What is Fat FIRE?
Fat FIRE is Regular FIRE aimed at a full, no-compromises lifestyle. The math is identical — it's the spending assumption that's different. Rather than trimming costs to get there faster, Fat FIRE keeps spending at whatever level actually reflects the life you want, and builds a larger portfolio to match.
This calculator uses the same nominal approach as Regular FIRE: your portfolio grows at your expected investment return (10% by default), and only your everyday lifestyle spending rises with prices each year — a fixed mortgage repayment doesn't inflate, since it's already a fixed amount.
How to use this calculator
Use it exactly like the Regular FIRE calculator — enter your total annual spending, invested assets, monthly investment amount, and current age. For Fat FIRE, that spending figure is typically toward the higher end, reflecting a lifestyle with plenty of room for travel, dining out, and discretionary spending without needing to cut back in retirement. If part of your spending is a mortgage, add the monthly repayment and years remaining separately, since that payment won't rise with inflation the way the rest of your spending will.
What is the 4% rule?
The 4% rule works the same way here as anywhere else: divide your annual spending by 4% (or multiply by 25) for a rough FIRE number. A higher spending target means a proportionally larger portfolio — and larger dollar amounts at stake if markets fall shortly after you retire, so sequence-of-returns risk is worth paying extra attention to at higher spending levels. You can adjust the withdrawal rate in the advanced settings between 2.5% and 6%.
Fat FIRE vs Regular FIRE
Fat FIRE isn't a different formula — it's Regular FIRE with a larger spending target. It usually takes longer to reach than a leaner number, but preserves your full lifestyle without needing to compromise once you get there.
Frequently asked questions
How is Fat FIRE different from just having a big portfolio? It isn't — Fat FIRE simply describes reaching FIRE while maintaining a high, comfortable spending level rather than cutting back to get there sooner.
Does a bigger portfolio need a different withdrawal rate? Not necessarily, but because the dollar amounts involved are larger, some Fat FIRE retirees choose a slightly more conservative withdrawal rate to guard against a poor sequence of returns early on.
Can I start with Regular FIRE and upgrade to Fat FIRE? Yes — plenty of people keep investing past their Regular FIRE number specifically to build in more margin or a higher standard of living.
Does this calculator account for tax? Yes, there's an optional tax slider on withdrawals, set to 0% by default. When it's above zero, the calculator shows how much of each withdrawal you actually keep.
What if I have a mortgage? Enter the monthly repayment and years remaining separately from your other spending. It's treated as a fixed nominal payment that doesn't rise with inflation, and drops off your required spending once it's paid off.
Why does my FIRE number look bigger than other calculators? By default, results are shown in future dollars — the actual amount your portfolio will be worth by the time you retire, after years of inflation. You can switch to today's dollars in the "Why does this look different?" expandable on the FIRE number card; either way, the retirement date it points to is the same.