Coast FIRE

Coast FIRE is about time, invested assets, and assumed growth.

The Coast milestone in Undefeated uses your Financial Independence Year and current inputs. Ambit explains the assumptions behind the idea.

Question this answersHow does Coast FIRE relate to the inputs in a Financial Independence Year estimate?
Simple termsEstimate, not adviceExplains calculator inputs
  1. 01
    What it means

    Start with the plain meaning.

  2. 02
    How it affects the year

    See how this connects to the estimate.

  3. 03
    What to check

    See what the estimate leaves out.

Why this matters

What this means.

Coast FIRE asks whether existing investments might do enough of the later work if given time. That can be useful context, but it depends heavily on assumptions.

Year impact

How this can move the year.

More invested assets or a higher assumed real return can move the estimated Financial Independence Year earlier. The separate Coast milestone uses the time until that year. Lower returns, higher spending, or a higher portfolio target can move it later.

How it is used

How the calculation uses it.

The optional Coast milestone tests whether contributions might end before your Financial Independence Year. The Financial Independence Year remains the main answer for when work could become optional.

Estimate limits

What can make the estimate change.

The idea can lose usefulness if return assumptions are too high, fees are missing, spending changes, or the time horizon is shorter than expected.

Checks

Checks before you use the number.

Use these prompts to read the estimate carefully. They are not recommendations.

  • Check expected real return carefully, because Coast FIRE is sensitive to compounding.
  • Check whether monthly savings are being tested as continuing, reduced, or paused.
  • Use the result as learning context, not as a status label or instruction.

Related calculator

Calculate your Financial Independence Year

Create your Financial Independence Year first. The optional Coast milestone then uses the same inputs and result.

Open calculatorSee how the year is calculated

Read next

Read one assumption at a time, then use the calculator when you want to test the inputs.

Next in this path 2 of 4Compound interestUse this UK compound interest calculator to see how starting amount, monthly contributions, time, and a nominal or real return assumption can shape a future pot. It does not calculate when work becomes optional; Undefeated’s main calculator turns assumptions into your Financial Independence Year.

Related assumptions

Open calculatorUnderstand with Ambit