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How this works
FIRE stands for financial independence, retire early. Your FIRE number is the pot you’d need to live off investments: your yearly spending divided by a safe withdrawal rate. At 4% that’s 25 times what you spend.
The calculator then grows what you’ve invested so far at the return after inflation, adds what you save each year (your take-home pay minus your spending), and finds when the pot reaches your number. It also shows your coast number, the amount that would grow to your FIRE number by a chosen age with nothing more added.
What it assumes
- Everything is in today’s money, and returns are smooth from year to year.
- Tax, fees and the State Pension aren’t included.
- The 4% rule comes from US data over 30-year retirements. Retiring earlier means a longer stretch, so a lower rate is safer.
Worked example
Age 30, spending £25,000 a year
- You take home £38,000 and spend £25,000, so you invest £13,000 a year. You have £30,000 invested already.
- At a 4% withdrawal rate your FIRE number is £625,000.
- With a 6% return and 3.1% inflation, the real return is about 2.8% a year. You’d reach your number in about 28.6 years, around age 58.
- Your coast number for age 60 is £271,934. Use a safer 3.5% withdrawal rate and the target rises to £714,286, about 31.4 years away.
Worked out with the same maths as the calculator above.
What to do next
Common questions
What withdrawal rate should I use?
4% is the usual starting point. If you plan to retire well before 60, many people use 3% to 3.5% to allow for a longer retirement and bad years in the markets.
Does the State Pension change my number?
Yes. The full new State Pension is £12,548 a year from State Pension age, which reduces what your pot needs to cover from then on. This calculator leaves it out, so its number is on the cautious side.
What matters most: income, spending or returns?
Spending, because it counts twice. Spending less means saving more each year and needing a smaller pot. Cutting £1,000 of yearly spending lowers your number by £25,000 at 4%.
Can I use my pension for FIRE?
Yes, but you usually can’t take it until 55, rising to 57 from April 2028. Many people use ISAs to bridge the gap between stopping work and that age.