About The FIRE Number

The FIRE Number is a set of free, focused calculators for people planning their Financial Independence and Early Retirement journey. No fluff, no email capture, no paywalls — just precise math and clean charts.

Our approach

Every calculator on this site uses the formulas the FIRE community has converged on over the past two decades — the 4% rule, present-value discounting for Coast FIRE, and year-by-year compounding for retirement-age projections.

All figures are expressed in today's dollars using real (inflation-adjusted) returns. This means you don't need to add a separate inflation layer — a 5% real return is already net of ~3% inflation, and the dollar amounts produced are in today's purchasing power.

Key assumptions

• Returns are real (inflation-adjusted): default 5–7% in the calculators, reflecting long-term historical US stock market performance minus inflation.
• Withdrawals are annual: the projection models add contributions and apply returns once per year. Monthly compounding would give slightly different numbers, but the long-run difference is small.
• 4% withdrawal rate default: rooted in the Trinity Study. Users can adjust this to 3–8% depending on their situation.
• No taxes: the calculators don't account for taxes on withdrawals. In tax-advantaged accounts (Roth IRA, 401k) the impact varies significantly; consult a tax adviser.
• Constant returns: the year-by-year simulation uses a steady return rate, not historical variability. Sequence-of-returns risk is not modelled.

Disclaimer

The FIRE Number calculators are for educational and informational purposes only. Nothing on this site constitutes financial, tax, legal, or investment advice. Past market performance does not guarantee future results. Financial projections are inherently uncertain and depend on many factors this site cannot model.

Please consult a qualified financial professional before making significant financial decisions.

Shareable links

Calculator inputs are encoded in the page URL when you adjust sliders. You can copy the URL (or use the "Copy shareable link" button) to share your exact scenario with a partner, financial adviser, or the FIRE community. No data is stored on our servers — the parameters live only in your browser's URL.

Contact

Found a bug or have a suggestion? Head to our Contact page — we'd love to hear from you.