FIRE Number Calculator

Your FIRE number is the total portfolio value needed to retire and live off investment returns indefinitely. The classic formula is: FIRE Number = Annual Spending ÷ Withdrawal Rate. At the 4% rule, that's 25× your annual spending. Spend $60,000/year? You need $1,500,000. This calculator personalizes it further — accounting for Social Security income, part-time earnings (BaristaFIRE), healthcare costs, and your expected return rate.

CoastFIRE is the point where your current savings will compound to your full FIRE number by your target retirement age — even without any new contributions. Once you hit your CoastFIRE number, you've "won" in the sense that you only need to cover current expenses; the portfolio grows to full FIRE on its own. This calculator shows your exact CoastFIRE year and the savings level required.

The 4% rule was first established by financial planner William Bengen in his landmark 1994 paper and later validated by the 1998 Trinity Study (Cooley, Hubbard & Walz). The research found that a 4% annual withdrawal survived 95%+ of all historical 30-year periods for a 50/50 stock/bond portfolio. For early retirees with 40–50 year horizons, researchers suggest 3–3.5% is safer. This calculator runs 1,000 Monte Carlo simulations using historical return variance to show your specific success rate — giving you a more personalized answer than a single rule of thumb.

LeanFIRE targets retirement on a minimal budget (roughly 60% of current spending) — the fastest path but requires frugal living. Regular FIRE maintains your current lifestyle. FatFIRE targets an upgraded retirement with roughly 160% of current spending — more travel, dining, and flexibility. BaristaFIRE is semi-retirement: you retire with a smaller portfolio and supplement with $10,000–$30,000/year of part-time or passion work, often achievable 3–5 years before full FIRE. CoastFIRE is a milestone rather than a lifestyle — it's when you can stop investing and let compounding do the rest.

Social Security benefits reduce the income your portfolio needs to generate. If you'll receive $2,000/month ($24,000/year) in Social Security, that's $24,000/year you don't need to withdraw from your portfolio. At a 4% withdrawal rate, $24,000/year reduces your required portfolio by $600,000. This calculator lets you enter your estimated Social Security benefit to compute an adjusted FIRE number. Check your estimate at ssa.gov/myaccount.

A Roth conversion ladder is a strategy where you systematically convert traditional IRA/401(k) funds to Roth IRA during early retirement — when your earned income is low and you're in the 10–12% federal tax bracket. In 2026, the standard deduction is $16,100 for single filers, sheltering the first $16,100 of conversions from federal tax entirely. The 0% long-term capital gains threshold is $49,450 of taxable income (single) — keep your total taxable income at or below this level and capital gains are also tax-free. Because taxable income = gross income − standard deduction, a single filer with no other income can convert up to $65,550 gross ($49,450 + $16,100) while remaining in the 0% LTCG zone; capital gains from a taxable brokerage reduce this headroom dollar-for-dollar. Money converted must wait 5 years before penalty-free withdrawal, so starting early is key. This calculator shows how many years you have before RMDs force taxable withdrawals — age 73 for those born 1951–1959, or age 75 for those born 1960 or later (SECURE 2.0 Act).

Healthcare is one of the most underestimated FIRE costs. If you retire before 65, you'll need private coverage for up to 20+ years before Medicare eligibility. Options include ACA marketplace plans ($300–$700+/month for a healthy adult), a working spouse's plan, or COBRA (expensive, 18-month max). Crucially, keeping your Modified AGI at or below 400% of the Federal Poverty Level ($63,840 for a single person in 2026) qualifies you for ACA Premium Tax Credits. Note: the enhanced subsidies from the Inflation Reduction Act expired December 31, 2025 — in 2026, earning even $1 over the 400% threshold eliminates your entire subsidy. This calculator shows your total healthcare bridge cost so you can plan accordingly.

The Monte Carlo success rate shows the percentage of simulated retirement scenarios (out of 1,000 runs) where your portfolio survives the full withdrawal period without running out. Each run uses a different sequence of market returns, drawn randomly from historical return distributions. A 90%+ success rate is generally considered solid; below 75% suggests you may want a larger portfolio, lower spending, or a flexible withdrawal strategy like the guardrails method.

According to Morningstar's 2025 "State of Retirement Income" research — the most current academic work on the topic — the base-case safe starting withdrawal rate for a 40-year horizon is 3.1–3.3% (at 90% probability of success, fixed inflation-adjusted spending). This compares to 3.9% for a 30-year horizon. At 3.3%, your FIRE number is 30.3× annual spending, not the 25× from the 4% rule. The difference is significant: for $60,000/year in spending, 4% gives a $1.5M target; 3.3% gives a $1.82M target — a $320,000 gap. Using flexible/dynamic withdrawal strategies (adjusting spending based on portfolio performance) can allow a higher starting rate — Morningstar estimates up to 5.7% starting withdrawal for flexible spenders — but requires willingness to cut spending in down markets.

There are three IRS-sanctioned strategies: (1) Rule of 55: if you leave your employer in or after the year you turn 55, you can take penalty-free withdrawals from that employer's 401(k) or 403(b) — but not an IRA, and do NOT roll the balance to an IRA first or you lose this option. (2) 72(t) SEPP (Substantially Equal Periodic Payments): you commit to a fixed annual distribution schedule from an IRA or 401(k) for at least 5 years OR to age 59½, whichever is longer. Breaking the schedule retroactively triggers the 10% penalty plus interest on ALL prior distributions. (3) Roth conversion ladder: convert pre-tax funds to Roth now; each conversion has its own 5-year clock; after 5 years, the converted principal (not earnings) can be withdrawn penalty-free at any age. Roth contributions (not conversions, not earnings) can always be withdrawn anytime, penalty-free.

The conventional order — taxable brokerage first, then traditional IRA/401(k), then Roth last — is often wrong for FIRE retirees. The optimal strategy during your low-income early retirement years is to: (1) Draw from taxable accounts for living expenses while (2) simultaneously doing Roth conversions to fill lower tax brackets (10–12% federal). Keep total taxable income at or below the 0% LTCG threshold ($49,450 for single filers in 2026) and capital gains from your taxable account are also tax-free. (3) Leave Roth accounts completely untouched as long as possible — they have no RMDs, grow tax-free forever, and are the best inheritance assets. The RMD time bomb: large pre-tax balances will trigger forced distributions starting at age 73 (born 1951–1959) or 75 (born 1960+, per SECURE 2.0). Without proactive Roth conversions in early retirement, these RMDs can push you into the 22–24% bracket, trigger Medicare IRMAA surcharges (starting at $106,000 MAGI for single filers in 2026), and cause up to 85% of Social Security to become taxable.