Phase 1 · Core Sovereign Layer
Startup Runway Calculator
A frozen cash ÷ burn number lies to you. Model revenue growth against expense creep month by month and see the date your runway truly ends — or whether you're default alive.
Under the hood
The math, fully exposed
We don't freeze your burn. Starting from today, each month is simulated until cash runs out or you reach breakeven:
Static runway = cash ÷ (expenses − revenue)
Each simulated month:
cash = cash − (expenses − revenue)
revenue = revenue × (1 + revenue growth)
expenses = expenses × (1 + expense growth)
cash = cash − (expenses − revenue)
revenue = revenue × (1 + revenue growth)
expenses = expenses × (1 + expense growth)
Default alive when revenue ≥ expenses before cash ≤ 0
- Why simulate: a static number assumes nothing changes. In reality a 8%/mo revenue ramp can add many months of runway — or runaway hiring can erase them. The simulation captures the compounding both ways.
- Breakeven beats balance: if revenue growth crosses expenses before zero, you're default alive — the most powerful position a founder can hold in a fundraise.
- The danger of expense creep: when expense growth outpaces revenue growth, net burn widens every month and runway collapses faster than the static figure implies.
Your directives
What to do next, based on your numbers
Adjust the sliders to generate tailored recommendations.
Answers
Frequently asked questions
How is startup runway actually calculated?
The naive formula is cash ÷ net monthly burn. But that assumes burn is frozen. This tool simulates each month forward: revenue compounds at your growth rate, expenses creep at theirs, and we subtract the changing net burn from cash until it hits zero — or until revenue overtakes expenses and you become "default alive."
What does "default alive" mean?
Coined by Paul Graham: a startup is default alive if, on its current trajectory, revenue growth reaches profitability before the cash runs out. If this calculator shows you crossing breakeven before zero, you control your own destiny and do not strictly need to raise.
How much runway should I have before raising again?
A common rule of thumb is to raise with 12–18 months of runway remaining, because fundraising itself takes 3–6 months and you want to negotiate from strength, not desperation. Under 6 months is a danger zone that weakens your leverage with investors.
Why does my dynamic runway differ from cash ÷ burn?
If your revenue is growing, dynamic runway is longer than the static snapshot because net burn shrinks each month. If your expenses are growing faster than revenue, dynamic runway is shorter. The gap between the two numbers is exactly the value of your growth trajectory.