Coast FIRE calculator
Coast FIRE is the point where what you've already invested would grow to your FIRE number by retirement with no more saving. See the figure for today, whether you're past it, and the age you'd reach it if you keep saving.
Rules for tax year 2026/27Checked Free, no sign-up
Example figures
Change any to use yours
Your Coast FIRE number today
£267,941
Not yet: £117,941 short today. Saving £1,000 a month, you'd reach it at 48, around 2039.
- FIRE number
- £714,286
- Coast age
- 48
- Invested today
- £150,000
- Gap today
- −£117,941
Needed at 60: £25,000 over 3.5%
If £1,000 a month continues until then
- Your pot
- Coast FIRE number
Saving stops at 48
An illustration in today's pounds at a steady 4% real return; real returns vary year to year. Tax on withdrawals and the age pensions can be reached aren't modelled here; the full FIRE calculator covers both.
See your real FIRE date from your actual accounts in Aureli: your ISAs, pensions and savings in one place, with milestones for the number that matters.
See your FIRE dateHow this works
Your FIRE number is a year’s spending in retirement divided by the withdrawal rate: £25,000 at 3.5% is about £714,000. The Coast FIRE number is the amount that grows to that by your retirement age at the real return, with nothing more added. At 4% a year over 25 years, money grows about 2.67 times, so the Coast FIRE number at 35 for retiring at 60 is about £268,000.
If what you’ve invested today is at least that, you’ve reached Coast FIRE: from here, saving more brings retirement forward or makes it more comfortable, but isn’t needed to get there. If not, the calculator grows your pot month by month with your saving and finds the first whole age at which it meets the Coast FIRE number for that age, which rises each year as there’s less time left to grow. That is your coast age.
What this calculator assumes
- Everything is in today’s pounds, with a steady real return (after inflation and fees) every year. Real returns vary, so the result is an illustration, not a forecast.
- All your investments are one pot. It doesn’t split ISAs from pensions, so it doesn’t check that you can reach the money at your retirement age: a pension can’t be drawn before 57 for most people from April 2028.
- Tax on withdrawals isn’t counted. Pension income above the personal allowance is taxed, so a pension-heavy pot needs to be bigger than this shows.
- The State Pension isn’t added automatically. To count it, take it off the spending figure.
The FIRE calculator models all of this: an ISA bridge to pension access age, the State Pension from State Pension age and tax on pension income.
Why people use Coast FIRE
Full FIRE asks how much you need to stop work. Coast FIRE asks a smaller question: when could you stop saving for retirement and let time do the rest? Because of compounding, money invested in your 20s and 30s does far more work than money added in your 50s. At a 4% real return, £1 invested at 30 is worth about £3.24 at 60; £1 invested at 50 is worth about £1.48.
Reaching the coast point changes what extra saving is for. Some people keep saving to retire earlier; others use the room to work less, change career or spend more now. The calculator describes the numbers; the choice is yours.
What can move the line
Coast FIRE leans on decades of growth with nothing added, so it is sensitive to the return. A 3% real return instead of 4% over 25 years means needing about 27% more today. Markets also don’t deliver the average every year: a fall just before retirement, when the pot is largest, can leave it short of the FIRE number on the day it’s needed.
Spending can change too. A figure set in your 30s may not match the life you want at 60. Revisiting the inputs every year or so, with your real balances, keeps the number honest.
Questions
What is Coast FIRE?
Coast FIRE is having enough invested that, with no more contributions, it would grow to your FIRE number by your planned retirement age. You still work to cover today's spending, but you no longer need to save for retirement to get there.
How is the Coast FIRE number worked out?
Take your FIRE number (a year's spending over the withdrawal rate) and discount it back to today at the real return: FIRE number divided by (1 + return) to the power of the years to retirement. £714,000 needed in 25 years at a 4% real return is about £268,000 today.
What return should I use?
The calculator uses a real return, after inflation and fees, because the answer is in today's pounds. Shares have historically returned more than bonds or cash over long periods, but by different amounts in different decades and countries. Small changes compound a lot over decades, and trying a few rates shows how much the answer depends on this one.
Should I count the State Pension?
The calculator leaves the choice to you. The full new State Pension is £12,548 a year in 2026/27 and starts at State Pension age, which is later than most early retirement plans. Taking it off your spending lowers the Coast FIRE number, but only covers the years after it starts; the FIRE calculator models the gap before it.
What's the difference between Coast FIRE and Barista FIRE?
Coast FIRE stops saving for retirement but keeps working to pay today's bills. Barista FIRE stops full-time work and draws on the pot, with part-time income covering some of the spending. The FIRE calculator has a Barista option.
Does it matter whether the money is in an ISA or a pension?
For the Coast FIRE number itself, no: it treats everything as one pot. For retiring early it matters a lot, because a pension can't be reached before 57 for most people from 6 April 2028, and pension income is taxed while ISA withdrawals aren't.
Aureli
See your real FIRE date from your actual accounts
Aureli brings your ISAs, pensions, savings and debts into one place and keeps them valued daily. Set a milestone for your Coast FIRE number and model the rest in scenarios.
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