FIRE Calculator
Calculate your Financial Independence number, years to retirement, and whether you're on track to retire early.
Coast FIRE is the amount you need today that will grow to your FIRE number by traditional retirement age (65), without any additional contributions.
| Year | Age | Portfolio | Progress | Status |
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Frequently Asked Questions about FIRE
Your FIRE number is the total investment portfolio size needed to cover your living expenses indefinitely without working.
Formula: FIRE Number = Annual Expenses ÷ Safe Withdrawal Rate
Using the common 4% rule: FIRE Number = Annual Expenses × 25. If you spend $60,000/year → FIRE number = $1,500,000.
The lower your annual spending, the smaller your FIRE number — and the sooner you can achieve financial independence.
The 4% rule (Bengen, 1994) states that withdrawing 4% of your portfolio in year 1, then adjusting for inflation annually, results in a portfolio lasting at least 30 years across most historical US market scenarios.
The "Trinity Study" further validated this across different asset allocations. However, for early retirees with 40–50 year horizons, many FIRE practitioners use a more conservative 3% or 3.5% withdrawal rate to account for sequence-of-returns risk and longer time horizons.
This calculator defaults to 4% but you can adjust it in Advanced Settings.
Coast FIRE is the amount you need invested right now so that it will grow to your full FIRE number by age 65, without any additional contributions.
Formula: Coast FIRE = FIRE Number ÷ (1 + return)^years to 65
Once you hit Coast FIRE, you can "coast" — you only need to earn enough to cover current expenses, not save for retirement. This is a popular intermediate milestone for those who can't yet achieve full FIRE.
Lean FIRE — retire on a minimal budget (<$40K/year). Requires extreme frugality. FIRE number ~$1M.
Fat FIRE — retire with a comfortable lifestyle ($100K+/year). More financial cushion. FIRE number $2.5M+.
Barista FIRE — semi-retire: work part-time (e.g., barista) to cover basic expenses while your portfolio covers the rest. Lets you retire earlier with a smaller portfolio and keep health benefits.
Coast FIRE — have enough invested now that it will grow to your full FIRE number without additional contributions.
Your savings rate is the most powerful lever. It both grows your portfolio faster and reduces your FIRE number (lower spending = smaller target).
10% savings rate → ~40 years to retire | 25% → ~32 years | 50% → ~17 years | 65% → ~10.5 years | 75% → ~7 years
Use the calculator above to model your specific situation. Reducing annual spending by $10,000 cuts your FIRE number by $250,000 (using the 4% rule).
How FIRE Works — The Shockingly Simple Math
FIRE stands for Financial Independence, Retire Early. The movement traces its popular origin to Jacob Lund Fisker's 2010 book Early Retirement Extreme and Mr. Money Mustache's 2012 essay "The Shockingly Simple Math Behind Early Retirement," which showed that the years-to-retirement calculation depends almost entirely on one variable: your savings rate.
The reason is structural. A high savings rate does two things at once: (1) it increases the amount of money you're adding to the portfolio each year, and (2) it means your spending is low, which reduces your target FIRE number (which is 25× annual spending). Those two effects multiply. Save 10% and you're looking at roughly 51 years to retirement at 5% real returns. Save 60% and it's about 12.5 years. Save 75% and it's about 7 years. Income barely matters — only the ratio of saved to spent.
The FIRE community borrowed its withdrawal-rate math from William Bengen's 1994 Journal of Financial Planning paper, which found that 4% of starting portfolio (adjusted for inflation annually) survived every 30-year rolling period in US market history. The 1998 Trinity Study by Cooley, Hubbard and Walz extended this across asset mixes. Multiply annual spending by 25 and you get the same target — this is the 25× rule, which is algebraically identical to the 4% rule.
The Core FIRE Formulas
SWR— Safe Withdrawal Rate (4% is the Bengen / Trinity baseline; 3.5% for 40-year horizons)Annual Spending— your target post-retirement annual expenses in today's dollars- 25× shortcut: because 1/0.04 = 25, spend × 25 = FIRE number
r— real (inflation-adjusted) annual return (commonly 5–7%)t— years until traditional retirement age (usually 65 − current age)- Coast FIRE is the amount you need now that will grow to full FIRE by age 65 with zero additional contributions
- The single most important FIRE number — the direct lever on years-to-retirement
- Use take-home numbers (post-tax) for consistency with the spending side
The Savings-Rate → Years-to-FIRE Table
This is the canonical Networthify / Mr. Money Mustache table — years to FIRE based purely on your savings rate, assuming a 5% real return and a 4% withdrawal rate, starting from zero:
| Savings Rate | Years to FIRE | What It Feels Like |
|---|---|---|
| 10% | ~51 years | Traditional retirement; Social Security required |
| 15% | ~43 years | Standard retirement guidance (15% rule) |
| 20% | ~37 years | Above average; retire in late 50s |
| 25% | ~32 years | Solid; retire at 57 |
| 30% | ~28 years | Ambitious; retire in early 50s |
| 40% | ~22 years | Aggressive; retire in mid-40s |
| 50% | ~17 years | Classic FIRE — the Mustachian baseline |
| 60% | ~12.5 years | Hardcore; retire ~42 if start at 30 |
| 65% | ~10.5 years | One career-change worth |
| 75% | ~7 years | Extreme FIRE; fastest realistic path |
Worked Example — Elena, 30, $80K Income
FIRE Variants — Pick Your Flavor
| Variant | Typical Annual Spending | Target Portfolio | Description |
|---|---|---|---|
| Lean FIRE | <$40,000 | ~$1.0M | Frugal lifestyle; often geo-arbitrage to low-cost-of-living areas |
| Regular FIRE | $40–80K | $1–2M | Middle-class retirement; the default FIRE case |
| Fat FIRE | $100K+ | $2.5M+ | Comfortable / luxurious; travel, dining, private school |
| Barista FIRE | Varies | Partial | Semi-retire; part-time work covers some expenses and health benefits |
| Coast FIRE | N/A | ~$200–400K early | Invest enough now; let compounding finish the job by age 65 |
FIRE Rules of Thumb
A $200K earner saving 10% ($20K/yr) retires much later than a $50K earner saving 60% ($30K/yr). The ratio of saved to spent drives the math. Lifestyle inflation destroys FIRE.
Bengen's 4% rule was designed for 30 years. For a retirement starting at 40 that might run 50+ years, reduce to 3.5% or 3.25% to give a safety buffer against sequence-of-returns risk — the biggest threat to an early retiree.
Use 5–7% real returns in projections (not 10% nominal), and express spending in today's dollars. Mixing nominal returns with real spending silently inflates your plan.
How to Use This Calculator
- Enter your current age and target FIRE age. The difference is your contribution horizon.
- Enter current savings/investments — total of brokerage, IRA, 401(k), HSA, Roth. Exclude your primary home unless you plan to sell.
- Enter annual savings contribution — employer match counts. Aim for a 30–50% savings rate for traditional FIRE.
- Enter annual spending in retirement in today's dollars. This drives your FIRE number via the 25× rule.
- Check Advanced Settings for expected return (default 7%), safe withdrawal rate (default 4%), and inflation (default 3%). Adjust conservatively.
- Read years-to-FIRE and Coast FIRE. Try raising your savings rate by 5% and watch the timeline shrink.
Methodology & Assumptions
- Expected return: 7% nominal (≈5% real after 3% inflation) — based on long-run S&P 500 total return (Damodaran, Shiller).
- Inflation: 3% long-run average (BLS CPI-U 1928–2025).
- Safe Withdrawal Rate: 4% — Bengen 1994 / Trinity Study 1998 baseline for 30-year retirements.
- Portfolio projections assume constant returns; actual markets are volatile and sequence-of-returns risk is not modeled.
- FIRE number = Annual Spending × 25 (equivalent to Spending ÷ 4% SWR).
- Coast FIRE uses Coast = FIRE Number ÷ (1 + return)^(65 − age).
- Social Security income is not included by default — a conservative choice.
- All math runs locally in your browser.
Glossary
- FIRE
- Financial Independence, Retire Early. Portfolio large enough that investment returns cover spending indefinitely.
- FIRE number
- Target portfolio size. FIRE number = Annual Spending × 25 (using the 4% safe withdrawal rate).
- Safe Withdrawal Rate (SWR)
- The percentage of your starting portfolio you can withdraw annually (adjusted for inflation) without running out. 4% is baseline; 3.5% is conservative for long horizons.
- 4% rule / 25× rule
- Bengen's 1994 finding that 4% of starting portfolio (inflation-adjusted annually) survives every historical 30-year period. 25× is its algebraic twin.
- Trinity Study
- 1998 extension by Cooley, Hubbard and Walz, testing Bengen's 4% rule across different asset allocations. Confirmed 4% for 30 years.
- Coast FIRE
- Amount you need invested today that will grow to full FIRE by age 65 without additional contributions. An intermediate milestone.
- Lean FIRE
- Early retirement on a frugal budget — typically under $40,000/year in spending.
- Fat FIRE
- Early retirement on a comfortable budget — typically $100,000+/year in spending.
- Barista FIRE
- Semi-retirement: part-time job (e.g., at a coffee shop) covers basic expenses and health benefits while the portfolio covers the rest.
- Chubby FIRE
- Middle ground between Regular and Fat FIRE, roughly $80–150K/year spending.
- Sequence-of-returns risk
- The danger that poor market returns early in retirement permanently damage your withdrawal sustainability, even if average long-run returns are fine.
- Savings rate
- Saved / (Saved + Spent), using post-tax income. The single most powerful FIRE lever.
Frequently Asked Questions
FIRE Number = Annual Spending × 25 (equivalent to Spending ÷ 4% SWR). Spend $60,000/year → $1,500,000 FIRE number. Lower spending compounds in two directions — you save more each year and the 25× target shrinks.
From Bengen's 1994 Journal of Financial Planning paper: withdrawing 4% in year 1 and inflation-adjusting annually survived every rolling 30-year US history period. The 1998 Trinity Study confirmed across asset allocations. For FIRE's 40–50 year horizons, many planners use 3.5% or 3.25% for extra safety against sequence-of-returns risk.
From MMM's "Shockingly Simple Math": 10% → ~51 yrs, 25% → ~32 yrs, 50% → ~17 yrs, 60% → ~12.5 yrs, 65% → ~10.5 yrs, 75% → ~7 yrs. Savings rate is THE lever — income barely matters, only the ratio saved to spent.
The amount invested today that will grow to full FIRE by age 65 with zero future contributions. Formula: Coast FIRE = FIRE Number / (1 + r)^(65 − age). Reaching Coast lets you stop saving and only earn enough to cover current expenses — retirement is already funded by compounding.
Lean: <$40K/yr spending, ~$1M target. Fat: $100K+/yr, $2.5M+ target. Barista: part-time work covers some expenses and health benefits — smaller required portfolio. Coast: stop saving now; compound growth finishes by 65.
Most FIRE planners use 7% real (or 10% nominal minus ~3% inflation), based on long-run S&P 500 total return. 60/40 portfolios use closer to 5% real. This calculator defaults to 7% nominal in Advanced Settings — edit if your allocation is more conservative.
4% is the 30-year baseline (Bengen/Trinity). For 40–50 year early retirement, 3.5% is a common compromise and 3.25% is the most conservative common choice. Morningstar's 2023 update suggested ~3.8% as a starting point. Lower = smaller safe spending but more margin against bad sequences.
For high earners with 50%+ savings rates, FIRE in 15–17 years is realistic and documented. Median earners usually target Lean FIRE or Coast FIRE. Big risks: healthcare costs, sequence-of-returns risk, divorce, disability. FIRE is math plus behavior — both must hold for decades.
SS replaces ~35–40% of pre-retirement income at full retirement age (67). If collecting SS at 67, your portfolio only needs to cover 100% of spending until 67, then ~60–65% after. This can lower the FIRE number materially. Use SSA Quick Calculator to estimate. Most FIRE calculators ignore SS for conservatism.
No — the FIRE number is the investment portfolio that generates income. Your home doesn't produce withdrawable cash. However, a paid-off home reduces your spending by the mortgage payment, which drops your FIRE number proportionally. Many planners track two figures: investment FIRE number and total net worth including home equity.