The FIRE Movement: Financial Independence, Retire Early
FIRE means building investments large enough that withdrawals can cover your living costs for the rest of your life. The goal is not necessarily to stop working, but to make paid work optional. This FIRE calculator estimates when your portfolio reaches that point based on what you earn, what you spend, and what your investments return.
The Math Behind FIRE: The 4% Rule
Your FIRE number is your annual spending divided by a safe withdrawal rate. At 4%, that is 25× annual expenses: $40,000 a year of spending needs $1,000,000.
The 4% figure comes from financial planner William Bengen's 1994 study, which found that an initial 4% withdrawal, increased each year for inflation, lasted at least 30 years in every historical US period he tested. The 1998 "Trinity study" by three Trinity University professors reached similar conclusions: with a 75% stock / 25% bond portfolio, a 4% inflation-adjusted withdrawal survived about 98% of historical 30-year periods.
Early retirees need their money to last 40–60 years, so many use a more cautious 3.25–3.5% rate (a FIRE number of roughly 29–31× expenses), or plan to cut spending after bad market years.
Lean, Regular and Fat FIRE
- Lean FIRE (roughly $25,000–$40,000/year): a frugal lifestyle; FIRE number about $625,000–$1,000,000 at 4%.
- Regular FIRE (roughly $40,000–$80,000/year): FIRE number about $1–2 million.
- Fat FIRE ($100,000+/year): $2.5 million or more.
- Coast FIRE: you have saved enough that, with no further contributions, growth alone should reach your FIRE number by a traditional retirement age — so you only need to earn your current expenses.
- Barista FIRE: a portfolio covers part of your spending and part-time work covers the rest.
How Savings Rate Determines Your Retirement Date
When you start from zero, the time to financial independence depends almost entirely on your savings rate, not your income: a high savings rate both builds the portfolio faster and lowers the amount you need. The table below uses the calculator's method (5% real return, 4% withdrawal rate, monthly investing, starting from $0) — the same approach popularized by the blogger Mr. Money Mustache's "shockingly simple math" post.
| Savings Rate | Years to FI | FI Age if You Start at 25 |
|---|---|---|
| 5% | 64.3 years | 89 |
| 10% | 50.2 years | 75 |
| 15% | 41.9 years | 66 |
| 20% | 35.9 years | 60 |
| 25% | 31.2 years | 56 |
| 30% | 27.4 years | 52 |
| 40% | 21.2 years | 46 |
| 50% | 16.3 years | 41 |
| 60% | 12.2 years | 37 |
| 65% | 10.3 years | 35 |
| 70% | 8.7 years | 33 |
| 75% | 7.0 years | 32 |
A person earning $50,000 who saves 50% (living on $25,000) and a person earning $200,000 who saves 50% (living on $100,000) reach financial independence at about the same time, because the higher earner also needs a four-times-larger portfolio.
How to Work Toward FIRE
- Know your number: track real spending for several months, then multiply annual expenses by 25 (or ~29–31 for a longer, more cautious plan).
- Raise the gap between income and spending: housing, transportation and food are usually the largest levers; income growth matters as much as cutting costs.
- Invest in low-cost, diversified funds and use tax-advantaged accounts (401(k), IRA, HSA) before taxable ones.
- Plan access to retirement money before 59½: taxable accounts, Roth contribution withdrawals, Roth conversion ladders, the 401(k) "rule of 55" and 72(t) payments are common approaches.
- Re-check yearly and adjust savings or the target as life changes.
Common FIRE Mistakes
- Underestimating expenses: irregular costs (car replacement, home repairs, travel) are easy to miss.
- Forgetting health insurance: before Medicare at 65, marketplace premiums depend on age, location and income-based subsidies and can be a major budget line for early retirees.
- Using a 4% rate for a 50-year retirement without any flexibility to cut spending in bad years.
- Sequence-of-returns risk: a large market drop in the first years of retirement does more damage than the same drop later.
- Mixing nominal and real numbers: if your target is in today's dollars, use an after-inflation return (as this calculator does by default).