What Is Coast FIRE? How to Know If You've Already Reached It

What Is Coast FIRE?

Coast FIRE is a milestone that sits between where you are now and full financial independence. You have reached Coast FIRE when your current investment portfolio is large enough that — left entirely alone, with no further contributions — it will grow to your full FIRE number by the time you want to retire.

The name is deliberate. Once you hit this threshold, you can “coast” the rest of the way to retirement. You no longer need to save and invest aggressively. You just need to earn enough to cover your current living costs — and compounding does the rest.

This is a fundamentally different relationship with work. Most people are trapped: they must keep earning, keep saving, keep investing just to stay on track. A person who has reached Coast FIRE has permanently broken that dependency. Their retirement outcome is no longer tied to their savings rate. Time is now working entirely in their favour.

How to Calculate Your Coast FIRE Number in the UK

The formula is straightforward:

Where:

• Full FIRE Number — your total target portfolio (annual spending × 25 at a 4% withdrawal rate, or × 28.5 at 3.5%)
• Annual return — expected real return after inflation; 5% is a conservative long-run estimate for a globally diversified index fund portfolio
• Years to retirement — the number of years between now and your target retirement age

Worked example: Suppose you want to spend £30,000/year in retirement, giving you a full FIRE number of £750,000 (at 4% SWR). Your target retirement age is 60. You are currently 38 — so 22 years away. Assuming 5% real annual returns:

If you already have £256,400 invested today — across your ISA, SIPP, and any other investment accounts — you have reached Coast FIRE. You never need to invest another penny for retirement. Every additional contribution from here simply pulls your retirement date forward.

You can run this calculation instantly with the UK Coast FIRE Calculator.

Coast FIRE Numbers at Every Age

The table below shows the Coast FIRE number required today to reach a £750,000 full FIRE target, at two common target retirement ages, assuming 5% real annual returns. This is a standard FIRE target for someone spending £30,000/year in retirement.

Target portfolio: £750,000 (£30,000/year spending at 4% SWR). Assumes 5% real annual returns. No additional contributions modelled.

Notice how much the target retirement age matters. A 35-year-old targeting retirement at 60 needs £222,000 invested today — but the same person targeting retirement at 55 needs £283,000. Choosing to work 5 more years reduces the required Coast FIRE number by £61,000, simply because compounding has more time to work.

How the UK State Pension Lowers Your Coast FIRE Target

The full UK State Pension is worth £11,502 per year in 2025/26, paid from age 67, and rises with the triple lock. In portfolio terms, this income is equivalent to having an extra £287,550 invested at a 4% withdrawal rate — because £287,550 × 4% = £11,502.

This means your true required FIRE number is lower than the headline calculation suggests, particularly if you plan to retire close to 60. For someone spending £30,000/year, once the State Pension begins at 67, their portfolio only needs to generate £18,498/year — equivalent to a portfolio of just £462,450.

The practical implication: if you adjust your FIRE number downward to account for the State Pension (a reasonable approach for most UK FIRE planners), your Coast FIRE threshold also falls. A 38-year-old targeting an adjusted FIRE number of £462,450 instead of £750,000 reaches Coast FIRE at approximately £158,000 — considerably more achievable.

You can check your State Pension forecast and how many qualifying National Insurance years you have accumulated at gov.uk/check-state-pension.

What to Do Once You Reach Coast FIRE

Reaching Coast FIRE does not mean stopping work — it means stopping mandatory saving. The options that open up at this point depend entirely on your preferences:

• Continue as normal and reach full FIRE earlier. If you keep contributing, you are pulling your retirement date forward with every payment. Each additional year of saving at a high rate could reduce your time to full FI by more than a year.
• Shift to part-time or lower-paid work. Since you only need to cover living costs — not fund future retirement — you can take a lower-stress, lower-paid role and accept the trade-off. This is often called Barista FIRE, named after the idea of working a flexible job like a barista while your investments compound.
• Take a career break or sabbatical. If you have savings to cover your expenses for a period, Coast FIRE gives you the reassurance that your retirement is not damaged by a gap year or parental leave taken without employer contributions.
• Pivot to passion projects. Starting a small business, freelancing in an area you love, or focusing on creative work often generates less income — but at Coast FIRE, that is perfectly sustainable. You only need enough for today; tomorrow is already taken care of.

The key psychological shift at Coast FIRE is significant. You move from thinking “I must maximise my savings rate to stay on track” to “I can choose how I spend my time, as long as I cover my bills.” For many people, this shift in relationship with work — years before full retirement — is life-changing in itself.

Coast FIRE vs Full FIRE vs Barista FIRE

Coast FIRE and Barista FIRE often overlap in practice. Most people who reach Coast FIRE and continue in employment eventually shift toward lower-intensity work — effectively living Barista FIRE before they reach full FI.

Frequently Asked Questions

Work Out Your Coast FIRE Number

• UK Coast FIRE Calculator — enter your current portfolio, expected returns, and target retirement age to find your exact Coast FIRE number
• UK FIRE Number Calculator — calculate your full FIRE target first, including the State Pension adjustment
• UK Savings Rate Calculator — see how your current savings rate affects your timeline to both Coast FIRE and full FIRE
• All UK FIRE Calculators

This guide is for educational purposes only and does not constitute financial advice. Coast FIRE calculations use assumed investment returns — actual returns will vary and past performance does not guarantee future results. The State Pension figures quoted are for the 2025/26 tax year and may change. For advice specific to your circumstances, consult a qualified financial adviser regulated by the FCA.