FIRE Calculator
Find out when you can retire early. Calculate your FIRE number, time to financial independence, and compare Lean, Regular, Fat, Coast and Barista FIRE scenarios.
FIRE stands for Financial Independence, Retire Early. The movement crystallized in the 1990s around the book "Your Money or Your Life" and exploded after 2008 as knowledge workers realized a four-hour commute and a bad manager were optional purchases — if your portfolio could pay your bills, nobody could make you show up. The phrase misleads a little: the point is less about golf at 40 and more about opting out of forced work. Financial independence is the goal. Retiring is just one thing you can do with it.
The math is simpler than the lifestyle. If a diversified portfolio can sustainably fund your spending forever, you're financially independent. The Trinity Study (1998) gave that idea a number — withdraw 4% of a 50/50 stock/bond portfolio, inflation-adjusted, and historically it held up across 30-year retirements. Invert that 4% and you get 25: the multiplier from annual expenses to portfolio target. A household spending $60,000 a year needs about $1.5 million invested. Nothing more, nothing less.
This calculator runs that math across five FIRE flavors — Lean, Regular, Fat, Coast, and Barista — so you can see the target, the time to reach it, and the monthly savings required to hit 10-year acceleration. Change the withdrawal rate from 4% down to 3% if you want the Bengen-modern conservative view, or up to 5% if you're optimistic. The point isn't to hit one magic number; it's to see how the inputs interact.
How the FIRE numbers are calculated
The core equation is the safe withdrawal rate (SWR) multiplier. Your FIRE number equals annual retirement expenses divided by the SWR, expressed as a decimal. At 4%, dividing by 0.04 is the same as multiplying by 25. At 3.5% it is 28.6×. At 3% it is 33.3×. Lower withdrawal rates demand larger nest eggs because they assume longer horizons or worse starting valuations than the 1926-1995 window the Trinity Study sampled.
Time until FIRE comes from solving the future-value-of-annuity equation for t. Given a starting portfolio P, a monthly contribution PMT, a real annual return r, and a target T, the closed form is t = ln((T·r + 12·PMT) / (P·r + 12·PMT)) / ln(1 + r). Real means after inflation — that way the target in today’s dollars and the accumulation in today’s dollars match. If you plug in a nominal 10% return on stocks without subtracting 3% inflation, you will underestimate your FIRE date.
Coast FIRE is not a target; it's a checkpoint. It's the portfolio value where, if you stopped contributing today, compounding alone gets you to Regular FIRE by a chosen age. Mathematically, Coast = Regular / (1 + r)^years_remaining. Once you hit Coast, you can in theory switch to a job that covers expenses but doesn't save a cent, and still retire on schedule. Barista FIRE solves the same problem with different math: a part-time income chops your required withdrawal, shrinking the target proportionally.
FIRE = annual expenses × (100 / SWR%) · t = ln((T·r + 12·PMT)/(P·r + 12·PMT)) / ln(1+r)
- T
- Target FIRE number (portfolio value)
- P
- Current savings (portfolio today)
- PMT
- Monthly contribution
- r
- Real (after-inflation) annual return, decimal
- SWR
- Safe withdrawal rate, percent (4% = Trinity default)
Practical examples
30-year-old, $50k/year expenses, aggressive saver
Setup: Age 30, $50,000 saved, $50,000 annual expenses, $2,000/month contribution, 5% real return.
FIRE number = $50,000 × 25 = $1.25M. Starting with $50k, adding $24k/year that grows at 5% real, the closed form gives t ≈ 24.2 years. That's Regular FIRE at age 54. Lean FIRE (60% of expenses → $750k target) arrives around age 47. Coast FIRE today: about $374k — reach that, stop saving, and $1.25M is waiting at 65.
Takeaway: Aggressive-but-sustainable numbers put Regular FIRE in your mid-50s, not your 40s. The popular FIRE blog examples that claim retirement at 40 usually assume 8-10% real returns or unrealistic savings rates. Build a plan around 5% real and you'll be pleasantly surprised if markets outperform, not devastated if they don't.
Coast FIRE with a target age of 65
Setup: Age 35, $200,000 saved, $60,000 annual expenses, $0 additional contribution, 5% real return.
Regular FIRE = $60,000 × 25 = $1.5M. Years remaining to age 65: 30. Coast = $1.5M / (1.05)^30 ≈ $347,000. Your $200k portfolio is at 58% of Coast today. Five more years contributing $1,500/month closes the gap.
Takeaway: Coast FIRE is powerful psychologically: the intense-saving phase has a defined finish line. Once past Coast, you can take a lower-paying job with better work-life balance, launch a business, or take a sabbatical, and still retire on the original schedule.
Barista FIRE with a $20k part-time income
Setup: Age 40, $500,000 saved, $60,000 annual expenses, $15,000 part-time income, $1,500/month contribution, 5% real return.
Portfolio only has to fund $60k − $15k = $45k of expenses → $45,000 × 25 = $1,125,000 target. Starting with $500k plus $18k/year, time to Barista FIRE: about 14 years. Regular FIRE on the same inputs: 19+ years.
Takeaway: Part-time work isn't defeat — it's leverage. A $15k/year barista job or consulting gig shaves five years off your timeline and keeps you connected to the working world. Many people who plan Barista FIRE discover they enjoy the rhythm enough to keep doing it indefinitely.
Practical tips
- Model in real returns, not nominal. The calculator expects the real return (after inflation). Historical US equities have returned about 7% real, bonds 2% real, a 60/40 blend roughly 5% real. Use 4-5% for planning and 6%+ only if you are comfortable with the volatility required to capture it.
- Back out retirement expenses, not current expenses. Your FIRE spending probably differs from today: mortgage paid off, kids out of college, healthcare higher. Work through a line-by-line projection rather than assuming your current budget holds forever. Many Americans underestimate healthcare by $10k/year in early retirement before Medicare kicks in.
- The 4% rule assumes a 30-year horizon. If you retire at 40, you are planning for 50+ years. Academic consensus (Pfau, Kitces, Bengen himself) suggests 3.0-3.5% is more prudent over 50 years, especially at today's CAPE ratios. Drop the SWR and see how much harder the math gets — that gap is the honest price of extending your horizon.
- Your savings rate matters more than your return. The most cited FIRE chart (Mr. Money Mustache, 2012) shows that at a 10% savings rate you retire in 51 years; at 50% you retire in 17. Investment returns help, but savings rate is the lever you actually control.
Limits of this calculator
Doesn't model sequence-of-returns risk. If the market crashes in years 1-3 of retirement, a fixed 4% withdrawal rate is more dangerous than the average suggests. Monte Carlo simulators (FICalc, Portfolio Visualizer) run thousands of market histories; this calculator gives you the central estimate, not the tail risk.
Doesn't account for taxes on withdrawals. US retirees pulling from 401(k)/IRA pay ordinary income rates; Roth accounts are tax-free; brokerage sells trigger capital gains. In Brazil, rendimentos de renda fixa têm IR regressivo and the picture differs further. Add 10-25% buffer to cover the tax drag on your real spending.
Doesn't handle Social Security, pensions, or inheritance. These reduce how much portfolio you need; ignoring them makes you save more than strictly required. If you expect $1,500/month from Social Security at 67, that's equivalent to $18,000 less in annual expenses — or $450,000 less in FIRE number.
Doesn't include home equity as part of your portfolio. The home covers a housing expense, not a withdrawal. Counting it toward your FIRE number is the single most common mistake in FIRE blog comments; don't.
Frequently asked questions
Is the 4% rule still safe in today's market?▾
Depends on your horizon. For a 30-year retirement starting today, 4% is still defensible — Bengen himself published updated work in 2020 arguing 4.5-4.7% even holds for moderate-growth portfolios. For 50+ year retirements (early FIRE), most researchers now recommend 3.0-3.5% as a safer baseline, citing elevated CAPE ratios and the longer horizon's higher sequence-of-returns risk. Run the math both ways in the calculator to see the impact.
What's the difference between Lean FIRE and Fat FIRE?▾
Lean FIRE assumes austere spending — think $25-40k/year for a single person, often in a low-cost-of-living area, careful about housing and restaurants. Fat FIRE assumes a comfortable upper-middle-class lifestyle — $100k-150k+/year, nicer travel, bigger house, more healthcare buffer. Same math, different number. Lean retires earlier (smaller target); Fat requires a longer accumulation but more cushion for surprises. Regular FIRE is the middle path most people plan around.
How does Coast FIRE actually work?▾
Coast FIRE is the point where your portfolio is large enough that compound growth alone, with zero further contributions, reaches Regular FIRE by your chosen retirement age. Once you've hit Coast, you can switch to a lower-stress job that covers expenses but saves nothing, and you're still on track. It's especially powerful in your 30s: Coast FIRE at 35 with a 5% real return and target age 65 needs only about 23% of your Regular FIRE number, because 30 years of compounding does the rest of the work.
Should I count my home equity toward my FIRE number?▾
No. Your home covers a housing expense; it isn't a withdrawal-generating asset. Including it in the portfolio double-counts: you're already subtracting mortgage/taxes/maintenance from the expense side. The only cases where home equity matters to the plan: if you intend to downsize and invest the difference, or if you plan a reverse mortgage. Even then, treat those as options, not as portfolio.
What about healthcare costs in early retirement?▾
This is the biggest blind spot in US FIRE planning. ACA subsidies make coverage affordable if your reported income is low — typically $500-900/month for a family at moderate incomes. Add a $5-10k deductible and it climbs. Plan to add $10,000-15,000/year to your expense line between retirement and Medicare eligibility at 65. Brazilian planejadores have it easier (SUS exists) but many FIRE candidates still budget for a private plano de saúde — at 50+ years old, that can run R$2,000-4,000/month.
Is FIRE realistic for someone earning average income?▾
Aggressive FIRE (retire at 35-45) typically requires either high income or extreme frugality — usually both. Regular FIRE at 50-55 is reachable on average US household income (~$75k) with a 25% savings rate. The honest answer: the later you start and the lower your savings rate, the more FIRE becomes 'Financial Independence, Retire at a Normal Age' — which is still transformative. Don't let purist FIRE blogs convince you it's worthless if you can't hit 40.
Sources
Related calculators
Compound Interest
Calculate compound interest with monthly contributions. See how your money grows over time.
Mortgage
Calculate monthly mortgage payment, total interest, and amortization schedule. Compare Price vs. SAC systems.
Tip
Calculate tip amount, total bill, and per-person split — with smart rounding and regional tipping guidance.
Loan Calculator
Monthly payment, total interest and amortization schedule for personal, auto, or consumer loans.