FIRE & Runway Simulator
Run thousands of Monte Carlo paths for startup runway or FIRE retirement. See ruin probability and percentile capital bands over your horizon.
- 1Fill inputs
- 2Run
- 3Copy / export
Inputs
Required fields on the left
NumPy Monte Carlo on the API — startup runway calculator and FIRE retirement simulator share the same engine.
Results
Appears after you run
Startup runway
Set burn/spend and capital, then run 10,000 paths to see survival odds and percentile capital.
From inputs to a decision
Run thousands of Monte Carlo paths for startup runway or FIRE retirement. See ruin probability and percentile capital bands over your horizon.
- 01
Choose startup runway or FIRE mode.
- 02
Enter monthly spend/burn and capital.
- 03
Set return, inflation, volatility, and horizon.
- 04
Run simulations and export CSV if needed.
Tips for better results
- Use a seed for reproducible stakeholder decks.
- Use after-tax numbers when comparing job vs side income.
- Monte Carlo outputs are probabilities, not guarantees.
Frequently asked questions
- How many simulations run by default?
- 10,000 paths on the API, with caching for identical inputs.
- Is this financial advice?
- No. It is an educational simulator. Decisions need your own advisors and assumptions.
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Why teams use this calculator
Startup runway calculator and FIRE retirement simulator share one NumPy Monte Carlo engine — useful when you need survival odds, not a single deterministic spreadsheet cell.