FIRE Number Calculator
The pot you need before work becomes optional, how far along you are, and the age you get there at your current saving rate. All in today's money.
Your details
In today's money. Your actual current spending is the honest starting point, minus the mortgage if it will be gone.
ISAs, pensions, general investment accounts. Not your home, not your emergency fund.
Include employer pension contributions.
The full new State Pension is £12,548 a year. Counting it lowers the target, but only if you have 35 qualifying NI years.
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4% is the classic US-based figure. Many UK planners use 3% to 3.5% for a retirement longer than 30 years.
Global equities have averaged roughly 5% real over long periods. Use less to be safe.
Updates as you change the figures. No submit button needed.
Result
£750,000
is your FIRE number. At your current rate you reach it at 57, in 25 years.
8% of the way there
Where people get this wrong
The FIRE number is 25 times your spending, not 25 times your income. Most people plug in their salary and get a number twice as big as they need. The second mistake is the opposite: using 4% for a retirement that starts at 45 and might last 50 years, when that rule was tested on 30-year retirements. If you are aiming early, the honest move is 3.5% or lower, which pushes the target up by roughly a seventh.
How we calculate this
FIRE number = annual spending divided by the safe withdrawal rate. At 4% that is 25 times spending; at 3.5% it is about 28.6 times. The withdrawal rate comes from the Trinity study and William Bengen's work on US market history, which found a 4% initial withdrawal, rising with inflation, survived almost every 30-year period since 1926. UK returns have been lower on average, so many planners here use 3% to 3.5%.
Everything is in today's money. We grow your investments at the real return you set (nominal return minus inflation), add contributions monthly, and stop when the balance first reaches the target. If you count the State Pension, at each candidate retirement age we add a cash bridge for the pension income missing before 67, plus a withdrawal-rate pot for the remaining spending. We never require more than the target without State Pension. The displayed target corresponds to the projected retirement age (or the last modelled age if unreachable). Age 67 and the full pension are assumptions: check your own pension age and forecast. This is an approximation, not a cashflow plan.
Remember that most of a UK FIRE pot usually sits in a pension you cannot touch until 57. If you plan to stop work before that, the ISA and taxable portion has to bridge the gap on its own.
This tool is for general guidance only and is not financial or tax advice. Always check your own circumstances, ideally with a qualified adviser or accountant, before making decisions.
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