Financial independence calculator UK: your FIRE number

Financial independence calculator

Yearly spending to cover

What you want to spend each year without working, in today’s money, including any tax on what you take out.

Withdrawal rate

The share of the pot you take out each year. At 4% the target is 25 times what you take out; a lower rate is more cautious.

Savings and investments now

What you have already put aside for this goal: ISAs, other investments and savings accounts.

Monthly saving

What you put aside each month. The calculation assumes it rises with inflation.

Expected yearly return

The average yearly return you expect after fees and before inflation, for example 5.

Yearly inflation

The yearly rise in prices you expect, for example 2, the Bank of England’s target. Leave blank to ignore it.

Other income, age and target

Other yearly income without work

What will keep coming in from the day you stop work, such as net rent. A pension that only starts later does not count here.

Your age

Optional: to see the age at which you reach the target pot.

Target (in years)

Optional: in how many years you want to get there, to see the monthly saving it takes.

Target pot (your FI number)

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Enter your yearly spending and expected return to see your target pot.

Time to get there: —
Age at financial independence: —
Yearly withdrawal from the pot: —
Still to build up: —
Share of the target already saved: —
Real return (after inflation): —
Yearly saving: —
How long the pot lasts once you draw on it: —
Monthly saving to meet your target: —

Year-by-year projection

Enter your spending and expected return to see the projection.

Recent calculations

Nothing yet: copy, export or save a calculation to find it here.

How it works

Financial independence, the ‘FI’ in FIRE, is the point at which your investments can pay for your spending without you needing to work. Enter what you want to spend each year, a withdrawal rate, your savings and the return you expect: you get your target pot, the number of years to reach it, how long it then lasts and, if you set a target, the monthly saving it takes. Once you enter inflation, every amount is in today’s money.

Start from your spending, not your income

Your target depends on what you will spend, not on what you earn now. Count everything you expect to spend in a year without work: housing, food, transport, holidays, and any tax on what you take out of your investments. If some income carries on without work, such as net rent, enter it under ‘Other yearly income’: only the rest has to come from the pot.

Choose a withdrawal rate

The withdrawal rate is the share of the pot you take out each year. Your target is the yearly withdrawal divided by that rate: 25 times it at 4%, 28.57 times at 3.5%, 33.33 times at 3%. The lower the rate, the bigger the target and the better the pot’s chances of lasting. The calculator starts at 4%: it is only an assumption, to set as cautiously as you wish.

Return and inflation

Enter the average yearly return you expect from your investments after fees, then the inflation you expect. The calculator works out the real return, (1 + return) ÷ (1 + inflation) − 1, and works in today’s money: your monthly saving is assumed to rise with prices. With no inflation entered, the return is used as it is, which flatters the result if prices rise.

Reading the result

You get your target pot, the time it takes to reach it and, if you give your age, the age at which you get there. The calculator also shows how long the pot lasts once you start drawing on it, at a steady return: indefinitely if the real return covers the withdrawal rate, otherwise a number of years. With a target, it works out the monthly saving needed. The year-by-year projection exports as a CSV file.

Target pot = (yearly spending − other income) ÷ withdrawal rate, rounded to the penny.

Real return = (1 + return) ÷ (1 + inflation) − 1, rounded to 0.01 of a percentage point.

Each year: pot at year end = pot × (1 + real return) + 12 × monthly saving. The year’s growth is rounded to the nearest penny (halves away from zero), and the year’s saving is added at the end of the year, earning nothing that year.

The time to get there is the first year the pot reaches the target (100 years at most). The monthly saving needed is the smallest, to the penny, that reaches it within your target.

Example: £25,000 a year, £50,000 saved and £1,500 a month

At 4%, the target pot is £25,000.00 ÷ 4% = £625,000.00, 25 times your spending. With a 6% return and 2% inflation, the real return is (1.06 ÷ 1.02) − 1 = 3.92%. Adding 12 × £1,500.00 = £18,000.00 a year, the pot reaches £639,460.95 after 20 years: at 30 today, you get there at 50. To get there within 15 years you would need to save £2,243.94 a month. As the 4% withdrawal rate is only just above the 3.92% real return, the pot then shrinks very slowly: at a steady return it lasts more than 100 years.

Frequently asked questions

How do I work out my FIRE number?

Divide what you want to take out of your investments each year by your withdrawal rate. At 4% you need 25 times that amount: £30,000 a year needs £750,000. At 3.5% you need 28.57 times as much, £857,142.86. If some income carries on without work, such as net rent, take it off your spending first.

What withdrawal rate should I use?

It is an assumption, not a rule. As long as the real return on your investments matches or beats the withdrawal rate, the pot keeps its value; below that it wears down. At a steady 2% real return, taking out 4% a year empties the pot in 35 years; with no real return at all, in 25 years. The calculator assumes a steady return, but returns vary from year to year, and losses in the first years of withdrawals shrink the pot for every year that follows: a lower rate leaves a margin.

Should I allow for inflation?

Yes, if you want amounts in today’s money. A 6% return with 2% inflation only adds 3.92% of buying power a year. As a reference point, the Government has set the Bank of England an inflation target of 2%; actual inflation can be higher or lower.

What about tax?

The calculator leaves tax out, so add it to your yearly spending. It depends on where your money is. You pay no tax on interest on cash in an ISA, or on income or capital gains from investments in one, and in the 2026 to 2027 tax year you can put up to £20,000 into ISAs. You usually pay tax on income from pensions, including the State Pension, once your total income is above your Personal Allowance.

Can I count my pensions?

Only from when they start. You can usually only take money from a workplace or personal pension once you are 55, rising to 57 from 6 April 2028, and the State Pension only from your State Pension age, which depends on when you were born. The full new State Pension is £241.30 a week. If you stop work earlier, your pot has to pay for the years in between on its own, so leave those pensions out of ‘Other yearly income’: the result is then cautious, as they will later cut what you need to take out.

Financial independence calculator (FIRE)