Coast FIRE Calculator UK

What does Coast FIRE mean in the UK?

Coast FIRE means your pension pot and ISAs are already big enough to grow, without another penny from you, into what you’ll need when you retire. You keep working, but your salary only has to pay for the life you’re living now.

Take someone who’s 30, expects to spend £25,000 a year in retirement in today’s money, and plans to stop at 68, which is their State Pension age under current law. That’s 38 years of growth. With a 6% return, 2% inflation and a 4% withdrawal rate:

The calculator above starts with the left-hand column. The right-hand one is closer to reality for anyone who’ll end up with a full National Insurance record, and it roughly halves the target.

I use 6% rather than the 7% you’ll see on a lot of American sites. It leaves room for platform and fund fees, and for a portfolio that isn’t 100% shares.

How does the State Pension change the number?

The full new State Pension is £241.30 a week for 2026/27, or about £12,548 a year (GOV.UK). It’s uprated every April, so treating it as today’s money is a fair shortcut. You usually need 35 qualifying years on your National Insurance record for the full rate (more if you were contracted out before 2016), and at least 10 to get anything (eligibility rules).

The rough approach is simple. Subtract the State Pension you expect from your yearly spending, and put what’s left into the calculator as your spending figure. That’s how the right-hand column above was worked out.

How much to count is a judgement call. If you’re under 40, I’d count something like three-quarters of the full amount. Rules change, and a few years abroad or out of work can leave gaps in your record. Counting 75% in the example gives a Coast FIRE number of £90,355, still far below the £144,898 you get by ignoring it.

Then there’s the age itself. State Pension age is rising from 66 to 67 between 2026 and 2028, and under current law it goes to 68 between 2044 and 2046. Anyone born on or after 6 April 1978 gets it at 68 (timetable). A third State Pension age review is under way, so a 30-year-old should treat 68 as a current best guess. That’s why the calculator on this page defaults to 68.

What if you stop before State Pension age?

Subtracting the State Pension only works from the day it starts. If you stop at 60 and it doesn’t arrive until 68, your savings cover the full £25,000 for eight years.

One way to handle that is to add the missing State Pension for those years on top of the reduced FIRE number:

1. FIRE number counting the State Pension: £311,310.
2. Eight years of missing State Pension: £100,381.
3. Target at 60: £411,691.

With 30 years of growth from age 30, that’s a Coast FIRE number of £129,838, against £197,110 if you ignored the State Pension and retired at 60. It assumes the bridge money earns nothing above inflation, so it’s a little cautious. To reproduce it in the calculator, set retirement age to 60 and spending to £16,468, which is the reduced spending plus 4% of the bridge.

The other date that matters is when you can touch a private pension at all. The normal minimum pension age goes up from 55 to 57 on 6 April 2028 (GOV.UK). If you want the option of stopping before 57, the money for those years has to sit outside your pension.

Pension, SIPP or ISA?

For most employees the workplace pension comes first. The auto-enrolment minimum is 8% of qualifying earnings, with at least 3% from your employer (GOV.UK). Many employers pay more if you do, and free money from your employer is hard to beat. Contributions get tax relief, and the annual allowance of £60,000 caps how much you can pay in each year before extra tax charges kick in (annual allowance). Relief is also limited to what you earn.

A SIPP is a personal pension where you pick the investments yourself. Same tax relief, same access age. It makes sense if you’re self-employed, or if your workplace scheme’s funds are expensive and you’ve already taken the full employer match.

An ISA works the other way round. You can put in up to £20,000 a year across all your ISAs in 2026/27 (GOV.UK), with no tax relief going in, but everything comes out tax-free at any age. A stocks and shares ISA is the natural place for bridge money.

My rough rule: take the full employer match, then decide the split by how early you might want to stop. If you’re happy working to 60, lean on the pension. If you want the option of 50, you need a proper ISA balance too, because the pension will be locked until at least 57. Add both together for the calculator’s current savings figure.

What the calculator leaves out

Tax on the way out is the big one. You can usually take up to 25% of a pension tax-free, capped at £268,275 (lump sum allowance), and the rest is taxed as income. The State Pension is taxable too. The Personal Allowance is £12,570 in 2026/27, and a full State Pension of £12,548 uses almost all of it, so the taxable part of your private pension income will mostly be taxed at 20% or more (Income Tax rates). Either build that into your spending figure or keep part of your savings in ISAs.

Inflation is the next assumption to poke at. The Bank of England’s target is 2% (Bank of England), which is the default here, but inflation has run well above target in recent years. At 3% inflation the example’s Coast FIRE number rises from £144,898 to £209,929.

Sequence risk doesn’t show up at all. The calculator assumes the same average return every year. A crash in the first few years after you stop contributing does far more damage than one near the end, which is why most people who reach Coast FIRE keep paying something in, even if it’s just enough to keep the employer match.

The 4% withdrawal rate comes from US market history, as our methodology explains. UK returns haven’t followed the same path, so I’d also run the numbers at 3.5%. That moves the example from £144,898 to £165,598.

Finally, every figure here is in today’s pounds. You enter a normal, nominal return, and the calculator takes inflation off it. A £625,000 target means £625,000 of today’s buying power, not that number on a statement in 2064.