Fat FIRE Calculator

Use this calculator to estimate a Fat FIRE target for a higher-spending retirement lifestyle.

What this calculator does

The Fat FIRE calculator estimates the portfolio needed for a more comfortable retirement budget. It uses a withdrawal rate, current savings, contributions, and expected return to estimate the timeline.

It uses:

• annual fat expenses
• withdrawal rate
• current savings
• annual contribution and expected return

Fat FIRE Formula

Fat FIRE Number = Annual Fat Expenses ÷ (Withdrawal Rate ÷ 100)

Where:

• Annual Fat Expenses = higher annual spending target
• Withdrawal Rate = planned annual withdrawal percentage
• Fat FIRE Number = required portfolio
• Years to Fat FIRE = time to reach the target

Example calculation

If:

• Annual fat expenses = 120,000
• Withdrawal rate = 3.5%
• Current savings = 500,000
• Annual contribution = 60,000

Then:

• Fat FIRE number = 120,000 ÷ 0.035
• Fat FIRE number = 3,428,571
• Monthly spending = 120,000 ÷ 12
• Monthly spending = 10,000

The Fat FIRE number is about 3,428,571.

What is Fat FIRE?

Fat FIRE is financial independence based on a higher level of annual spending. It usually requires a larger portfolio and often a more conservative withdrawal rate.

Why Fat FIRE matters

• plans for a more flexible retirement lifestyle
• includes a larger spending buffer
• helps compare comfort and timeline tradeoffs
• supports high-income retirement planning

When to use this calculator

• planning a higher-spending retirement
• comparing lean, standard, and fat FIRE
• estimating a conservative withdrawal target
• testing high contribution scenarios

Common mistakes

• underestimating lifestyle inflation
• using an aggressive withdrawal rate
• ignoring taxes on large withdrawals
• assuming high income will continue indefinitely

Fat FIRE vs Lean FIRE

Fat FIRE targets higher annual spending and a larger portfolio. Lean FIRE targets lower spending and a smaller portfolio.

The formula is similar, but the lifestyle assumption is very different.

FAQs

What is Fat FIRE?

Fat FIRE is financial independence designed around a higher-cost, more comfortable retirement lifestyle.

How do you calculate Fat FIRE?

Divide annual fat expenses by the withdrawal rate, then estimate how long it takes to reach that portfolio.

What is a good Fat FIRE number?

A good Fat FIRE number covers desired spending, taxes, healthcare, travel, and a large safety margin.

What is the difference between Fat FIRE and Lean FIRE?

Fat FIRE needs a larger portfolio for higher spending. Lean FIRE uses a smaller budget and target.