Build wealth · UK
FIRE Calculator
Work out your FIRE number from the spending you want to cover, then see how many years of saving it takes to get there from your current pot and monthly contributions.
Uses a real (after-inflation) return, so figures are in today's money. The 4% rule is a guideline, not a guarantee. An estimate to help you plan, not financial advice.
Your pot reaching the £750,000 you need to live on £30,000 a year at a 4.0% withdrawal rate.
How FIRE is worked out
Financial independence is the point where your pot is big enough that its returns can cover your spending for good. The common rule of thumb is the 4% rule: you need roughly 25 times your annual spending, because withdrawing about 4% a year has historically been sustainable. Decide what you would spend, multiply up to your FIRE number, then the question is how long your current pot and monthly saving take to get there.
Saving rate is the biggest lever. To see how a monthly amount grows on its own, try the compound interest calculator.
Common questions
What is FIRE?
FIRE stands for Financial Independence, Retire Early. The idea is to save and invest enough that the returns on your pot can cover your living costs, so paid work becomes optional. Financial independence is the milestone; retiring early is just one thing you can do once you reach it.
What is the 4% rule?
The 4% rule is a rough guide that says you can withdraw about 4% of your pot in the first year of retirement, then adjust for inflation, with a good chance it lasts 30 years or more. Turned around, it means you need roughly 25 times your annual spending. Lower the withdrawal rate for a bigger safety margin.
What return should I use?
This calculator uses a real return, meaning after inflation, so your FIRE number stays in today's money. A long-run real return of around 3% to 5% a year is a common assumption for a stock-heavy portfolio, but returns are not guaranteed and vary a lot year to year.
Does this include the State Pension?
No. It works purely from your own pot, so it is cautious. If you will also get the State Pension or a workplace pension from a certain age, your own savings may not need to cover everything for life, which can bring financial independence closer.
How can I reach FIRE sooner?
Three levers: save more each month, cut the spending your pot needs to cover (which also lowers your FIRE number), or earn a higher return, though chasing returns adds risk. Of these, your saving rate, the gap between what you earn and what you spend, usually matters most.
About this calculator
Works out your FIRE number from your spending and withdrawal rate, then projects your pot with standard compounding at a real (after-inflation) return, so everything is in today's money. The 4% rule is a widely used guideline, not a guarantee, and real returns vary. This is an estimate to help you plan, not financial advice. Last updated June 2026.