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FIRE calculator

Financial Independence, Retire Early. Use the 4% rule to find your target portfolio, your years to FIRE, and the Coast FIRE threshold where compounding alone gets you there.

Calculator forecast

Logic updated April 2026

This calculator estimates how long it will take to reach Financial Independence, Retire Early (FIRE) — the point where your investment portfolio is large enough to fund your annual expenses indefinitely from withdrawals alone. It uses the 4% rule (and any safe withdrawal rate you nominate) to convert annual expenses into a target portfolio, then iterates year by year until your projected balance reaches that target.

How this is calculated

Formula 

FIRE number = annualExpenses ÷ (safeWithdrawalRate / 100) ; balance(year+1) = balance(year) × (1 + r) + annualSavings

Step-by-step

  1. Calculate the FIRE number by dividing annual expenses by the safe withdrawal rate (4% SWR = 25× expenses)
  2. Calculate annual savings as annualGrossIncome × (savingsRate / 100)
  3. If current savings already exceed the FIRE number, mark as already FIRE and stop
  4. Otherwise, iterate year by year: grow the balance at the expected return, then add annual savings at year-end
  5. Stop the year the balance first reaches the FIRE number — that's the years to FIRE
  6. Coast FIRE = FIRE number ÷ (1 + r)^yearsToFire — the lump sum needed today to grow into the FIRE number on time without further contributions
Rounding mode
ROUND_HALF_UP
Precision
20-digit internal precision (Decimal.js), rounded to 2 decimal places for display
Logic last reviewed

Assumptions & limitations

What this calculator assumes

  • FIRE number = annual expenses ÷ (safe withdrawal rate / 100)
  • Annual savings = annual income × savings rate, treated as flat dollars across the projection
  • Annual contributions are added at year-end after the existing balance compounds for the full year
  • Years to FIRE is the first year the portfolio first reaches the FIRE number
  • Coast FIRE is the lump sum needed today to reach FIRE on time without further contributions
  • Inflation on expenses is not compounded into the FIRE number — expenses are treated as the target spending in real terms

What this calculator doesn’t account for

  • Does not model taxes on contributions, growth, or withdrawals
  • Does not factor in sequence-of-returns risk — early bear markets in retirement can force a lower withdrawal rate
  • Does not account for variable income, career breaks, or windfalls
  • Does not adjust expenses for life-stage changes (children, healthcare, mortgage payoff)
  • The 4% rule is a planning heuristic from a single-jurisdiction historical dataset — your jurisdiction's tax and asset mix may justify a different rate

Worked example

A 35-year-old with $50,000 saved and $80,000 of annual gross income wants to know how long until FIRE if they save 30% and earn 7% real returns, withdrawing at 4%.

Input Value
Current savings $50,000
Annual gross income $80,000
Annual expenses $45,000
Savings rate 30%
Expected return 7%
Safe withdrawal rate 4%

FIRE number: $1,125,000 — Years to FIRE: ~22 — Coast FIRE: ~$254,000

FIRE number = $45,000 ÷ 0.04 = $1,125,000 (25× annual expenses). Annual savings are $24,000 (30% of $80,000). Starting from $50,000, growing at 7% per year, and adding $24,000 each year-end, the balance crosses $1,125,000 around year 22. The Coast FIRE figure means $254,000 invested today would grow into the full FIRE number in 22 years even without further contributions.

Frequently asked questions

What is FIRE?

FIRE stands for Financial Independence, Retire Early — a movement built around saving aggressively enough that investment income covers your living costs decades before traditional retirement age. Variants include Lean FIRE (low expenses, smaller portfolio), Fat FIRE (high expenses, larger portfolio), and Coast FIRE (front-loaded savings that grow without further contributions).

What is the 4% rule?

A planning heuristic that says you can withdraw 4% of your initial portfolio in year one and adjust that amount for inflation each subsequent year, with a high probability of the portfolio lasting 30+ years. The corollary is that you need 25× your annual expenses to retire — that's the FIRE number this calculator uses by default.

How much do I need to retire early?

At 4% SWR, 25× your annual expenses. At 3% SWR (more conservative for very long retirements), 33× expenses. At 5% SWR (aggressive), 20× expenses. The lower your expenses, the smaller the target — which is why FIRE communities focus heavily on the savings rate rather than the income figure. Cutting $5,000 of annual spending lowers the FIRE number by $125,000.

What is sequence of returns risk?

The risk that bad market returns cluster early in retirement, when your portfolio is largest and withdrawals do the most damage. Two retirees with the same average return over 30 years can end up with very different outcomes if one happened to retire just before a bear market. The 4% rule is based on historical worst-case sequences, but it's not guaranteed.

Is the 4% rule still valid?

It's debated. Some researchers argue current valuations and bond yields justify 3.3–3.7%; others point out that the original studies were conservative and 4% has historically left most portfolios with more money at the end than the start. For planning purposes, 4% is a reasonable starting point — adjust the SWR input in this calculator to test a range of assumptions.

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