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FAT FIRE Calculator

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The journey towards financial independence and retiring early (FIRE) is a path many dream of but often consider out of reach. However, with the right tools and planning, achieving a comfortable or even luxurious early retirement is possible. This is where the FAT FIRE Calculator comes into play, a powerful tool designed to help you map out your financial future with precision.

What is FAT FIRE?

FAT FIRE goes beyond the conventional FIRE movement by aiming for a higher standard of living in retirement. Instead of minimizing expenses to retire as early as possible, FAT FIRE enthusiasts save and invest to maintain or enhance their lifestyle. This approach requires a larger nest egg but promises a more comfortable retirement phase.

How Does the FAT FIRE Calculator Work?

The FAT FIRE Calculator is a simple yet effective tool that uses specific financial variables to estimate how much money you need to save before retiring and how long it will take to reach your goal. The variables considered in the calculator include:

  • S: Your current savings
  • A: Your expected annual spending in retirement
  • R: The annual rate of return on your investments
  • W: The safe withdrawal rate from your investments during retirement
  • Y: The number of years you plan to work before retiring

Using these variables, the calculator applies two main formulas:

  1. Required Nest Egg: Required_Nest_Egg = A / W
  2. Years Until Retirement: Y = (log((Required_Nest_Egg * R + A) / (S * R + A))) / (log(1 + R))

These formulas help you understand the size of the financial cushion you need and the timeframe to achieve it, considering your desired lifestyle in retirement.

Step-by-Step Example

Let's go through a simple example to illustrate how the FAT FIRE Calculator works:

  • Current savings (S): $100,000
  • Annual spending in retirement (A): $40,000
  • Annual return on investments (R): 7% (or 0.07 as a decimal)
  • Safe withdrawal rate (W): 4% (or 0.04 as a decimal)

First, calculate the required nest egg:

Required_Nest_Egg = $40,000 / 0.04 = $1,000,000

Next, calculate the years until retirement:

Y = (log(($1,000,000 * 0.07 + $40,000) / ($100,000 * 0.07 + $40,000))) / (log(1 + 0.07)) ≈ 23.45 years

This means, with the given parameters, you would need to save approximately $1,000,000 and could potentially retire in about 23 years.

Relevant Information Table

Here's a table showcasing different scenarios with varying annual spending and savings to achieve FAT FIRE:

Current SavingsAnnual SpendingRequired Nest EggYears Until Retirement


The FAT FIRE Calculator is an invaluable resource for those aspiring to a financially secure and luxurious early retirement. By inputting your current financial status and retirement goals, you can receive a personalized roadmap to your dream retirement. The calculator simplifies complex financial planning into actionable steps, making the dream of a comfortable early retirement accessible to more people. Whether you're just starting your savings journey or you're well on your way, the FAT FIRE Calculator can help guide your path to financial independence and a rewarding retirement.

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