FIRE Calculator – Coast FIRE and Retirement Number
Estimate your FIRE number (plus Lean, Fat and Coast FIRE variants), how many years it will take to get there, and the age you reach financial independence. Enter your savings, spending, expected return and safe withdrawal rate.
Find Your FIRE Number and Retirement Timeline
Formula of the FIRE Calculator – Coast FIRE and Retirement Number
Frequently Asked Questions
How do I calculate my FIRE number by hand?
Divide your expected annual spending in retirement by your safe withdrawal rate (SWR), expressed as a decimal. The formula is \( \text{FIRE number} = \frac{\text{annual spending}}{\text{SWR}} \). For example, with spending of 40,000 and a 4% SWR: \( 40000 \div 0.04 = 1{,}000{,}000 \). This is the 25x rule (25 years of spending multiplied out). Want a leaner lifestyle? Multiply spending by 0.7 first; for a lavish one, use 1.5.
What is a good safe withdrawal rate to use?
The classic 4% rule comes from the Trinity study, which found that a 4% withdrawal lasted 30 years in most historical US scenarios. Retiring very early (50 years or more of retirement), poor sequence-of-returns luck, high fees, or non-US portfolios argue for 3–3.5%, which raises your FIRE number. Remember these are planning heuristics, not guarantees — many early retirees adjust spending in down markets, and a fee-only financial advisor can sanity-check your assumptions.
How is Coast FIRE different from regular FIRE?
Regular FIRE means you already have the full retirement number saved. Coast FIRE means you have enough invested today that, with no further contributions, compounding alone carries you to your FIRE number by your target age. The threshold is \( \text{FIRE number} \div (1+r)^{n} \), where \( n \) is the years until that age. You still cover living expenses from your paycheck — you just stop adding to investments.
Should I enter a nominal or real (inflation-adjusted) return?
Enter a real return — what you expect after inflation. That keeps every result in today's dollars, so your FIRE number 20 years from now buys what it buys now. Global stocks have historically returned roughly 5–7% real long term; bonds are much lower. If you instead enter a nominal figure like 10%, the calculator will understate the savings you need, because your projected spending would actually grow with inflation.
What assets count toward my FIRE number?
Count invested assets: retirement accounts, index funds, brokerage holdings, and other liquid investments you can safely draw from. Generally exclude your home equity (you need somewhere to live), emergency cash (not invested), and physical possessions. Young retirees should also check withdrawal rules: money in traditional retirement accounts may face early-withdrawal penalties before age 59½ in the US, so account accessibility and taxes matter as much as the headline total.
Why does the same savings rate give different timelines for people?
Because your timeline depends on your spending relative to income and what you already have invested. Someone saving 25% of 200,000 reaches a 40,000-spending FIRE number far faster than someone saving 25% of 60,000, even if both live identically in retirement. Starting assets compound too: at a 5% real return, existing investments roughly double every 15 years, so head start matters more the earlier you begin.
What are the most common mistakes when planning for FIRE?
Top errors: using nominal returns without inflation (silently shrinking your target's purchasing), picking a 4% SWR for a 50-year retirement, ignoring healthcare and insurance costs before Medicare age, forgetting taxes on withdrawals, and assuming constant returns when crashes arrive early in retirement (sequence-of-returns risk). Also revisit your plan annually — spending creep, children, or moving cities can shift your FIRE number significantly.