The FatFIRE number,
and how far you are from it

What FatFIRE actually is

The FIRE movement split into tiers around 2015. Mr. Money Mustache had already published the LeanFIRE archetype — $25k to $40k a year, $1M portfolio, live below the median and retire at 40. Then r/financialindependence got popular. Then r/fatFIRE broke off. The subreddit's stated definition: $200k+ in annual after-tax spend, or $10M+ in investable assets, or 25× spend at higher spend levels. That's the operational threshold.

Here's how the three tiers usually look side by side:

• LeanFIRE — $40k a year, $1M portfolio, roughly 4% SWR. Requires a low-cost-of-living location or a paid-off home in a cheaper city. Owner-operated Airbnb, no private school, driving a used Corolla. Common at r/leanfire.
• Regular FIRE — $80k a year, $2M portfolio, 4% SWR. Median FIRE demographic. Owns a modest home, travels once a year internationally, kids in public school.
• FatFIRE — $250k+ a year, $10M+ portfolio, 3-3.5% SWR. Same lifestyle you had at peak earnings, minus the commute. Business class, private school if you want it, a second home isn't unusual.

Chubby FIRE is the interstitial category — $150k on $4M-ish. It's real, the term shows up on Bogleheads all the time, but it isn't a separate math problem. Just Regular FIRE with a bigger number.

The 4% rule, its critics, and why FatFIRE aims at 3.5%

William Bengen's 1994 paper (published in the Journal of Financial Planning) ran a Monte Carlo across 1926-1992 US market data and asked: what's the maximum first-year withdrawal, indexed to inflation each year after, that survives every 30-year window? The answer was 4%. That number became the load-bearing assumption for two decades of retirement planning.

Bengen updated the number in 2020 to 4.7%, and again in 2022 to around 4.5% after CPI shocks. Michael Kitces has published half a dozen posts pushing back on both directions — he thinks 4.5% is about right for a 30-year horizon at moderate valuations. Wade Pfau, at the American College, argues for lower rates at high CAPE ratios. There's no consensus, and there won't be, because the answer depends on what you plug into the model.

FatFIRE has a specific problem: the horizon. If you retire at 42, you're looking at 45-55 years of drawdown. Every model degrades past 30 years because the tail probability of running out grows nonlinearly. Practitioners handling FatFIRE households (like Cody Garrett at Measure Twice, or the Bogleheads long-thread consensus) tend to land at 3-3.5% for those horizons. That's why the calculator above defaults to 3.5%, and why $250k of spend asks for $7-8M of portfolio, not $6.25M at 4%.

Sequence-of-returns risk, the FatFIRE killer

Say you retire on January 1, 2000, with a $2M portfolio and a $80k spending plan. You draw $80k on day one. Then the market drops 40% by October 2002. Now you have $1.09M left after drawdown and losses, and your $80k a year is 7.3% of the smaller balance — well above any sustainable rate. You keep spending. By 2010, after another lost decade, the portfolio is worth less than it was in 2000. You've missed the bull market of 2013-2019 by drawing down through the trough.

The mirror case: retire on January 1, 2010. The same $2M grows to $3.5M by 2015 while you're only pulling $80k a year. Now you can spend more, or leave more to heirs, or start a foundation, or all three. Same portfolio, same plan, different starting year, wildly different outcome.

The math principle: the first five years of retirement matter disproportionately. Draw down through a crash and you lock in the losses. Draw down through a bull and you get to compound the gains you don't spend. This is why FatFIRE plans usually include a bond tent (glide to 40-50% bonds around retirement, then glide back down to 70/30 equities over the next decade), or a 2-3 year cash bucket to avoid selling equities in a crash, or both.

The healthcare paradox before Medicare

You retire at 47 with $10M. Medicare starts at 65. That's 18 years of buying insurance yourself. In 2026 the ACA marketplace is still the default option, and the subsidy math is where it gets weird — the subsidy phases out based on MAGI (Modified Adjusted Gross Income), which for early retirees is often close to zero. You show up on paper looking like a low-income household even though you have millions in the bank.

Which is why the FatFIRE healthcare playbook usually looks like this: keep MAGI just above 138% of the federal poverty line (to avoid Medicaid enrollment issues but still qualify for full ACA subsidies), do Roth conversions strategically to stay under the 400% FPL cliff, and use an HSA — funded during working years — to pay medical expenses tax-free. One misplaced Roth conversion adds $25k to the year's healthcare bill.

The wrinkle: capital-gains realizations count as MAGI. If you sell $200k of appreciated stock to fund the year, you've just blown past the subsidy cliff. Drawdown order stops being an academic question. This is where a lot of newly FatFIRE'd people learn tax planning the hard way.

"One more year syndrome" and why numbers alone don't work

A weird thing happens when your portfolio hits the FatFIRE number. You don't quit. You keep working. The r/fatFIRE forum calls it One More Year Syndrome, or OMYS. Why does it happen? Two reasons.

First: sequence-of-returns anxiety. You know the math on retiring into a 2000-style drawdown, so you keep the paycheck coming for a cushion. Second: identity. If your job is who you are — and for a lot of high earners it is — hitting the number doesn't come with a permission slip to stop. The number is necessary but not sufficient.

There's no calculator fix for this. But knowing it's coming helps. Most FatFIRE households that actually pull the trigger have thought about the identity question two to three years before the money hit the target. If you're within three years of the number and haven't started, start.

If you're 3-5 years out: what to actually do

Three moves that matter more than the last percentage point of return:

1. Start the bond tent. Shift from 90/10 or 80/20 toward 60/40 over the last three years before retirement. Slide back to 70/30 or 80/20 over the first decade of retirement. The tent reduces sequence risk exactly when it matters most, without giving up long-run return.
2. Build the taxable-first drawdown order. Keep 2-3 years of spend in cash or short-term bonds. Draw from taxable brokerage first while long-term-capital-gain rates are 0-15%. Let Roth keep compounding tax-free — you'll want it in your 70s and 80s. Do partial Roth conversions in low-income years after retirement.
3. Simulate the first year of retirement while you're still working. Live for six months on the drawdown budget. If you can't do it, you're not at FatFIRE — you're at Chubby with an optimism bias. Adjust the number and keep working, or adjust the spend and pull the trigger. Both are fine answers.

Where a live net-worth view earns its keep

The SWR math on this page needs one input: total investable assets. Which sounds easy and isn't. Between a taxable brokerage, a 401(k) at a former employer, the current 401(k), a Roth IRA, an HSA, a brokerage account for a rental LLC, and cash across three checking accounts, most FatFIRE households can't produce a single accurate number without twenty minutes of spreadsheet work. Which means the SWR question doesn't get asked often enough.

The whole point of wlthy is to make that number live and correct. Every account, one view, refreshed. Feed the number back into this calculator any Sunday morning you feel like it, and see how the FatFIRE date moved this quarter. Which is a healthier ritual than checking the S&P daily.