Coast FIRE Calculator
Estimate how much invested today would need to compound, without new contributions, to reach a FIRE target at a chosen retirement age.
These are deterministic planning assumptions. They do not model market volatility, taxes, fees, Social Security, pensions, or changes in spending.
Your inputs stay on this page and are not saved.
The current portfolio is above this deterministic Coast FIRE estimate.
- Portfolio target at retirement
- $1,200,000.00
- Years of assumed growth
- 35
Coast FIRE assumes no additional contributions are needed after reaching the displayed amount. Actual returns can be lower or negative.
How the calculation works
Retirement target = annual spending ÷ withdrawal rate. Coast FIRE number today = retirement target ÷ (1 + estimated real return) ^ years remaining.
The result assumes a constant annual return after inflation and no future contributions. Actual returns vary, may be negative, and do not arrive in a smooth sequence.
Reference: Investor.gov: Compound Interest Calculator
Coast FIRE Calculator FAQs
What does Coast FIRE mean?
Coast FIRE describes having enough invested today that, under an assumed return and timeframe, the portfolio could grow to a future financial independence target without additional contributions.
How is the Coast FIRE number calculated?
First calculate the future target from annual spending and a withdrawal rate. Then discount that target back by the assumed annual real return across the years until retirement.
Why use a real return after inflation?
The spending and target are entered in today’s dollars. A real return keeps the growth assumption on the same purchasing-power basis by accounting for inflation.
Does reaching Coast FIRE mean I can stop working?
No. It only addresses the modeled future portfolio target. Current living costs still need funding, and actual returns, taxes, fees, and spending may differ.
Can Coast FIRE be lost after reaching it?
Yes. Market declines, lower future returns, a shorter timeframe, higher planned spending, or a lower withdrawal rate can move the estimate above the current portfolio.
Why does the result change so much with the return assumption?
Compounding magnifies small rate differences over long periods. Test several conservative return assumptions instead of treating one result as a forecast.