension almost always involves hiring pace, not tool spend.
- Cutting late is worse than cutting early —A cut made with nine months of runway is a decision. The same cut with three months is a crisis, and it costs more in trust and severance.
About
The Runway Calculator tells founders and CFOs exactly how many months their startup can operate before running out of cash — given current cash on hand, total monthly expenses (gross burn), and monthly revenue. The tool computes net burn (gross burn minus revenue), runway in months, the projected cash-out date, and the burn multiple (net burn divided by revenue), which investors use to gauge capital efficiency. If net burn is zero or negative, the startup is cash-flow positive and has unlimited runway. Tracking runway is one of the most critical responsibilities of any startup — most venture-backed companies aim for at least 18 months of runway before beginning their next fundraise.
How to use
- 1 Enter your current cash and bank balance — the total liquid funds available.
- 2 Enter your total monthly expenses (gross burn) — include payroll, rent, cloud costs, marketing, and all other operating costs.
- 3 Enter monthly revenue — use 0 if you are pre-revenue.
- 4 Review runway months, the projected cash-out date, net burn, and burn multiple.
- 5 Experiment with different revenue or expense scenarios to understand what changes extend your runway the most.
- What is burn rate and why does it matter?
- Burn rate is the rate at which a company spends its cash reserves. Gross burn is total monthly operating expenses. Net burn is gross burn minus monthly revenue — the actual cash consumed each month. Runway = Cash on Hand ÷ Net Burn. Burn rate matters because it determines how long you have to reach profitability or raise more capital. Most investors want to see at least 18 months of runway after a funding round.
- What is the burn multiple and what is a good number?
- Burn multiple = Net Burn ÷ Net New Revenue. It measures how much cash you burn to generate each dollar of new revenue. A burn multiple below 1× is excellent (you spend less than $1 to generate $1 of new revenue). 1–2× is good. Above 2× is concerning. Above 4× is typically considered unsustainable for a growth-stage company. It is a capital efficiency metric that investors use alongside ARR growth to evaluate startups.
- When should I start fundraising relative to my runway?
- The conventional wisdom is to start fundraising when you have 9–12 months of runway remaining. A typical seed or Series A round takes 3–6 months to close from first meeting to money in the bank. Starting too late (under 6 months remaining) puts you in a weak negotiating position and risks missing payroll. Starting too early (over 18 months) means you may not have enough traction metrics to command a good valuation.
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