Burn Rate & Runway Calculator
Walk cash down month by month with optional revenue compounding, gross burn, net burn, runway headline, and a four-row scenario table.
100% client-side. Inputs stay in your browser (ons-burn-rate-inputs).
Model net burn with optional month-over-month revenue growth, then read runway from a month-by-month cash walk, not a single static divisor when growth is on.
Inputs
You have about 17.0 months of runway.
Naive constant-burn runway (month-1 net burn only): 12.5 months, iteration above accounts for revenue growth month by month.
Cash balance
$500,000
Gross burn
$60,000
Net burn (month 1)
$40,000
Break-even month
Month 24
Cash balance over time
Orange line marks the first month where modeled revenue meets or exceeds operating costs.
Scenario comparison
Same growth assumption; costs or starting revenue shift per row.
| Scenario | Net burn (month 1) | Runway |
|---|---|---|
| Current plan | $40,000 | 17.0 mo |
| Operating costs −10% | $34,000 | 10+ years |
| Operating costs −25% | $25,000 | 10+ years |
| Monthly revenue +20% | $36,000 | 10+ years |
Under about 12 months of simple (constant) net burn is a common healthy SaaS growth benchmark, your iterated runway above is the headline when growth is on.
How this tool works
The calculator starts with two numbers: what you spend each month (gross burn) and what you earn (revenue). Net burn = monthly costs minus monthly revenue. A simple runway estimate divides your cash balance by net burn, but simple division ignores revenue growth. The tool handles this by iterating forward month by month: it applies your growth rate to revenue each month, recalculates net burn, and subtracts it from remaining cash until the balance hits zero or 120 months. With revenue growth factored in, runway extends beyond the simple estimate because each month the burn gets smaller. The scenario comparison table runs the same month-by-month projection under four conditions: current burn, costs cut 10%, costs cut 25%, and revenue up 20%. If revenue already exceeds costs, the calculator shows: Break-even. Runway is indefinite.
Worked example
Cash balance $500,000. Monthly revenue $20,000. Monthly costs $60,000. Revenue growth 5% per month. Simple runway: $500,000 / $40,000 = 12.5 months. With 5% growth applied month by month, cash runs out at approximately month 16 instead of 12.5. Break-even (where revenue reaches $60,000) occurs around month 23, but cash runs out first at month 16. Cutting costs 25% extends runway to approximately 25 months. Revenue up 20% extends to approximately 18 months.
Frequently asked questions
What is burn rate?
Burn rate is how much cash your company spends beyond what it earns each month. Gross burn is your total monthly expenses. Net burn subtracts your revenue from expenses. A startup with $80,000 in costs and $30,000 in revenue has a net burn of $50,000 per month.
What is a healthy runway for a startup?
18 to 24 months is the standard recommendation from most venture investors. This gives you enough time to hit key milestones and start a fundraise 6 to 9 months before you run out. Below 12 months, you should already be fundraising or cutting costs. Use this metric consistently over time to track improvement rather than optimizing for a single period's snapshot.
How do I extend my runway?
Two paths: cut costs (faster effect, immediate runway extension) or grow revenue (slower but compounds over time). Most founders combine both. The scenario table in this calculator shows the impact of each approach so you can prioritize. Run the calculation monthly to track trend direction rather than relying on a single data point.
When should I start fundraising?
When you have 9 to 12 months of runway remaining. Most fundraising rounds take 3 to 6 months from first meeting to wire. Starting at 6 months or less puts you in a weak negotiating position because investors know you are running out of time. Revisit this decision as your situation changes; the right answer today may differ from the right answer in 12 months.
What is the difference between gross burn and net burn?
Gross burn is your total monthly spending regardless of income. Net burn subtracts revenue from that total. Investors care more about net burn because it reflects how fast you are actually consuming cash. A company with $100,000 gross burn and $70,000 revenue has only $30,000 net burn. Use this metric consistently over time to track improvement rather than optimizing for a single period's snapshot.
Should I include one-time expenses?
No. Burn rate measures your recurring monthly run rate. One-time costs like equipment purchases, legal fees, or moving expenses should be handled separately. If you have a large one-time expense coming, subtract it from your cash balance before entering it into the calculator. Test both approaches with real data from your business before committing to a single strategy.