Most people guess at it. Finance nerds have calculated it to the dollar.
This is your number — broken down by your age, your lifestyle, and how fast you're willing to get there.
The One Rule That Decides Everything
In 1998, researchers at Trinity University published a study that became the foundation of the entire early-retirement movement. Their finding: if you withdraw 4% of your investment portfolio per year (adjusted for inflation), your money survives 30 years with 95%+ success, based on historical U.S. market data.
That gives you the magic formula:
Your number = Annual spending × 25
Spend $40,000 a year? You need $1 million. Spend $60,000? You need $1.5 million. It's that simple — and that powerful.
One caveat: if you retire at 40, you're not planning a 30-year retirement — you're planning a 50-year one. Many early-retirement researchers argue for a more conservative 3.25%–3.5% withdrawal rate for very long retirements, which pushes your multiple to about 28–31× your spending.
Your Number by Lifestyle Tier
The movement has three named flavors. Pick yours:
| Lifestyle | Annual spending | FIRE number (4% rule) | FIRE number (3.5% conservative) |
|---|---|---|---|
| Lean (frugal, minimal) | $35,000 | $875,000 | $1,000,000 |
| Regular (comfortable, typical) | $60,000 | $1,500,000 | $1,714,000 |
| Fat (affluent, no compromises) | $120,000 | $3,000,000 | $3,429,000 |
Real-world data backs up these buckets: community guides consistently describe Lean FIRE as $500K–$1M portfolios supporting $20–30K/year, and Fat FIRE as $2.5M+ supporting $100K+/year.
Your Number by Age
Here's where it gets personal. Your required number doesn't change much with age — but how fast you must reach it absolutely does.
If you're 25
You have time. You don't need a fortune today — you need a high savings rate.
| Savings rate | Years to financial independence | Done by age |
|---|---|---|
| 10% | ~51 years | 76 |
| 25% | ~32 years | 57 |
| 50% | ~17 years | 42 |
| 70% | ~8.5 years | 34 |
| 75% | ~7 years | 32 |
(Based on standard FIRE math at ~5–7% real returns. Verified against multiple FIRE calculators.)
If you're 35
A 50% savings rate now has you free at 52. At 25% you're at 67 — normal retirement age.
If you're 45
Time is short, so the rate has to be high. Saving 70% from 45 has you independent by about 54. At 25%, you're looking at 77.
If you're 55
You're not "retiring early" — you're retiring well. If you have half your target saved, the finish line is much closer than you think: at 7% returns, money doubles roughly every 10 years even without new contributions.
What Actually Moves the Needle
Your savings rate dwarfs everything else. A raise doesn't change your timeline as much as a 5-point bump in savings rate. The difference between saving 30% and 50% isn't 20 points — it's the difference between working 28 more years and 17.
Three accelerators nobody talks about enough:
- Geo-arbitrage. Retiring in a low-cost state (or country) can shrink your number 20–30%. A $60,000 lifestyle in Arkansas costs far less than in California — and your number drops with it.
- Flexibility. Planning to spend a little less in down-market years dramatically improves the math. This is why flexible retirees can safely use higher withdrawal rates.
- Part-time income. Covering just $15,000/year of expenses in early retirement cuts your required number by roughly $375,000.
The Bottom Line
Your "never work again" number isn't a fantasy. It's your annual spending times 25 — and your timeline is almost entirely a function of your savings rate. Pick your tier, pick your rate, and the rest is arithmetic.
FAQ
Is the 4% rule still valid?
Yes, as a baseline. The Trinity Study's 4% rule has survived decades of scrutiny for 30-year retirements. For retirements lasting 40–50 years, many planners recommend 3.25%–3.5% instead.
Does the number include Social Security?
The ×25 rule is a rough total-portfolio target. If you expect Social Security income, subtract it from your annual spending before multiplying.
What about inflation?
The 4% rule already accounts for inflation — you increase withdrawals each year to match rising prices. All numbers here are in today's dollars.
Do taxes change the math?
Yes. Your number covers pre-tax spending. In retirement you'll owe taxes on most withdrawals, so your true number is a bit higher. Roth accounts soften this.
Is $1 million still enough to retire?
$1 million supports about $40,000/year at the 4% rule — before taxes and Social Security. It's enough for a lean retirement in a low-cost area, but not a comfortable one in an expensive city.
Tool tie-in: An interactive "FIRE date calculator" (age + savings + savings rate → your quit date) would sit perfectly after the age section.