The FIRE number is the target that makes financial independence math concrete. Without it, "retire early" is a vague aspiration; with it, you have a specific portfolio size to build toward. The core formula is simple, but the important adjustments are what separate retirees who thrive from those who run out. Here is the complete picture for 2026.
What changed in 2026
- The 4% rule debate intensified. With bond yields normalizing and equity valuations elevated, some researchers argue for a 3.3–3.5% withdrawal rate for 50-year retirements. The 4% rule still holds as a reasonable starting point, but longer-horizon retirees should stress-test it.
- Healthcare costs remained the largest FIRE wild card — ACA marketplace premiums and out-of-pocket costs continue to be difficult to project, and pre-Medicare retirees must model them explicitly.
- Part-time income changed the math. "Coast FIRE," "Barista FIRE," and hybrid approaches — where a small amount of income supplements withdrawals — are now standard variations, not edge cases.
- Tax planning matters more. Roth conversion ladders, LTCG harvesting, and ACA subsidy optimization are now well-documented FIRE tools, but require careful execution.
The base formula
Annual expenses × 25 = FIRE number
This derives from the 4% safe withdrawal rate: if you withdraw 4% of your portfolio annually, the portfolio should — based on historical data — last 30+ years.
| Annual expenses |
FIRE number (25x) |
3.5% FIRE number (28.6x) |
| $30,000 |
$750,000 |
$857,000 |
| $40,000 |
$1,000,000 |
$1,145,000 |
| $50,000 |
$1,250,000 |
$1,430,000 |
| $60,000 |
$1,500,000 |
$1,714,000 |
| $80,000 |
$2,000,000 |
$2,285,000 |
The 25x column is the standard. The 28.6x column is the more conservative number for those planning a 50-year retirement.
How to find your annual expenses
Use 12 months of actual spending data, then adjust:
- Start with your real average monthly spend (use a money audit or 12 months of statements)
- Remove work-related costs (commuting, work wardrobe, professional development)
- Add healthcare costs — if your employer currently covers insurance, you need to buy it yourself pre-Medicare
- Add one-time costs you are currently delaying (home repairs, vehicle replacement)
- Adjust for planned changes (paid-off mortgage, kids finishing school)
Healthcare is often $500–$1,500/month per person in the individual market depending on plan and income, and can vary significantly with ACA subsidy eligibility.
Adjusting for your specific scenario
| Scenario |
Adjustment |
| Retiring at 40–50 (50-year horizon) |
Use 3.5% rate (28.6x expenses) |
| Plan to do any paid work in retirement |
Can use 3.5–4.5% depending on amount |
| Have a pension or Social Security at 67 |
Reduce FIRE number by (annual benefit / 0.04) |
| Low expenses, flexible spending |
4% is more defensible |
| Large fixed expenses (healthcare, housing) |
Be conservative; use 3.5% or lower |
Accounting for Social Security
If you expect Social Security, subtract the annual benefit from your expense target before multiplying by 25.
Example: You need $50,000/year. You expect $18,000/year in Social Security at 67.
- Gap to cover from portfolio: $50,000 − $18,000 = $32,000
- FIRE number: $32,000 × 25 = $800,000
This is significantly lower than $1.25M — Social Security materially changes the target.
Sequence-of-returns risk
The 4% rule can fail even when long-run averages work out, if returns are negative in the first 5–10 years of retirement. You withdraw at bad prices, sell more shares, and never recover even when the market does.
Mitigations:
- 2 years of expenses in cash or short-term bonds (a buffer that does not require selling equities in a down year)
- Flexible withdrawals — cut discretionary spending in down years
- Part-time income even $500–$1,000/month reduces early portfolio draws dramatically
- Delay Social Security to maximize the guaranteed income floor
How to pick your number
- Calculate 12 months of real expenses
- Add healthcare cost estimate
- Subtract expected passive income (Social Security, rental, pension)
- Multiply the remaining gap by 25 (standard) or 28.6 (conservative / early retiree)
- Add a 10–15% buffer for unexpected costs
Common mistakes
Using income instead of expenses. Your FIRE number is based on what you spend, not what you earn. Reducing expenses reduces the target faster than increasing income.
Ignoring healthcare. Pre-Medicare health costs are the single most common FIRE plan killer. Model them explicitly.
Treating 4% as a guarantee. It is a historical estimate. Use it as a starting point, then stress-test with a 3.3% or 3.5% rate.
Forgetting taxes in retirement. Withdrawals from traditional 401k and IRA accounts are taxable income. Roth accounts are not. Your asset location matters.
Not adjusting for a 50-year horizon. The Trinity Study modeled 30 years. A 40-year-old FIRE retiree needs a more conservative number.
What to skip
- Overly complex FIRE calculators that require 30 inputs before giving an estimate — the 25x rule and a healthcare buffer get you to 90% accuracy.
- Locking in a rigid FIRE date before stress-testing with sequence-of-returns scenarios.
- All-equity portfolios at retirement even for FIRE believers — some cash/bond buffer meaningfully improves outcomes.
FAQ
Is 4% still the right withdrawal rate?
For 30-year retirements with average valuations, it is historically defensible. For 50-year early retirements, 3.3–3.5% is more conservative and appropriate.
What if my expenses will change in retirement?
Model it in phases. Many retirees spend more in early active years and less in later years. Healthcare is the exception — it typically increases.
Does the 4% rule work globally?
The original research used U.S. market data. International markets have had lower safe withdrawal rates historically. U.S. investors benefit from U.S. market performance.
How do I handle a mortgage in the FIRE number?
If the mortgage will be paid off before or at retirement, exclude it from post-retirement expenses. If not, include the payment in annual expenses.
Where to go next
See How to catch up on retirement savings in 2026, How to rebalance with new money in 2026, and How to set financial goals in 2026.