Fat FIRE Calculator
Calculate your Fat FIRE number for a comfortable early retirement, including taxes on withdrawals and other income, and how many years until you get there.
Fat FIRE is financial independence without cutting back: a portfolio big enough to fund a generous lifestyle with travel, a nice home and room for surprises. At high spending levels taxes on withdrawals matter, so this calculator grosses up your budget for tax, subtracts any other retirement income, and divides by a cautious withdrawal rate to get your Fat FIRE number and the years it takes to reach it.
How to use this tool
- Enter your age, current investments and the yearly lifestyle budget you want.
- Enter your expected effective tax rate on withdrawals and any other after-tax income.
- Enter how much you invest each year and an after-inflation return.
- Choose a withdrawal rate — 3–3.5% is common for retirements that may last 40+ years.
- Read your target, the timeline and the yearly table.
Formula
Target = (spending − other income) ÷ (1 − tax rate) ÷ withdrawal rate
Years n = ln((T + C/g) ÷ (P + C/g)) ÷ ln(1 + g)
P is what you have invested, C what you add each year, g the real return and T the target. Using a real return keeps every figure in today's dollars, so the target is what you would need if you retired now.
Example
Someone aged 35 with $800,000 invested wants $120,000 a year after tax. At a 15% effective tax rate they need to withdraw $141,176, and at a 3.5% withdrawal rate the Fat FIRE number is about $4.03 million. Investing $90,000 a year at a 5% real return gets there in about 16.6 years, at around age 51 and a half.
Frequently asked questions
How much spending is Fat FIRE?
There is no official line. In FIRE communities it usually means spending around $100,000 a year or more, well above a typical household budget — but the idea is about comfort, not a fixed number.
Why include taxes?
Withdrawals from pre-tax retirement accounts are taxed as income, and gains in taxable accounts may be taxed too. A $120,000 lifestyle can need noticeably more than $120,000 of withdrawals.
Should I use 4% or a lower withdrawal rate?
The 4% guideline was tested on 30-year retirements. Retiring in your 40s or early 50s may mean 40–50 years of withdrawals, so many planners suggest 3–3.5%, which raises the target by 14–33%.
This tool gives an estimate for general information only. It is not financial, tax, legal or medical advice — check with a qualified professional before you rely on the result.
Last updated: 2026-10-30