FIRE Number Calculator

FIRE FINANCE RETIREMENT
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By Checked against sources by , Founder & Architect, RECATOOLS Published Updated Last reviewed

Calculate your FIRE number (annual expenses ÷ safe withdrawal rate). Shows years-to-FIRE under three savings scenarios.

RT-FIN-172 · Finance & Money
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FIRE Number Calculator

⚠ Disclaimer: Estimates only. Not investment advice. RECATOOLS is not a licensed or registered investment adviser in any jurisdiction. Past performance does not guarantee future results. Trading and investing carry risk of partial or total loss of capital.
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What you'd spend per year in retirement
4% traces to Bengen (1994), a 30-year US finding
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Invested assets you have today
$
How much you save + invest per year
US equities returned 6.6% a year after inflation, 1900–2025 (UBS); 0 means no growth
📅 Research current as of 19 Oct 2026 · Sources: Bengen, Journal of Financial Planning (Oct 1994); Cooley, Hubbard and Walz, AAII Journal (Feb 1998); Morningstar, The State of Retirement Income: 2025; UBS Global Investment Returns Yearbook 2026. Each year the balance grows at the real return, then the year's saving is added.
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How to use the FIRE Number Calculator

Estimate your annual retirement expenses

Not today's expenses — what you'd spend per year in retirement, including healthcare, travel, kids out of the house, mortgage paid off. Most FIRE practitioners track 12 months of actual spending then adjust for known lifestyle changes.

Pick a Safe Withdrawal Rate

The 4% starting rate comes from William Bengen's 1994 paper and was corroborated by the Trinity Study (Cooley, Hubbard & Walz, 1998). In Trinity's data, 4% inflation-adjusted withdrawals over 30 years succeeded in 95-98% of historical periods for stock-heavy portfolios (50-100% stocks). For longer retirements the sources point lower: Bengen found 3%, and up to about 3.5%, lasted at least 50 years from every US start year, and Morningstar's 2025 estimate for a 40-year horizon is 3.3%.

Enter current portfolio + annual contribution

Current portfolio = invested assets only (not cash for spending, not home equity). Annual contribution = what you put into investments per year. The tool projects how many years it'll take to reach your FIRE number compounding at your real return.

Read the scenarios table

The tool computes years-to-FIRE under three saving scenarios — current pace, 50% more, and 2× current. Each year the balance grows at your real return and that year's saving is added at the end. At the default inputs that is 18 years at the current pace, 14 saving 50% more and 12 saving twice as much: the existing USD 100K keeps compounding whatever you add.

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FIRE — the math behind early retirement

FIRE — Financial Independence, Retire Early — is built on one elegant insight: if your investment portfolio can generate enough passive income to cover your annual expenses, you don't need to work for money any more. The "FIRE number" is the portfolio size that makes that math work. The shortcut formula is brutally simple: FIRE Number = Annual Expenses ÷ Safe Withdrawal Rate. At a 4% SWR, you need 25× your annual expenses. At 3.5%, you need 28.6×. At 3%, you need 33.3×. The relationship is hyperbolic — every percentage point you trim from your SWR shifts your target dramatically.

Where the 4% rule came from

The 4% rule traces to William Bengen's 1994 paper, which back-tested US stock-bond portfolios from every retirement start year since 1926 and found that 4% inflation-adjusted withdrawals never exhausted a 50/50 portfolio in under 33 years. The Trinity Study (Cooley, Hubbard & Walz, 1998) corroborated it with success rates: at 4% over 30 years, stock-heavy portfolios succeeded in 95-98% of historical periods. Bengen himself later published higher figures — 4.5% in 2020, and 4.7% in late 2025 on a broader multi-asset portfolio. Morningstar's forward-looking 2025 estimate goes the other way: 3.9% for 30 years and 3.3% for 40, at 90% confidence and before fees. All of these are US-based; none is a guarantee.

25× annual expenses is the canonical FIRE target. 33× is conservative FIRE for 50-year retirements. Both are based on historical data — neither is a guarantee.

The APAC FIRE community

FIRE has active communities across the region — Singapore's 1M65 movement and the Seedly forums are the best-known examples. But the variables differ from the US case the research was built on: (a) healthcare in many APAC countries means either private insurance or staying near major-city public hospitals, which shapes the expense estimate; (b) the long-run return record is mostly a US record — the deep multi-decade datasets put US equities around 6.6% real (UBS Global Investment Returns Yearbook 2026, 1900-2025), and comparable series for ASEAN markets are thinner, so a US-calibrated 7% real assumption may not travel; (c) stronger family financial obligations (supporting parents, education for siblings) extend the cash-needs window. The tool's real-return input is exposed precisely so you can test a more conservative number (5-6% real) against the default.

Limitations to be honest about

The 4% rule is a probabilistic guide, not a guarantee. Three failure modes: sequence-of-returns risk (bad years early do far more damage than the same years late — Bengen's worst US starts were 1966 and 1969); costs that outrun general inflation, healthcare above all, which a single real-return figure cannot see; longevity risk (the studies stop at 30 years, which does not fit someone stopping work at 40). The levers that change the arithmetic: spend less after bad years, keep some income in the early years, and use a lower rate for a longer horizon.

Where the 4% rule came from, and where it breaks

01

The 4% rule started with William Bengen's 1994 paper; the Trinity Study (1998) corroborated it. Its authors — Cooley, Hubbard and Walz — were professors of finance at Trinity University, San Antonio, Texas.

02

The FIRE multiplier: at 4% SWR, you need 25× annual expenses. At 3.5%, 28.6×. At 3%, 33.3×. Each percentage point matters enormously.

03

Mr. Money Mustache's January 2012 post put a 50% savings rate at about 16 years from zero, assuming 5% returns after inflation and a 4% withdrawal rate. This calculator's year-end arithmetic gives 17 years at 5% and 15 at 7%.

04

FIRE has subtypes: Lean FIRE (lower spend, faster), Fat FIRE (higher spend, more time), Coast FIRE (enough invested early that growth alone reaches the number by a later age), Barista FIRE (partial retirement with part-time work).

05

The safe withdrawal rate isn't a withdrawal rate — it's a starting rate, then adjusted for inflation each year. Pulling out 4% literally each year (not inflation-adjusted) is different and more aggressive.

06

The 4% rule's research is stock-heavy: Bengen recommended holding 50-75% stocks; Trinity tested five mixes from 100% stocks to 100% bonds. At 4% inflation-adjusted over 30 years, Trinity's 25/75 bond-heavy mix succeeded only 71% of the time.

07

Sequence-of-returns risk: Bengen's worst US starts, 1966 and 1969, met the 1973-74 bear market and high inflation in their first decade. The same average return in a different order would have left far more.

08

Bengen kept revising his own rule: 4.5% in 2020 (his "SAFEMAX", worst case retiring October 1968), then 4.7% in late 2025 on a broader multi-asset portfolio. The 4% version is the floor his data supported, not his final word.

09

The FIRE philosophy is often traced to "Your Money or Your Life" (Vicki Robin & Joe Dominguez, 1992); blogs such as Mr. Money Mustache made it a movement in the 2010s.

10

Real return assumption matters more than nominal. The deep long-run datasets put US equities near 6.6% real (UBS Global Investment Returns Yearbook 2026, 1900-2025). Non-US-heavy portfolios deserve a more conservative test — run 5-6% and compare.

Frequently Asked Questions

  • It's the Schelling point — well-supported by US historical data, not bullet-proof. Bengen himself later published higher figures (4.5% in 2020, 4.7% in late 2025 on a broader portfolio); Morningstar's 2025 estimate is 3.9% for 30 years and 3.3% for 40. Use 4% as a 30-year reference point, a lower rate for a longer retirement, and expect to adjust spending in down years.

  • Everything you'll spend in retirement: housing, food, transport, healthcare, travel, hobbies, taxes, insurance. Exclude work-related costs (commute, work clothes, lunches) but add retirement-specific costs (more healthcare, more travel). A year of tracked spending is a better base than a budget, and any margin you add for safety goes straight into the number.

  • The deep long-run datasets put US equities around 6.6% real, inflation-adjusted (UBS Global Investment Returns Yearbook 2026, 1900-2025). A balanced stock-bond portfolio lands lower. Comparable multi-decade series for ASEAN markets are thin, so treat any regional figure with suspicion. Use 6-7% if mostly in US/global stocks; 5% for a balanced portfolio; 4% for conservative.

  • No — your home generates housing services, not investment income. The exception: if you plan to downsize and unlock equity in retirement, count the planned net proceeds as portfolio. For most users, exclude home equity entirely and budget retirement housing costs separately in annual expenses.

  • Treat them as expense reducers. If Social Security / CPF Life / your DB pension pays $X/year starting at age 65, subtract $X from your annual expenses for years 65+. Most FIRE practitioners do the math two ways: portfolio-only (conservative) and portfolio-plus-state-benefits (realistic).

  • Coast FIRE = the portfolio size where compounding alone (zero further contributions) gets you to full FIRE by traditional retirement age. It's the "one-and-done" milestone — you stop saving aggressively and let time do the work. See our Coast FIRE Calculator for the specific math.

  • The math works anywhere — but the variables differ. Salaries and expenses differ, healthcare works differently, and long-run return records for ASEAN markets are much shorter than the US one the 4% research rests on. Test a lower real return (5-6% instead of 7%) and a lower withdrawal rate: stopping work at 40 means a horizon longer than any of the studies above tested.

  • Build it into your annual expenses estimate. If you currently spend $40K but plan to travel more in retirement, model $55-60K. The SWR already adjusts for general inflation — what you need to add is the lifestyle adjustment specific to retired life (more leisure, more travel, more healthcare).

  • Three levers, in order of impact: (1) increase savings rate — the highest-leverage move; doubling savings rate roughly halves time to FIRE; (2) cut expenses — lowers both your savings target AND your annual outflow, double effect; (3) increase return — modest improvements compound dramatically over long horizons, but don't reach for risk to do it.

  • No. The calculation runs in your browser, and the figures you type are not sent to our servers or stored.

Method & sources

How it computes

FIRE number = annual spending ÷ safe withdrawal rate (4% by default, so 25× spending), exact in integer cents. Years to FIRE: each year the balance grows at the entered REAL return and the year's contribution is added at the year end; the answer is the first whole year it reaches the number, or "not within 100 years". The 4% default is Bengen's 1994 finding for 30-year US retirements, corroborated by Trinity 1998 (RecaInvest.fireNumber).

What this tool implements

  • The FIRE number is spending ÷ rate: 25× at 4%, 28.6× at 3.5%, 33.3× at 3%, computed in integer cents and basis points and rounded half-up.
  • Years to FIRE grow the balance at the real (after-inflation) return, then add that year's saving; a return of 0 is 0 and a blank field is refused, never replaced by a default.
  • The 4% default is a 30-year US finding (Bengen 1994: no 50/50 portfolio exhausted in under 33 years, 1926-1976 starts; Trinity 1998 Table 3: 95-98% at 50-100% stocks). Longer horizons are pointed lower: Bengen's 3% to about 3.5% lasted 50+ years; Morningstar 2025 gives 3.3% for 40 years.
  • Corrected 2026-10-19: a real return of 0 was read as the 7% default (and an SWR of 0 as 4%); unsourced claims removed (Big ERN 3.25-3.5%, healthcare at 2-3× inflation, the 1-3 year cash buffer, "zero outbound traffic", the claim that "Your Money or Your Life" never uses the acronym); the Mr. Money Mustache figure restated as his "about 16" with this tool's 17 years at 5% and 15 at 7%; a freshness stamp added.

Sources

What can make this go out of date

  • The 6.6% real-return hint is the UBS Yearbook 2026 figure; the Yearbook is republished each year.
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