Fat FIRE calculator
Fat FIRE describes financial independence with a larger spending budget. The label has no universal portfolio threshold: a comfortable budget depends on your household, commitments and choices.
Use this calculator to see what a spending plan implies for a portfolio target. It cannot judge how much is enough for you. This is not financial advice.
Separate commitments from flexible spending
Start with the annual spending you expect the portfolio to support. Separate ongoing commitments from expenses you could postpone or reduce. Housing, dependents and healthcare may behave differently from optional travel or large purchases.
Include tax allowances and investment fees consistently. This calculator does not calculate tax bills, and a pre-tax account balance is not the same thing as cash available to spend after tax.
Enter all spending in today’s dollars. Do not inflate the budget into future dollars and then compare it with a target calculated in today’s dollars.
Calculate a spending-based target
Illustrative portfolio target = annual portfolio-funded spending ÷ initial annual withdrawal rate
Enter your own higher-spending annual budget and withdrawal assumption above. The target is spending ÷ rate for the values you provide.
These are example inputs, not a definition of Fat FIRE or a recommendation. A large portfolio can still face losses, tax costs and a retirement longer than expected. The formula does not measure the probability of running out.
Explore a range instead of one finish line
Compare a core budget with a broader wish-list budget. A larger one-off purchase should be considered explicitly rather than hidden in recurring annual spending without explanation.
An earlier retirement may mean more years of withdrawals. A fixed initial withdrawal percentage alone does not account for retirement length, market conditions or the order of returns.
Use the FIRE number calculator to understand the target formula. If you intend to keep working while the portfolio grows without more deposits, take the target to the Coast FIRE calculator.
Questions about higher-spending plans
Is there a minimum Fat FIRE number?
Not on this site. The useful starting point is an itemized budget rather than a label attached to an arbitrary balance.
Can I assume the optional spending will disappear during a downturn?
Only you can judge how flexible it really is. Try a second scenario rather than treating a future spending cut as certain.
Model and transparency
Last updated: 6 November 2026. Deterministic annual calculations, not a historical success test. This is not financial advice.
Method and limitations · About the operator · Storage and privacy