Coastfire Calculator
Calculate how much you need to invest now to reach your retirement goal without further contributions, based on the Coast FIRE concept.
Published by:
isCalculator Editorial Team
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How to Use the Coastfire Calculator
This calculator helps you determine how much you need to invest today to reach financial independence by retirement age, assuming your investments grow without additional contributions.
- Enter your current age (e.g., 30). Must be less than retirement age.
- Enter your desired retirement age (e.g., 65).
- Enter your desired annual retirement spending in dollars (e.g., 40,000). This is the amount you plan to withdraw each year in retirement.
- Enter your expected annual return as a percentage (e.g., 7 for 7%). Default is 7%.
- Enter your current savings in dollars (optional, default is $0). This is money you already have invested.
- Click "Calculate Coastfire Number".
What the result means: The calculator shows the additional amount you need to invest today (in today's dollars) so that it grows to your FIRE number (25x your annual spending) by retirement age, given your expected return. If you already have enough savings, the result will be $0.
Note: All monetary values are in US dollars. Returns are assumed to be constant and compounded annually. This is a simplified model.
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Frequently Asked Questions
Coast FIRE is a financial independence approach where you save enough money early on that, with compound growth, will grow to your desired retirement nest egg by the time you reach traditional retirement age, without needing to save more.
The calculator first determines your FIRE number (25 times your annual spending). Then it discounts that number back to today using your expected annual return and the number of years until retirement. Finally, it subtracts your current savings to show how much more you need to invest now.
It assumes a constant annual return rate and that you will not make additional contributions after the initial investment. It also uses the 4% rule (25x annual spending) to estimate your retirement nest egg.
