FIRE calculator
The pot your income needs, the year it arrives, and the part of it you would not be allowed to spend yet — with the withdrawal rate as your assumption rather than this page’s.
Calculator
Only used to turn a number of years into an age, so the answer reads as a date rather than a duration.
In today's money, before tax. This is the figure the whole plan is sized on: an ISA pays it with no income tax, a pension does not, and the panel below prices both.
Your assumption, not a law. The number below is your income divided by this rate, so 4% is the same statement as "25 times spending". Zero is not a rate this can use — a rate of nothing needs a pot of everything — so clearing the box gives 0.1%.
ISAs, general investment accounts, cash. Anything you could draw on tomorrow without waiting for a birthday.
Defined contribution pensions — workplace and personal. A defined benefit (final salary) pension is not this and is not modelled here.
Paid in monthly, at the end of each month.
Everything that reaches the pension: your contribution, your employer's, and the tax relief added to it.
The accessible side has a speed limit. Up to £20,000 a year can go into ISAs in 2026/27, across all types. Anything above it can still be invested, in a general investment account, where the dividends and the gains are taxable — which this page does not model. The ISA calculator splits the limit across the four types.
A real return — what you assume the pot grows by above inflation. Everything on this page is in today's money, so entering a nominal return overstates every figure below. It is your assumption and this page has no market data to check it against.
Charged on the value of the pot and deducted from it. A fund's own ongoing charge is taken inside the fund and is not this — model it by reducing the growth assumption above.
The normal minimum pension age. This page does not assert one: it is not in the tax engine, it has already been legislated to rise, and some older schemes carry a protected age. Check yours and enter it.
The term the largest-income figure below is worked out over. The 4% rule was measured over 30 years; stopping work at 45 is a longer retirement than that, and the two are not interchangeable.
Rent, a part-time salary, a defined benefit pension, a state pension once it starts. Taxable pension income stacks on top of it, so leaving this at £0 shows the tax of someone with nothing else coming in.
Income tax on a pension withdrawal is devolved, so a Scottish taxpayer meets a different set of bands.
Contributions are treated as monthly, at the end of each month; growth and the charge are applied on the same cycle. The investment calculator is where those conventions are choices. Income tax figures are 2026/27 rates on the income you entered. No National Insurance is charged on a pension withdrawal, and none is shown. Every calculation runs in this tab: there is no application server and no database, so nothing you type is transmitted or stored. A share link is the exception — it carries your figures in the URL. What that means.
Your number, the year you reach it, and the years you cannot touch the pension
The number
| Income you want the pot to pay, a year | £30,000.00 |
|---|---|
| Withdrawal rate you assumed | 4.00% |
| Which is 25.0× your annual income | £750,000.00 |
The 4% rule is a result, not a law — and it is not a British one. It comes from the Trinity study, which tested withdrawal rates against United States stock and bond returns over 30-year retirements. It is a measurement of one market over one horizon, and this site has no market data of its own to check it or replace it with. That is why the rate is a box you can change rather than a constant, and why the figure above moves the moment you change it: a lower rate is a bigger pot, and nothing on this page can tell you which rate is right.
When the pot gets there
This half of the page is arithmetic, not a forecast. It is what would happen if the pot grew at exactly 5% above inflation every single month for 18 years, which nothing does. Real returns arrive in an order, and the order changes the answer. There is no statutory figure in this part of the calculation and nothing here has been checked against gov.uk, because a growth assumption is not the sort of thing an authority could confirm.
On these assumptions the pot reaches £750,000.00 in 18 years, when you are 48.
| The pot at that point | £767,963.27 |
|---|---|
| Of which you could actually draw on at 48 | £146,689.74 |
| Locked in a pension until 57 | £621,273.53 |
| Paid in over those 18 years | £359,998.56 |
| Growth over the term, after the charge | £335,173.89 |
| Charges deducted from the pot | −£17,209.18 |
| Age | Opening | Paid in | Growth | Charges | Closing |
|---|---|---|---|---|---|
| 31 | £90,000 | £20,000 | £4,949 | −£254 | £114,695 |
| 32 | £114,695 | £20,000 | £6,182 | −£317 | £140,559 |
| 33 | £140,559 | £20,000 | £7,474 | −£384 | £167,649 |
| 34 | £167,649 | £20,000 | £8,827 | −£453 | £196,023 |
| 35 | £196,023 | £20,000 | £10,244 | −£526 | £225,740 |
| 36 | £225,740 | £20,000 | £11,728 | −£602 | £256,866 |
| 37 | £256,866 | £20,000 | £13,282 | −£682 | £289,467 |
| 38 | £289,467 | £20,000 | £14,911 | −£766 | £323,611 |
| 39 | £323,611 | £20,000 | £16,616 | −£853 | £359,374 |
| 40 | £359,374 | £20,000 | £18,402 | −£945 | £396,831 |
| 41 | £396,831 | £20,000 | £20,273 | −£1,041 | £436,063 |
| 42 | £436,063 | £20,000 | £22,232 | −£1,141 | £477,153 |
| 43 | £477,153 | £20,000 | £24,284 | −£1,247 | £520,190 |
| 44 | £520,190 | £20,000 | £26,433 | −£1,357 | £565,266 |
| 45 | £565,266 | £20,000 | £28,685 | −£1,473 | £612,478 |
| 46 | £612,478 | £20,000 | £31,043 | −£1,594 | £661,927 |
| 47 | £661,927 | £20,000 | £33,512 | −£1,721 | £713,718 |
| 48 | £713,718 | £20,000 | £36,099 | −£1,853 | £767,963 |
The bit the American calculators leave out: the bridge
You reach the number at 48 and you cannot touch the pension until 57. That is 9 years that have to be paid for out of the £146,689.74 sitting outside a pension. A pot being big enough and a pot being reachable are different statements, and this is the one almost no FIRE calculator makes, because the calculators are American and America has no equivalent lock.
| Years to bridge | 9 |
|---|---|
| Accessible pot when you stop | £146,689.74 |
| Accessible pot that would pay £30,000 a year in full for all 9 | £220,392.38 |
| Paid out of it over the gap | £166,683.35 |
The accessible side runs out in year 6 of 9. The pot is big enough and you still could not stop, because £621,273.53 of it is behind an age. You would need £73,702.64 more outside a pension by then. Moving money from the pension side to the accessible side is not a free fix — it gives up the tax relief going in — which is what makes this a genuine trade rather than an oversight.
What the pot actually supports, at your own assumptions
| Income your withdrawal rate assumes | £30,000.00 |
|---|---|
| Largest level income this pot pays in full, every month, for 30 years | £47,452 |
| Which is this share of the pot | 6.18% |
The second figure is almost always the larger, and the gap is not free money. A constant-rate schedule cannot run out early because of a bad decade, and a real one can: the order returns arrive in is the whole difference between the two, and it matters most in the first few years of drawing, when a fall sells more of the pot to pay the same income. A withdrawal rate is an attempt to survive that order; this arithmetic contains no order at all. Neither figure is a rate this page recommends, neither has been judged prudent by anyone, and changing the growth assumption changes the second one immediately. What neither knows is how long you will live, what returns will do or in what sequence, or what your income will have to buy by then.
What that income costs in tax, and where it comes from
| Drawn from | Income tax | Left to spend |
|---|---|---|
| An ISA | £0.00 | £30,000.00 |
| A pension, as taxable drawdown | £3,486.00 | £26,514.00 |
An ISA withdrawal is not income. It does not appear on a tax return, it does not use your personal allowance, and it does not push anything else into a higher band — which is why the first row is a real zero rather than an omission. Taxable pension income does all three, and it stacks on whatever else you receive that year, so the second row is the tax of somebody with no other taxable income at all — put a figure in the other-income box and it rises. The number at the top of this page is sized on income before tax, so a plan funded from a pension buys less than the same plan funded from an ISA.
Two things this section deliberately does not do. It does not spread the 25.00% of a pension that can normally be taken free of income tax across the drawdown, so the pension row is the tax on drawing the whole income as taxable — the drawdown calculator takes the lump sum first and prices what is left. And it uses 2026/27 thresholds against money in today’s terms: income tax thresholds are not linked to prices, so a plan that arrives in twenty years meets whatever the thresholds are then, which nobody can tell you now.
Worked example: reaching the number, and still not being able to stop
These are the figures the calculator above loads with, so every number in this section can be checked against it without typing anything. Someone aged 30 who wants the pot to pay £30,000.00 a year, dividing by a 4.00% withdrawal rate, with £15,000.00 they can reach and £75,000.00 they cannot, paying in £4,000.00 a year to the first and £16,000.00 a year to the second, at 5% a year above inflation after a 0.25% charge.
| The number (25.0× the income) | £750,000.00 |
|---|---|
| Years to reach it | 18 |
| Age when the pot gets there | 48 |
| Accessible at that age | £146,689.74 |
| Locked in a pension until 57 | £621,273.53 |
| Accessible pot that would cover the 9 years in between | £220,392.38 |
| Income tax if that income comes out of a pension | £3,486.00 |
Three things in that table are worth pausing on.
- The pot arrives years before it can be spent. At 48 the total clears £750,000.00 and £621,273.53 of it is behind an age. This is the ordinary shape of a UK plan rather than a badly-chosen example: auto-enrolment and salary sacrifice put most people’s money into the wrapper they cannot reach first, because that is the wrapper the tax relief is in.
- The gap is 9 years, and it has to be paid for out of £146,689.74. On these figures it does not: the accessible side runs out in year 6. The plan is not short of money, it is short of money it is allowed to touch, and no calculator that models one pot can tell you that.
- The number is sized on income before tax. £30,000.00 drawn from an ISA is £30,000.00 to spend. The same figure drawn as taxable pension income costs £3,486.00 and leaves £26,514.00. Two plans with the same pot are not the same plan.
Methodology and sources
Three claims, and which is which
This page is three calculations joined at one figure. The number is your income divided by a withdrawal rate you chose. The date is a projection of two pots at a growth rate you chose. The tax is income tax at published rates. They rest on different kinds of claim, they are computed by different code, and the rest of this section keeps them apart on purpose.
The number, and whose result the 4% is
The pot required is annual income ÷ withdrawal rate, which at 4.00% is the same statement as “25 times your spending”. The multiple is not written down anywhere in this calculator — it is 100 ÷ rate, so changing the rate changes it.
The rate is an assumption, and the familiar one comes from somewhere specific. The 4% figure is the Trinity study’s result: withdrawal rates tested against United States stock and bond returns over 30-year retirements. It is a measurement of one market over one horizon. It is not a UK figure, it is not a rule of arithmetic, and it says nothing about a retirement that starts at forty-five and has to last fifty years. This site holds no market data of any kind, so it cannot confirm that rate, improve on it, or offer you a better one — which is exactly why it is a box rather than a constant, and why the panel above puts the arithmetic of your own growth assumption next to it.
The date, period by period
There is one loop and it is the only place money moves. For each month: add the contribution at the end of the month, apply the month’s growth, deduct the platform charge. Every figure is a whole number of pence and every row satisfies opening + paid in + growth − charges = closing exactly, so the headline cannot disagree with the schedule it was read off. The year the pot first reaches the target is found by scanning the year-ends of one long schedule, not by rearranging a formula.
Everything is in today’s money, so the growth rate is a real return. A withdrawal rate is a real rate and spending is stated in today’s terms, so mixing a nominal growth assumption into the comparison would not be a rounding problem — it would put two different sorts of pound on the same line. Enter what you assume the pot returns above inflation. The cost of that choice is stated rather than hidden: income tax thresholds are not linked to prices, so the tax figures are today’s thresholds against today’s money.
There is no statutory figure anywhere in this half of the calculation, and a fixed-rate projection is not a forecast. The growth rate, the charge and the contributions are yours, and there is nothing in them an authority could confirm. So this part carries no gov.uk verification claim and will not borrow one from the tax half below. Nothing grows at the same rate every month; real returns arrive in an order, and the order changes the outcome — which is the difference between the largest income this arithmetic supports and the smaller one a withdrawal rate is trying to survive.
The bridge: why a UK plan needs two pots and an American one does not
A defined contribution pension cannot be touched until the normal minimum pension age. An ISA can be touched at any age. So “the pot is big enough” and “I can stop working” are different statements in the UK, and the distance between them is the thing this page models that almost nothing else does.
The two pots are therefore projected as two pots. When the combined total reaches the number, the page reads the accessible side off its own schedule, works out how many years stand between that age and the access age you entered, and runs those years as a drawdown from the accessible pot alone — so the answer accounts for the growth the bridge earns while it is being spent and the charge taken from it, neither of which “income × years” does. It then solves for the accessible pot that would pay the income in full for the whole gap, by re-running the same projection rather than by discounting the target, and reports the difference.
The access age is a field, and this page does not assert one. No age of any kind is in the tax engine behind this site, the normal minimum pension age has already been legislated to rise, and some older schemes carry a protected age of their own. A calculator that typed a number in would be publishing an unverified figure that looks statutory. Check yours and enter it — and note that a plan built on today’s access age is exposed to it moving, which is a risk this arithmetic cannot price.
The tax, and which wrapper the income comes from
Taxable pension income is earned income in the year it is withdrawn: it is added to your other income and taxed at whatever rate that income has already taken you to, rather than starting again at the personal allowance. An ISA withdrawal is not income at all. So the same figure costs different amounts depending on where it comes from, and both figures are measured — the bill with the income, less the bill without it — rather than derived from a rate.
Normally 25.00% of a defined contribution pension can be taken free of income tax. This page does not spread that across the drawdown, so its pension row is the tax on drawing the whole income as taxable — the higher of the two readings. The drawdown calculator takes the lump sum out first and prices the income from what is left. No National Insurance is charged on a pension withdrawal, at any age, so none is shown.
Up to £20,000 a year can be put into ISAs in 2026/27, across all types, which is a real constraint on how fast the accessible side can be built — and the reason a plan can be short of reachable money while being ahead on the total. The ISA calculator splits that limit across the four types.
Where the tax figures come from
- gov.uk — Income tax rates and allowances: current and past
- gov.uk — Tax when you get a pension
- gov.uk — Individual Savings Accounts
- gov.scot — Scottish income tax rates and bands
The income tax rates, thresholds and allowances this page calculates with — and the ISA subscription limit — were verified against gov.uk on 12 August 2026. That check covers the published figures used by the tax half of this page and nothing else. It does not verify any figure the page produces, and it does not reach the projection or the withdrawal rate at all: a growth assumption, a contribution and a rate taken from an American study have no published source to be checked against. The check was carried out automatically and no named person has signed it off. Check anything that matters against gov.uk, or with an accountant or a regulated adviser.
What this calculator does not model
- Any sequence of returns. One rate, every month. That is the single biggest difference between this arithmetic and a retirement, and it is why the largest income the schedule supports is larger than any withdrawal rate anybody proposes.
- The state pension. No age, no amount, no forecast. It changes a real plan considerably and it is not on this page; put it in the other-income box yourself if you want the tax figure to include it.
- Tax on the accessible pot while it is being built. Money above the ISA limit goes into a general investment account, where dividends and gains are taxable. This page treats the accessible side as untaxed throughout, which flatters it. Dividend tax and capital gains tax price that separately.
- The lump sum allowance, the money purchase annual allowance, the annual allowance and its taper, defined benefit pensions, and emergency tax on a first withdrawal.
- Anything about you. No life expectancy, no health, no partner, no property, no care costs, no redundancy and no children. This is information, not advice: it does not recommend a rate, an amount, a wrapper, a product or a provider, and no figure on it is a personal recommendation.
Nothing you type here is transmitted or stored — there is no application server and no database. A share link is the exception: it carries your figures in the URL, and opening one is an ordinary request that carries them to the host. What that means.
Financial independence questions
- How much do I need to retire early in the UK?
The arithmetic everyone uses is your annual income divided by a withdrawal rate — at 4.00% that is 25 times what you want to spend, so £30,000.00 a year needs £750,000.00. The rate is an assumption and the calculator lets you change it, because the familiar 4% comes from a study of United States markets over 30-year retirements rather than from anything about the UK. The bigger UK-specific point is that the total is not the whole answer: money inside a pension cannot be touched until the normal minimum pension age, so a plan to stop working before then needs enough outside a pension to live on in the meantime.
- Is the 4% rule reliable in the UK?
It is not a UK figure. The 4% rule is the Trinity study’s result, measured against United States stock and bond returns over 30-year retirements, and it has been applied to British plans by borrowing rather than by measurement. It also assumes a 30-year retirement: someone stopping work at forty-five is planning for far longer than that, which is a different question the study did not ask. This site holds no market data and cannot tell you what rate to use — what it can do is show you what any rate you pick does to the size of the pot, and what income your own growth assumption would actually support over the term you set.
- Can I retire before I can access my pension?
Only if you have enough outside the pension to live on until you get there. This is the constraint that separates a UK plan from an American one, and it is why the calculator asks for two pots rather than one. It works out the year the combined pot reaches your number, how much of that is accessible at the time, how many years stand between that age and the access age you entered, and whether the accessible side pays your income in full for all of them — then solves for the accessible pot that would. The access age is a field rather than a figure this page asserts: it is not in the tax engine, it has already been legislated to rise, and some older schemes carry a protected age.
- Does my pension count towards my FIRE number?
Towards the number, yes — it is your money and it compounds like any other. Towards retiring early, only from the access age onwards. Treating the two pots as one total is exactly the mistake this page is built to expose: a plan can be comfortably ahead on the total and still unable to start, because the part you are allowed to spend is too small to cover the years in between. The panel above shows both figures side by side for that reason.
- Should I put more into an ISA or a pension for FIRE?
This page will not answer that, and no calculator honestly can — it is a trade between tax relief going in, tax charged on the way out, and access, and the right side of it depends on your marginal rate now, your income in retirement, and when you want to stop. What the calculator can do is price the access side of it: it shows the years you would have to bridge and the accessible pot that would cover them, so you can see what moving money between the two costs and buys. A decision that matters is worth taking to a regulated financial adviser, and Pension Wise is the free government guidance service for the pension half of it.
- Are these figures in today’s money?
Yes, and that is why the growth box asks for a return after inflation rather than a headline one. Spending is stated in today’s terms and a withdrawal rate is a real rate, so a nominal growth assumption would put two different sorts of pound in the same comparison and make the pot look far better than it is. The one place it leaks is tax: income tax thresholds are not linked to prices, so the tax figures apply today’s thresholds to today’s money, and a plan arriving in twenty years meets whatever the thresholds are then.
- What if the calculator says I never get there?
Then it says so, with the shortfall, rather than showing a blank or a very large number. Not reaching the target inside the term searched is a finding about the plan and it is reported as one: the pot after the full term, and how far short of the number that leaves you. The three things that move it are the income you are sizing the pot on, the rate you are dividing by, and what goes in each month — and the first two change the target itself, which is usually the larger effect.
- How much tax will I pay on my FIRE income?
It depends entirely on which wrapper it comes out of, which is the part most FIRE arithmetic skips. An ISA withdrawal is not income: no income tax, no effect on your personal allowance, nothing on a tax return. Taxable pension income is earned income and stacks on everything else you receive that year. On the calculator's default figures the same £30,000.00 costs £3,486.00 in income tax drawn from a pension and nothing at all drawn from an ISA. No National Insurance is charged on a pension withdrawal.
- Is this a prediction of when I can stop working?
No. The tax half applies published rates that this site checks against gov.uk and dates on the page. Everything else is arithmetic on assumptions you supplied: it computes what would happen if one real growth rate held exactly, every month, for the whole term. Real returns arrive as a sequence and the sequence matters enormously — a poor first decade of drawing sells more of the pot to pay the same income, and this model has no sequence in it at all. Treat the date as what a constant rate would have produced, which is a good way to compare two plans and a poor way to predict a year.