Coast FIRE Calculator UK — Find Your Coast Number
Estimate a pot that could reach your retirement target without further contributions. Compare return and withdrawal assumptions, in today's pounds.
What is a Coast FIRE calculator?
A Coast FIRE calculator estimates the pot needed today to reach a later retirement target through investment growth, assuming no further contributions or withdrawals. Retirement target = annual amount needed ÷ withdrawal rate; coast target = retirement target ÷ (1 + real return)^years. For £30,000 a year, a 4% withdrawal assumption and 35 years of 4% real growth, the illustrative coast target is about £190,062. It is not guaranteed retirement income.
Coast FIRE is a planning milestone within the Financial Independence movement. It explores whether an existing invested pot could reach a future target through growth while you fund current living costs separately. It can help compare work and saving choices, but the answer depends on returns, spending, costs and when you need access to the money.
A 4% initial withdrawal assumption gives a retirement target of 25× the annual amount needed from investments. Discount that target using your assumed real return and years until retirement to get today's coast target. Changing either rate can change the answer substantially; the scenario table below makes that visible.
Coast FIRE Calculator
Today's pounds. Include withdrawal tax where relevant; this tool does not calculate it.
Total invested, including any employer payments and tax relief. Assumed at year-end and held constant in today's pounds.
After inflation, investment fees and any tax drag. The 4% default is an illustration, not a forecast; zero and negative scenarios are supported.
4% implies a target of 25× the annual amount needed; 3% implies 33.3×. Neither guarantees lasting income.
Coast FIRE Number
£190,062
Required today under your selected assumptions, in today's pounds.
Full FIRE Number
£750,000
Target pot at retirement age 65.
Progress to Coast
26.3%
Years to Coast
21
Uses the remaining growth time at each age; yearly checkpoints, first met at age 51.
The illustrative target today is £190,062. With no further contributions, your existing pot projects to £197,304 by age 65 at a constant 4% real return. With £10,000 invested at each year-end, the first yearly coast milestone is in 21 years.
How assumptions change your coast target
Same ages and annual need; only return and withdrawal assumptions change. These are illustrations, not probabilities or recommended rates. All values are in today's pounds.
| Real return | Coast target at 3% withdrawal | Coast target at 4% withdrawal |
|---|---|---|
| 2% | £500,028 | £375,021 |
| 4% | £253,415 | £190,062 |
| 6% | £130,105 | £97,579 |
This models constant growth before retirement, not investment volatility, withdrawal sustainability or the effect of market losses early in retirement. No withdrawals before retirement are included.
Illustrative growth: keep contributing vs stop today
Green: stop contributing today. Blue: keep investing £10,000/year right through to retirement, even after a coast milestone. Both assume constant real growth, no withdrawals, and show today's pounds.
How Coast FIRE Works
- •Coast FIRE estimates a pot that could grow to your retirement target without further contributions if your assumptions hold.
- •Formula:
Coast Number = FIRE Number ÷ (1 + return)^years to retirement - •A coast milestone does not establish that part-time earnings cover your living costs or that future retirement income will be sufficient.
- •Uses real returns after inflation and costs. Contributions must keep pace with inflation to remain constant in today's pounds.
- •UK note: normal minimum pension age is generally 55, rising to 57 on 6 April 2028, with protected-age and other exceptions. This model does not check accessible bridge funds, pension withdrawal tax or State Pension timing.
What a coast milestone can and cannot tell you
Meeting the model's coast target does not establish that retirement is funded. This projection assumes constant annual real growth and no withdrawals before retirement. It does not simulate market volatility, losses early in drawdown, changing spending or how long withdrawals must last. A lower assumed return or withdrawal rate raises the required pot; revisit the plan as circumstances change.
For UK planning, distinguish an invested pot from money you can access. Normal minimum pension age is generally 55, rising to 57 on 6 April 2028, with protected-age and other exceptions. Check your scheme's rules. The calculator does not separate pensions from accessible ISA or taxable-account savings, calculate withdrawal tax, or fund the gap before pension access or State Pension age.
Contributions are the total reaching the investments, including any employer payments and tax relief; neither is automatically added. Pension allowances and limits on tax relief can restrict contributions. The usual annual allowance is £60,000, but tapering or the money purchase annual allowance can reduce it, and personal tax relief has separate earnings limits.
Sources checked 9 October 2026: HMRC pension access ages, pension annual allowance, pension tax relief limits and MoneyHelper on investment risk in retirement.
Frequently Asked Questions
What's Next?
Early retirement bridge guide
Separate accessible savings from pension money before access age.
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