Coast FIRE Calculator

Calculations use a real-return approach where nominal expected return is adjusted by expected inflation to produce an estimated real annual return. This avoids mixing nominal growth assumptions with inflation-adjusted spending targets.

Target portfolio is computed by dividing desired annual retirement spending by the chosen withdrawal rate. The 'coast' amount is the present value of that target portfolio discounted by the real return for the number of years until target age.

This tool follows best-practice guidance for transparency and reproducibility. It documents inputs, uses explicit formulas, and includes caveats about model limitations. For computational integrity and data handling, follow applicable standards such as NIST guidance for data integrity and ISO/IEEE standards for software quality. This calculator does not provide legal, tax, or investment advice.

Example 1: Age 35, want to retire at 60, $40,000/year spending, 4% withdrawal rate, 7% nominal return, 2.5% inflation. The tool computes the coast lump sum and shows whether current savings will grow to meet it.

Example 2: If current savings are below the coast amount, the tool shows the additional lump sum needed today or the annual contributions required to reach the target by the retirement age.