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Coast FIRE Calculator

How to use

Coast FIRE Calculator is a tool calculating how much you need to 'coast' Financial Independence, and how long it will take.

  • Retirement Age: The age when you want to reach FIRE goal
  • Monthly contribution: How much money can you save each month for Coast FIRE, and you can stop contributing once you reach the Coast FIRE requirement
  • Growth: Your saving growth (for example, S&P 500 normally is 7%)
  • The Safe Withdrawal Rate (SWR) is the percentage of your assets you plan to withdraw each year after reaching early retirement. Generally, 4% is considered a relatively safe rate—it means you need to save 25 times your annual expenses. A lower withdrawal rate is safer or easier to sustain, but it also means you'll need to save more money.

What is Coast FIRE

Coast FIRE (or CostFIRE) refers to a financial strategy where you save a lump sum in the short term, let that money grow on its own over time, and then continue working at a job you enjoy just to cover your daily expenses. In other words, you live frugally for a few years, save up a solid amount, and then you can become a relaxed and happy "living paycheck-to-paycheck" person — by choice, not necessity.

Coast FIRE formula

This calculator is built on the standard FIRE calculator, with one additional step included. This is how to calculate your FIRE number:

The formula to calculate your FIRE number using the Safe Withdrawal Rate (SWR) is:

FIRE formula

The formula to calculate your end-of-year savings is:

FIRE formula

Compound interest calculation is one of the core components of the entire calculator.

The standard compound interest formula is:

FIRE formula

The formula to calculate your Coast FIRE number is:

FIRE formula
  • Annual Spending = the amount of money you plan to spend per year in retirement
  • SWR = Safe Withdrawal Rate (as a decimal, e.g. 0.04 for 4%)
  • n = expected annual growth rate of your investments (as a decimal)
  • t = number of years until retirement