Coast FIRE calculator
Find the point where compounding takes over and saving becomes optional. There's a point where you can stop adding and still land fine. Most people walk past it without noticing.
Updated for the 2026/27 tax year · reviewed
Your Coast FIRE plan
Your Coast FIRE number today
£323,975
The pot that would grow to your £750,000 FIRE number by age 60 with no further saving. You're £223,975 short of it today - but at your current £1,500 a month you reach it at age 52.
FIRE number
£750,000
£30,000 ÷ 4.0% SWR
Coast age
52
keeping up monthly investing
Gap today
£223,975
vs the coast number
Years to retirement
25
age 35 to 60
When does compounding take over?
The dashed line is the pot you'd need at each age to coast from there; the green line is your projected pot. Where they cross, saving becomes optional. All in today's money.
Coasting is a bet on the next twenty years. Track it.
The coast number assumes steady growth and no surprises. Quidworth projects your real pots - pension, ISA and the mortgage alongside - so you can check the bet is still on course every year.
Create your free accountHow this calculator works
Your FIRE number is annual spending divided by your safe withdrawal rate - at the default 4% that's the familiar 25× rule. Coast FIRE asks a gentler question than full FIRE: not “when can I stop working?” but “when can I stop saving?”. The coast number at any age is the FIRE number discounted back from your retirement age at your assumed growth rate net of inflation - the pot that, left alone, compounds into the full amount by the time you retire.
Everything is kept in today's money, which is why the discounting uses real growth (growth net of inflation, compounded properly rather than subtracted). A pot that only keeps pace with inflation buys no more retirement than it does today, so only the growth above inflation counts towards coasting. The chart shows the coast requirement falling as you age - less time left to compound means more is needed - while your projected pot rises; the crossing point is your coast age.
Two UK cautions before acting on it. Most of a typical pot sits in a pension, locked until 55 today and 57 from April 2028, so coasting into an early retirement needs enough outside the pension to bridge the gap. And stopping pension contributions usually means giving up employer contributions and tax relief - money that costs you nothing - so many people at Coast FIRE keep contributing anyway and treat the milestone as freedom to take career risks, not an instruction to stop saving.
Questions people ask
What is Coast FIRE?
Coast FIRE is the point where your invested pot is already big enough to grow into your full FIRE number by retirement age with no further contributions - from there you only need to earn enough to cover your living costs, and compounding does the rest. It's a milestone on the way to full financial independence, not early retirement itself.
How is the Coast FIRE number calculated?
Your FIRE number (annual spending ÷ safe withdrawal rate) is discounted back from your retirement age to today at your assumed growth rate net of inflation. At 5% real growth, needing £500,000 at 60 means having about £151,000 at 35 - that's the coast number, and it falls every year you wait because there's less time left to compound.
Why use growth net of inflation?
Because your FIRE number is set in today's money - it's today's spending times 25. A pot that merely grows with inflation buys no more retirement than it does now, so only growth above inflation moves you towards the target. Using real returns keeps the whole calculation honest in today's purchasing power.
Are there UK-specific catches with coasting?
Yes - if most of your pot is in a pension, it's locked until age 55 today, rising to 57 from April 2028, so coasting to an earlier retirement needs enough outside a pension to bridge the gap. Stopping pension contributions also usually means giving up employer contributions and tax relief, which is free money most people shouldn't leave behind just because a spreadsheet says they can.
Last reviewed against 2026/27 UK rules. Projections are estimates for education, not financial advice. Understanding your projections.
A calculator answers one question at a time.
The planner keeps all of them next to each other, so an overpayment you model today still shows up in the pension picture in twenty years.
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- Your figures carry over