How this calculator works
FI number = annual spending ÷ withdrawal rate (4% default → spending × 25). The calculator then simulates monthly portfolio growth with your contributions until it crosses the target.
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FIRE Calculator — Your Financial Independence Number & Date
Financial Independence means your investments cover your spending forever. Enter your annual spending, current portfolio, monthly savings and expected return to get your FI number and date.
Scenario examples (2026 rates)
| Annual spending ($) | FI number (4% rule) | Years to FI |
|---|---|---|
| 20,000 | $500,000 | 8.1 |
| 30,000 | $750,000 | 11.5 |
| 40,000 | $1,000,000 | 14.3 |
| 60,000 | $1,500,000 | 18.6 |
| 80,000 | $2,000,000 | 21.9 |
Every number above is computed by the same in-browser engine as the calculator — nothing is hardcoded.
Why the FI number is spending times 25
The 25 multiplier is the reciprocal of a 4 percent withdrawal rate: spending divided by 0.04 equals spending times 25. The 4 percent figure traces to the Trinity study and its successors, which tested portfolios across rolling 30-year windows of US market history and found that withdrawing 4 percent of the initial balance in year one, then inflating that amount annually, left money intact in nearly all historical sequences for 50/50 to 100 percent stock portfolios. Spending $40,000 per year therefore implies a $1 million target. Two caveats belong in any honest reading. The studies cover 30-year retirements, while someone quitting at 40 faces 50 or more years, which is why early retirees often model 3.25 to 3.5 percent, raising the multiple to 29 or 31 times spending, an adjustment available in the withdrawal-rate field. And the inflation adjustment is the aggressive part: pulling a constant real income forces asset sales in down markets, which is the sequence risk that breaks rigid plans. Flexibility, trimming withdrawals 5 to 10 percent after bad market years, supports rates half a point higher.
What actually determines your FI date
Savings rate dominates every other variable, and the math shows why. Starting from zero at a 7 percent return, saving 10 percent of income reaches 25 times annual spending in roughly 51 years; 25 percent takes about 32 years; 50 percent about 17; 65 percent under 10. The pattern exists because the target scales with your spending while the accumulation scales with income minus that spending: cutting expenses shrinks the finish line and grows the contribution simultaneously, a double effect no raise or return tweak can match. Returns matter at the margin, a one-point higher return shaves perhaps two to four years off a 30-year plan, but they are not under your control. Current portfolio matters less than rate over long horizons: $100,000 already invested at 7 percent grows to about $761,000 in 30 years, yet a household saving 50 percent covers that gap from contributions in under two decades anyway. If you want the date to move, move the rate first and treat return assumptions as weather.
Stress-testing the plan before you commit
The calculator returns one date from one set of assumptions; a quitting decision needs the distribution around it. Re-run the same plan four ways. Lower returns: drop the expected return from 7 to 5 percent and see how far the date slips, typically five to eight years. Higher spending: add 15 percent to annual spending for the costs early retirees underestimate, health premiums before 65, home maintenance, and the spending bump free time creates. Lower withdrawal rate: set 3.5 percent instead of 4 and watch the target grow by about 14 percent, the honest setting for a 45-plus-year retirement. Inflation shock: if spending rises faster than expected, the real withdrawal rate climbs even with a flat dollar plan. A robust result is one where the FI date survives all four adjustments inside a few years, with a bridge fund in taxable assets and two to three years of expenses in cash at the quit date. A plan that only works at 7 percent returns, 4 percent withdrawals, and unchanged spending is a forecast, not a plan.
FAQ
Is 4% safe?
Historically yes for 30+ year US portfolios (Trinity study). For early retirement (50+ years), consider 3.25–3.5% — change the withdrawal rate field.
What's a good savings rate?
Saving 25% of income → FI in ~32 years; 50% → ~17 years; 65% → ~10 years. Your rate matters more than your income.
LeanFIRE vs FatFIRE?
LeanFIRE = minimal-spending FI (~$25–40k/yr); FatFIRE = comfortable FI ($100k+/yr → $2.5M+ portfolio). Same math, different spending input.
How do I account for the years before Medicare and Social Security?
Early retirees face a coverage bridge that standard FIRE math ignores. Health insurance before 65 costs a family roughly $12,000 to $20,000 per year on ACA marketplace plans before subsidies, and subsidies themselves depend on reported income, so many early retirees manage taxable income to stay eligible. Access to retirement money adds constraints: 401k balances are generally locked until 59 and a half unless you separate from service at 55 or older under the rule of 55, or run a substantially equal periodic payment, 72(t), schedule; Roth IRA contributions, but not earnings, come out any time tax-free; taxable brokerage has no age rules at all. The practical fix is a bridge fund: one to two years of expenses per gap year held in taxable or Roth contribution basis, sized before you quit. Add expected health insurance premiums to your annual spending input here; an FI number built on $40,000 of spending that omits $15,000 of insurance understates the target by nearly $400,000 at a 4 percent withdrawal rate.
What is Coast FIRE and how does it change the target?
Coast FIRE means your existing portfolio, left untouched, will grow to a full retirement number by 65 without further contributions, so you only need to earn enough going forward to cover current living costs. The math is simple discounting: at 7 percent, money doubles about every 10.2 years, so a 30-year-old holding roughly $130,000 in index funds is coasting toward about $1 million at 65, since it doubles close to three times. A 40-year-old needs roughly $250,000 for the same endpoint. Coast FIRE does not fund early spending, it funds the retirement account portion, so you still need a separate pot or cash flow for the years between quitting traditional saving and age 65. Model both pieces: run this calculator for the bridge, then check the coast figure with the compound interest calculator at your expected return and zero contributions. Many people discover they reached Coast years ago and keep over-saving out of habit.
Do 2026 contribution limits speed up the FI date?
Meaningfully, if you use them. The 2026 401k employee limit is $24,500, or $32,500 with the age-50 catch-up, and the IRA limit is $8,000, or $9,150 with catch-up. A couple both maxing 401ks shelters $49,000 to $65,000 per year from taxes while investing it. At a 7 percent return, an extra $20,000 invested annually pulls the FI date forward by roughly three to five years for a mid-accumulation household, depending on the gap to target. The tax layer matters for FIRE specifically: withdrawals in the low-income early-retirement years can be managed into the 0 percent long-term capital gains bracket, which for 2026 joint filers covers roughly the first $96,000 of taxable income, and Roth conversions in those low-income years are cheap. Enter your true annual savings in this calculator, including employer match, which typically adds 3 to 6 percent of salary on top of your contributions; omitting the match understates your rate and pushes the projected FI date years later than reality.