FIRE Calculator

When Can You Retire?

Financial Independence Retire Early. Find your FIRE number — the pot you need to cover your retirement spending — and see how many years it takes to get there. Includes UK State Pension and the 4% safe withdrawal rule.

By UK Tax Drag · Reviewed 26 September 2026

Years to financial independence at your savings rate.

Financial Independence Retire Early (FIRE) is the simple maths of "what savings rate, at what return, builds a pot that sustains my desired annual spending forever?"

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More about this calculator

The classic 25× rule says a pot of 25× your annual expenses supports withdrawing 4% a year; it is a rule of thumb drawn from historical US market returns, not a guarantee.

For UK FIRE the key adjustments are: return assumptions that may be lower than the US history behind the 4% rule, the State Pension from State Pension age (between 66 and 68 under current law, depending on date of birth), and tax wrappers (after tax relief, a £1 pension contribution costs 80p of take-home pay for a basic-rate taxpayer and 60p for a higher-rate taxpayer who claims the extra relief, before tax on withdrawal). This calculator takes the first two as inputs (real returns before and after FIRE, and a State Pension amount and age); it does not model tax relief, tax on withdrawals or which wrapper holds the money.

Educational only. Returns assume constant annual real (inflation-adjusted) growth. Actual returns are volatile. State Pension projections are today's money. Not financial advice.

What is FIRE?

Financial Independence Retire Early (FIRE) is achieving a net worth large enough that your investment returns alone can cover your living costs forever. The traditional benchmark is 25 times your annual spending — which equates to the famous 4% safe withdrawal rate. In the UK, the State Pension cushions later years, so your investment pot only needs to bridge the gap until age 67 or later.

Your inputs

Current age

1870

Target FIRE age

3075

Current investments (£)

£0£2m

Monthly savings now (£)

£0£10k

Annual spend (retirement) (£)

£10k£200k

Real return pre-FIRE (%)

0%10%

Real return post-FIRE (%)

0%8%

Safe withdrawal rate (%)

2.5%5%

State Pension (age 67+) (£/yr)

£0£15k

State Pension age

5575

Inflation assumption (% — for reference)

0%6%

Your FIRE number

£0

investable pot needed

Current pot

£0

Projected at target age

£0

£0FIRE pot target

0Years to FIRE

0%Current savings rate

0xYears of spending covered

Target gapWaiting for a FIRE gap estimate.

Bridge to State PensionWaiting for bridge-fund detail.

Best next leverSavings rate, target spending and wrapper mix matter more than tiny return tweaks.

What this means

The professional use of a FIRE estimate is to separate three jobs: the bridge before State Pension age, the long-run withdrawal rate after that, and the wrapper mix that funds both without unnecessary tax drag.

Professional read

How to read the FIRE result properly

A serious FIRE plan is not one pot and one withdrawal rate. It is a sequence problem, a wrapper problem, and a spending-discipline problem all at once.

Key assumptionsThis model assumes smooth long-run returns, the contribution pattern you entered, and a steady spending target rather than real-world lumpy withdrawals.

Common mistakeUsing a FIRE number as if it automatically solves the bridge before State Pension age or the wrapper mix needed to fund that bridge tax-efficiently.

Best next actionStress-test the spending target, then compare the bridge years separately from the post-State-Pension years before treating the headline number as a decision point.

When this breaks downSequence risk, market valuation, one-off spending shocks, and pension access timing can all make a simple FIRE multiple look cleaner than reality.

Professional note. The most useful improvement after a FIRE result is usually not a higher assumed return. It is a better savings rate, a tighter spending plan, or a cleaner wrapper strategy.

Pot trajectory to FIRE and beyond

Projected pot growth FIRE number target State Pension age

Year-by-year projection

This table shows your pot accumulation until FIRE age, then drawdown in retirement. Notice how State Pension arrival reduces the annual withdrawal needed.

Age	Year start pot	Contribution	Growth	Withdrawal	Year end pot

Your savings rate is the biggest lever

Starting from nothing, the share of take-home pay saved — not the absolute amount — sets the time to FIRE, because a higher savings rate means both more going in and a lower spending target. The table shows the years needed to build a pot of 25 times annual spending (a 4% withdrawal rate), starting from zero, with savings added at the end of each year and an illustrative 5% real return. At those assumptions a 40% savings rate takes well under half as long as 10%: about 22 years against 51.

Savings rate	Years to FIRE	Example: £30k spend
10%	51.4	Save £3.3k/yr
20%	36.7	Save £7.5k/yr
30%	28.0	Save £12.9k/yr
40%	21.6	Save £20k/yr
50%	16.6	Save £30k/yr
60%	12.4	Save £45k/yr
70%	8.8	Save £70k/yr

Types of FIRE

These labels come from the FIRE community; the spending levels are loose conventions rather than fixed definitions.

Lean FIRE: £15-20k annual spend. Minimalist lifestyle, maximum flexibility.
Regular FIRE: £25-40k annual spend. Comfortable but not extravagant.
Fat FIRE: £50k+ annual spend. More luxuries, same financial independence principle.
Coast FIRE: contributions stop once the pot is expected to grow to enough by traditional retirement age (67+) without adding anything more.
Barista FIRE: part-time work covers living costs while the investments are left to grow.

The Trinity Study and the 4% rule

The "4% rule" comes from US research in the 1990s, including William Bengen's 1994 paper and a 1998 study by three professors at Trinity University in Texas (the "Trinity study"). They tested how often withdrawing a set share of a starting pot, raised with inflation each year, would have lasted through past periods of up to 30 years of US share and bond returns. The results depend on the period, the mix of shares and bonds and the length of retirement, and past US returns may not be repeated, so the safe withdrawal rate here is an input. Its default is 3.5%, below 4%.

Flexible spending

The calculator withdraws the same real amount every year. Some withdrawal approaches cut spending after poor years and allow more after good ones, which changes how long a pot lasts. Changing the safe withdrawal rate above shows how sensitive the FIRE number is to that assumption.

UK-specific FIRE considerations

Bridge fund (pre-State Pension): Your pension pots (SIPP, workplace) are locked until 55/57, so you need a bridge in a General Investment Account or ISA to cover spending from FIRE age to State Pension age. This table shows a rough breakdown:

Investment type	Use case	Withdraw from
Lifetime ISA	Bridge fund + retirement top-up (£4k/yr cap + 25% govt bonus)	Age 60+ or first home
Stocks & Shares ISA	Bridge fund (tax-free growth, no CGT on withdrawal)	Any age
General Investment Account	Overflow bridge, post-ISA allowance	Any age (CGT applies, ~£3k exemption/year)
SIPP (personal pension)	Main wealth-building wrapper (tax relief going in, 25% tax-free lump sum)	Age 55+ (rising to 57)
Workplace pension	Employee + employer contributions, often locked until 55+	Age 55+ (rising to 57)

Sequence-of-returns risk

A large market fall in the first few years of retirement, while withdrawals are being taken, can leave a pot permanently smaller even if long-term average returns turn out as assumed. The calculator uses the same return every year, so it does not show this. Holding some years of spending in cash, or moving gradually from shares towards bonds around the FIRE date, are ways people try to reduce the risk; each has its own costs.

Compound interest calculator · Pension calculator · ISA vs GIA tax comparison · Salary sacrifice calculator

Official references & background reading

Bogleheads — Trinity Study (original 4% rule research) MoneyHelper — UK Pension freedoms and withdrawals FCA — Financial Conduct Authority guidance GOV.UK — State Pension eligibility and rates

Pensions guidePension calculators, contribution rules, drawdown comparisons and State Pension forecasts for 2026/27.

About this calculator

Last reviewed: September 2026. Reviewed by the Editor against current official guidance for 2026/27.

Verified against: FCA InvestSmart — investing basics (checked on the last review date above).

Source: calculator JavaScript is unminified at /assets/ — see Open methodology for how to verify the math. Updates tracked in the changelog.

Spotted an error? Report it. Confirmed errors are corrected under the corrections policy.

Disclaimer: This tool gives a guideline estimate using current published UK rates and thresholds. It is general information, not personal financial, tax, or legal advice. Verify the figures against your own circumstances, the latest gov.uk guidance, and a qualified adviser before acting. UK Tax Drag accepts no liability for decisions made on the basis of these calculations.

▸ How this calculator works — formulas, rates and assumptions

The core formula

FIRE number = bridge + post-State-Pension pot. Bridge = years from FIRE age to State Pension age × annual spend (no growth assumed). Post-State-Pension pot = (annual spend − State Pension) ÷ safe withdrawal rate. The projection grows the current pot at the pre-FIRE real return, adding 12 × the monthly savings each year until FIRE age; from FIRE age it withdraws the full spend until State Pension age and the spend minus the State Pension after that, with growth at the post-FIRE real return.

What each input means

Current age and target FIRE age	Set the number of years of saving.
Current investments	The pot available now, in today's money.
Monthly savings	Added as 12 × the monthly figure each year until FIRE age.
Annual spend in retirement	In today's money, the same every year.
Real returns before and after FIRE	After-inflation returns; assumptions, not guaranteed returns.
Safe withdrawal rate	Sets the pot needed after State Pension age; the default is 3.5%.
State Pension and State Pension age	The annual amount in today's money (the default is the full new State Pension, about £12,548 a year in 2026/27) and the age it starts.
Inflation	For reference only; it does not change the result, because every figure is in today's money.

2026/27 rates and thresholds used

Full new State Pension 2026/27	£241.30 a week (£12,547.60 a year)
Withdrawal rate	The 4% figure comes from US historical studies (Bengen 1994; the Trinity study, 1998); it is an assumption, not a guaranteed sustainable rate
UK ISA allowance	£20,000/year (tax-free wrapper)
UK pension AA	£60,000/year (tax relief at marginal rate)

Key assumptions

The real returns entered are constant; actual returns vary from year to year and are not guaranteed.
Spending is the same in real terms every year, and the bridge years are costed as spend × years with no investment growth.
The drawdown projection runs for 40 years from FIRE age.
No tax is modelled on contributions, growth or withdrawals, and all the money is treated as one pot.

Known limitations / edge cases

The 4% rule was derived from US market history; other countries and periods give different results.
Sequence-of-returns risk: a bad first decade can break the maths even if long-run returns are OK.
Doesn't model healthcare costs explicitly — UK NHS makes this easier than US but private care + care home costs can be significant.
Doesn't model pension access: private pensions can normally be taken from 55, rising to 57 from 6 April 2028, so money needed before then has to be held outside a pension.

The calculator code is reviewed against current HMRC, FCA and MoneyHelper guidance on every page review (see the "Last reviewed" date above). Found an error? Report it via the contact form.

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Pages are checked against the primary sources listed on each page and reviewed by the Editor; corrections are logged in the changelog. Pages are drafted with the help of AI tools (how AI is used). No affiliate revenue. No sponsored content. No paid placements.

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UK Tax Drag is an independent publication by Finsolve Consulting Limited, not affiliated with or endorsed by HMRC, GOV.UK or any government body.

When Can You Retire?

What is FIRE?

Your inputs

What this means

How to read the FIRE result properly

Year-by-year projection

Your savings rate is the biggest lever

Types of FIRE

The Trinity Study and the 4% rule

UK-specific FIRE considerations

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