FIRE calculator UK

FIRE Calculator UK

Use Undefeated to estimate your Financial Independence Year: the first year projected assets meet the spending threshold and the duration requirement, based on the assumptions you enter.

Question this answersWhat does a UK FIRE calculator need to estimate when work can become optional?
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.

A FIRE calculator is useful only when its assumptions and checks are visible. Undefeated shows the year work could become optional, then explains which tested input change makes the biggest difference.

Year impact

How this can move the year.

The Financial Independence Year can shift when spending, savings, invested assets, expected real return, or the portfolio target changes. Reading those inputs together makes the estimate easier to understand.

How it is used

How the calculation uses it.

The calculator uses the values entered and returns the first year both capital checks pass. Tax rules, pension access, fees, debts and changes at home are not modeled separately; your estimate depends on the values you enter.

Estimate limits

What can make the estimate change.

Check that your inputs are complete. Changing spending or expected real return can move the estimate; future rules and actual returns may differ from what this model assumes.

Checks

Checks before you use the number.

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

  • Check that monthly spending reflects the life you want to test.
  • Check that invested assets and monthly savings are entered consistently.
  • Read the assumptions before treating the year as more than a planning estimate.

Curated context

UK sources for reading the assumptions.

These rows are included because they explain inputs behind the Financial Independence Year. They do not replace the calculator or the method.

Spending

The lifestyle being tested starts with the spending input.

Contributions

Regular additions change how quickly projected assets approach both capital checks.

Return setting

After-inflation growth affects the path between today and the year.

Portfolio target and withdrawal rate

Tools uses a portfolio target multiple. A withdrawal rate is its reciprocal description; the duration check remains separate.

Pension access

Access timing can change how someone reads the bridge to later pension income.

Tax wrappers

Wrappers can affect which money is available before later pension access.

Coast FIRE

Coast is a supporting milestone from assumptions, not the main answer; it does not mean work is optional today.

Understand Coast FIRE
  • MoneyHelperHow much should I save for retirement?
    official guidanceRelated assumption: spending
    Date
    02 July 2026
    Last reviewed
    10 August 2026

    Summary

    MoneyHelper explains how retirement spending estimates can be framed around UK living-cost assumptions.

    Why this matters

    Spending is one of the assumptions that shapes the Financial Independence Year.

    Read source
  • GOV.UKCheck your State Pension forecast
    official guidanceRelated assumption: pension access
    Date
    Publication date not shown
    Last reviewed
    10 August 2026

    Summary

    GOV.UK provides the official route for checking State Pension forecast information.

    Why this matters

    Pension timing can change how someone reads the gap between a work-optional year and later pension income.

    Read source
  • Which?How much will I need to retire?
    editorial contextRelated assumption: spending
    Date
    01 July 2026
    Last reviewed
    10 August 2026

    Summary

    Which? frames retirement income needs through UK lifestyle and spending examples.

    Why this matters

    It gives another way to check whether the spending input reflects the lifestyle being tested.

    Read source

Curated for education only. Sources are not endorsements and this is not financial advice.

Calculator connection

Calculate your Financial Independence Year

Open the calculator to test spending, invested assets, contributions, real return, and the portfolio target in one place.

Open the calculatorSee how the year is calculated

FAQ

Questions people usually bring to this page.

What is a FIRE calculator?

A FIRE calculator estimates when projected assets may meet its modelled spending requirements, using assumptions such as current assets, contributions, returns, spending, and a portfolio target.

What does Undefeated calculate?

Undefeated calculates a Financial Independence Year: the first year projected assets meet both the spending threshold and the duration requirement, based on the inputs you enter.

What is a Financial Independence Year?

It is the estimated year work could become optional because projected investments may cover annual spending under the assumptions entered.

Is this retirement advice?

No. Undefeated is an educational calculator, not retirement advice, investment advice, tax advice, or pension advice.

What assumptions move the year?

Spending, invested assets, contributions, expected real return, and the portfolio target can all move the Financial Independence Year.

Is Coast FIRE the same as Financial Independence?

No. Coast FIRE is a milestone lens on whether an invested amount may grow toward a future retirement target. It is different from the Financial Independence Year.

Is this financial advice?

No. The calculator and Ambit explainers are educational only and not financial advice.

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 2Retire questionState Pension age is a separate rules question. Undefeated estimates the year work could become optional from the assumptions entered.

Related assumptions

Open calculatorUnderstand with Ambit