Coast FIRE Calculator

Coast FIRE is the point where your investments, left alone, would grow into your full retirement target by retirement age — so every contribution after that is optional. Enter your target nest egg, current investments, expected return and years left to find your Coast number and your gap.

Results

Assumptions: A constant annual return with no taxes, fees or withdrawals along the way. Real returns arrive unevenly, which changes outcomes.

Formula

The Coast number is the present value of your target at your expected return:
Coast number = Target ÷ (1 + return)years
Every year that passes raises the required number, because growth has less time to work.

How to use this calculator

  1. Enter the nest egg you want at retirement.
  2. Enter what you have invested today, an expected long-run return and the years remaining.
  3. Press Calculate to see your Coast number and whether you have passed it.
Coast FIRE Calculator — how the calculation works, illustrated
Coast FIRE Calculator — how the calculation works, illustrated

Worked example

Target $1,000,000, 25 years to retirement, 7% expected return.

  1. Growth factor: 1.07²⁵ ≈ 5.4274.
  2. Coast number: 1,000,000 ÷ 5.4274 ≈ $184,249.

Result: You would need about $184,249 invested today to coast; $50,000 today projects to about $271,371 — short of the target, so contributions still matter.

Frequently asked questions

Does Coast FIRE mean I can stop working?

No — it means you could stop saving for retirement and let growth finish the job, while still earning enough to cover current living costs. Full FIRE requires the whole target today.

What return should I assume?

Long-run diversified stock portfolios have historically averaged roughly 7% after inflation in the US, but past performance does not guarantee future results. Many planners test 5–7% to be conservative.

How do I pick a target nest egg?

A common starting point is 25× your expected annual retirement spending (the inverse of the 4% guideline). It is a rough planning heuristic, not a guarantee of safety.

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