Fat FIRE Calculator

What is Fat FIRE?

Fat FIRE is the variant of early retirement that refuses to cut spending. Where Lean FIRE engineers a deliberately small budget and Standard FIRE assumes a typical one, Fat FIRE sizes the portfolio to an above-average lifestyle — the usual convention is $100,000 a year or more, with the same house, the same travel, the same restaurants. You size the portfolio to your life, instead of sizing your life to the portfolio.

The threshold is a community convention, not an official line — some reserve "Fat" for $150,000 or $200,000 a year. The defining idea is constant: no downsizing required.

The math

There's no special Fat FIRE formula. Like every FIRE number, it's annual expenses divided by a safe withdrawal rate:

Fat FIRE Number = Annual Expenses ÷ Safe Withdrawal Rate

At $100,000/yr and a 4% withdrawal rate, that's $2,500,000 (25× expenses). At a more conservative 3%, the same budget needs $3,333,333 (about 33×). The target scales linearly with spending: every extra $10,000/yr of lifestyle adds $250,000 at 4%.

Fat FIRE is ordinary FIRE math on a bigger number — and usually a more cautious withdrawal rate.

Fat FIRE targets at common budgets

Rounded to the nearest $1,000:

Why Fat FIRE often uses a lower withdrawal rate

The 4% rule was calibrated for roughly 30-year retirements. Fat FIRE plans usually run longer — retiring in your 40s on a big budget can mean a 40–50-year horizon — and the entire premise is not having to trim spending in a bad market. That margin has to come from somewhere, and the cleanest place to put it is the withdrawal rate. That's why this calculator defaults Fat FIRE to 3.5% rather than 4%. Lower the rate and the target rises; the calculator shows the trade-off instantly. For the evidence behind 3–3.5% versus 4–5%, see what the 4% rule actually says and sequence-of-returns risk, the reason the first decade of retirement matters most.

Fat vs Standard vs Lean FIRE

The three variants differ only in the spending band you plug in:

• Lean FIRE — under ~$40k/yr; under $1M at 4%. Tightest lifestyle, earliest exit.
• Standard FIRE — $40k–$100k/yr; $1M–$2.5M at 4%. Typical middle-class spending.
• Fat FIRE — $100k+/yr; $2.5M and up. No downsizing, longest savings timeline.
• Coast FIRE and Barista FIRE — partial variants: stop saving early, or cover the gap with part-time work.

One caution the math makes plain: a $100k/yr lifestyle makes a high savings rate expensive in absolute dollars, so Fat FIRE timelines are long unless income is high enough to fund both the spending and the saving. Check your own rate with the savings rate calculator — it's the single biggest driver of how soon you get there.