Coast FIRE calculator
The pot you would need today to stop contributing entirely and still reach your target by the age you named — and the year your own plan crosses that line.
Calculator
25 years of compounding to do the work. This is the input the coast number is most sensitive to: every extra year is a smaller pot needed today.
In today's money, before tax. The target below is this divided by the withdrawal rate.
Your assumption, not a law — the familiar 4% is an American study's result, not a UK figure. Zero is not a rate this can use, so clearing the box gives 0.1%.
ISAs, general investment accounts, cash. Anything you could draw on 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.
Only used to work out the year you could stop. Coasting is the projection with these switched off.
Everything that reaches the pension: yours, your employer's, and the tax relief added to it.
A real return — what you assume the pot grows by above inflation. Everything here is in today's money, so a nominal rate would make the coast number look smaller than it is. 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. Over thirty years of coasting this is the one cost that never stops, and it compounds against you exactly as growth compounds for you.
The normal minimum pension age. This page does not assert one: it is not in the tax engine behind this site, it has already been legislated to rise, and some older schemes carry a protected age. Check yours and enter it.
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. There is no tax on this page — what the income costs depends on which wrapper it comes out of, and the FIRE calculator prices that. 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 coast number, and the year paying in becomes optional
Your coast number
This page is arithmetic, not a forecast. Every figure below is what would happen if the pot grew at exactly 5% above inflation every single month for 25 years, which nothing does. Real returns arrive in an order and the order changes the answer. There is no statutory figure in this calculation and nothing here has been checked against gov.uk, because a growth assumption is not the sort of thing an authority could confirm.
| The target at 55 (25.0× your annual income) | £750,000.00 |
|---|---|
| Years of compounding left to do the work | 25 |
| Coast number — what you would need today | £235,762.63 |
| What you have now | £90,000.00 |
You are £145,762.63 away from the point where you could stop paying in. With nothing more added, what you have today reaches £286,304.81 by 55, against a target of £750,000.00. The coast number is 31.44% of the target, which is the whole appeal of the idea: the number that lets you stop saving is far smaller than the number that lets you stop working.
What you already have, left completely alone
| What £90,000.00 reaches by 55 with nothing added | £286,304.81 |
|---|---|
| Against the target | £463,695.19 short |
| Years for it to reach the target unaided, from today | 46 — you would be 76 |
You could stop paying in at 39
Keeping the contributions going, the pot crosses the coast line in 9 years, when you are 39 and it is worth £359,374.06. From that point, paying in nothing at all still reaches £753,705.79 by 55.
The coast line is not a fixed number: it falls every year, because there is one year less of compounding left to do the work, while the pot rises. The year above is where the two meet, found by taking the balance the schedule below actually reached at each year-end and asking what it would reach by 55 on its own. It is not a recommendation to stop, and it takes no view on what you would do with the money instead.
| 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 |
| 49 | £767,963 | £20,000 | £38,808 | −£1,993 | £824,778 |
| 50 | £824,778 | £20,000 | £41,645 | −£2,138 | £884,285 |
| 51 | £884,285 | £20,000 | £44,617 | −£2,291 | £946,612 |
| 52 | £946,612 | £20,000 | £47,730 | −£2,451 | £1,011,891 |
| 53 | £1,011,891 | £20,000 | £50,990 | −£2,618 | £1,080,263 |
| 54 | £1,080,263 | £20,000 | £54,405 | −£2,793 | £1,151,874 |
| 55 | £1,151,874 | £20,000 | £57,981 | −£2,977 | £1,226,878 |
Coasting is not retiring, and a pension is behind an age
Retiring at 55 with a pension you cannot touch until 57 leaves 2 years to be paid for out of savings you can actually reach. Coasting from today, the accessible side would be £47,717.56 by then.
| Years to bridge | 2 |
|---|---|
| Accessible savings at 55, if you coast | £47,717.56 |
| Accessible pot that would pay £30,000 a year in full for all 2 | £57,195.94 |
The accessible side runs out in year 2 of 2. Coasting is the easiest thing in the world to achieve inside a pension, because that is where auto-enrolment and salary sacrifice put the money — and a pension coast number says the saving can stop. It does not say the working can, at 55. You would need £9,478.38 more outside a pension by then. Continuing to pay into the accessible side while coasting on the pension is one way people square that, and this calculator does not recommend it or any other — it prices the gap and leaves the decision where it belongs.
Nothing here says stopping contributions is a good idea. Coasting gives up every future year of tax relief, every future employer contribution, and the whole of the margin that would have absorbed a bad decade — and this arithmetic contains no bad decades, because it applies one rate every month. What the page reports is where a rising balance meets a falling requirement on your own assumptions. It is information, not advice, it recommends no rate, no amount, no wrapper and no provider, and no figure on it is a personal recommendation.
What this number is not
The coast number answers “when can I stop saving”. It is not your FIRE number and it is a fraction of it: at 4.00% the target is £750,000.00, and the pot that gets there on its own from 25 years out is £235,762.63. The difference is entirely the compounding you have not done yet, which is why the number rises sharply as the retirement date gets closer and equals the target on the day itself. The FIRE calculator answers the other question — the year the pot reaches the whole target with contributions continuing, and what the income costs in tax depending on which wrapper it comes out of.
Worked example: the number to stop saving, against the number to stop working
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 aiming to retire at 55 on £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, at 5% a year above inflation after a 0.25% charge.
| The target at 55 (25× the income) | £750,000.00 |
|---|---|
| Coast number — what you would need today | £235,762.63 |
| Which is this share of the target | 31.44% |
| What they have now | £90,000.00 |
| What that reaches by 55 with nothing more added | £286,304.81 |
| Years until paying in becomes optional | 9 — at 39 |
Three things in that table are worth pausing on.
- The coast number is a fraction of the target, and that is the whole idea. £235,762.63 against £750,000.00 — 31.44% of it. The difference is entirely the 25 years of compounding that have not happened yet, which is why the number climbs steeply as the date approaches and equals the target on the day.
- Coasting is easiest to reach in the wrapper you cannot spend from. Of the £90,000.00 here, £75,000.00 is inside a pension — which is the ordinary shape of a UK plan, because auto-enrolment and salary sacrifice put money where the tax relief is. Retiring at 55 with an access age of 57 leaves 2 years to fund from the accessible side, and the panel above says whether it covers them.
- Nothing here says stopping is a good idea. Coasting gives up every future year of tax relief and employer contribution, and the whole of the margin that would absorb a bad decade. This arithmetic has no bad decades in it — it applies one rate every month for 25 years — so the figure it produces is the best case of a model that cannot produce a worst one.
Methodology and sources
What coast FIRE actually asks
Full financial independence asks when can I stop working, and the answer is a date. Coast FIRE asks something else: what pot, left completely alone, arrives on time? The answer is a balance. Once you have it, compounding does the remaining work and every further contribution is optional — you are not retired, you have stopped saving.
That is why this is a separate page from the FIRE calculator rather than a section of it. The two hold different things fixed and solve for different unknowns, and the coast number is a small fraction of the FIRE number. A single page would have had to bury one of them, and it would have buried this one, because the bigger figure is the louder headline and the wrong answer to this question.
The target, and whose result the 4% is
The pot the plan aims at 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 is not British. The 4% figure comes from the Trinity study — withdrawal rates tested against United States stock and bond returns over 30-year retirements. It is a measurement of one market over one horizon. This site holds no market data of any kind, so it cannot confirm that rate, improve on it, or hand you a better one, and it will not present it as a property of money. It is a box you can change, and the target moves the moment you do.
How the coast number is worked out
By re-running the projection, not by discounting the target. The calculator searches for the least starting balance whose schedule — no contributions, your growth rate, your charge, the years between now and your retirement age — finishes at or above the target, and it searches in whole pence, so the answer is the smallest penny that gets there and one penny less provably does not.
The tempting shortcut is target ÷ (1 + rate) ^ years. It is wrong for the same reason this site refuses closed forms everywhere else: a platform charge is not linear in the balance and rounding to the penny every month is not linear in anything, so the discounted figure agrees with the schedule most of the time and misses it by a few pounds exactly where a reader checks. A number produced by the same loop that produces the table cannot disagree with the table.
The year at which paying in becomes optional is found by scanning rather than solving, because both sides of it move: the coast line falls every year as there is less compounding left to do, while the balance rises. Each year-end balance from the contributing schedule is projected forward on its own, and the first one that clears the target is the answer.
The period step, and today’s money
The projection runs in months. 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 no headline can disagree with the schedule it was read off. Contributions at the end of the month is the more conservative of the two conventions and is fixed here rather than offered as a field; the investment calculator is where it is a choice.
Everything is in today’s money, so the growth rate is a real return. 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 into one comparison. On this page that error runs in the flattering direction — it would make the coast number look smaller than it is — which is exactly why the field asks for a return after inflation and says so.
This page carries no verification stamp, and it should not
There is not one statutory figure on it. No tax rate, no threshold, no allowance, no tax year. The growth rate, the charge, the contributions, the ages and the withdrawal rate are all yours, and there is nothing in them an authority could confirm. So this page makes no gov.uk verification claim and will not borrow one from the tax pages on this site; saying nothing would read as an oversight, so it says why instead.
A fixed-rate projection is not a forecast. Nothing grows at the same rate every month. Real returns arrive in an order and the order changes the outcome — and it matters more here than almost anywhere, because coasting means deliberately removing the contributions that would otherwise have absorbed a bad decade. The claim this page makes is arithmetic: given these inputs and the conventions above, the schedule is what they compound to, and the year-by-year table is there so you can check it.
The one thing on the page with a tax dimension is deliberately not priced here. What the eventual income costs depends on which wrapper it comes out of — an ISA withdrawal is not income, taxable pension drawdown is — and the FIRE calculator prices both. Keeping it there is what lets this page be honestly free of statutory figures rather than nearly free of them.
The pension access age is a field, not a fact
A defined contribution pension cannot be touched until the normal minimum pension age. That age is not in the tax engine behind this site, it has already been legislated to rise, and some older schemes carry a protected age of their own — so this page asks for it rather than asserting one, and a calculator that typed a year in would be publishing an unverified figure wearing the appearance of a statutory one. It is also a live risk to a plan: an age that moves moves the years you have to bridge, and no arithmetic here can price that.
What this calculator does not model
- Any sequence of returns. One rate, every month, for the whole term. This is the largest gap between the arithmetic and a real plan, and coasting is the decision it bears on most, because it is the decision to stop adding new money.
- Tax, of any kind — on the way in, on the way out, or on an accessible pot held outside an ISA. Contributions are treated as arriving whole, which flatters a pension (the relief is already in the figure you enter) and flatters a general investment account (its dividends and gains are taxable).
- The state pension — no age, no amount, no forecast. It changes a real plan considerably and it is not here.
- The ISA subscription limit, which caps how fast the accessible side can be built and is therefore a real constraint on bridging a gap. It is a published figure, and it is on the two pages that carry published figures: the ISA calculator and the FIRE calculator.
- Anything about you. No life expectancy, no health, no partner, no property, no redundancy, no children. This is information, not advice: it does not recommend a rate, an amount, a wrapper, a product or a provider, and it does not recommend stopping your contributions.
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.
Coast FIRE questions
- What is coast FIRE?
It is the point at which you have enough invested that, without paying in another pound, compounding alone gets you to your retirement target by the age you want to stop. You are not retired and you are not financially independent — you still need an income to live on — but the saving is done. On the calculator's default figures, someone aged 30 aiming at £750,000.00 by 55 needs £235,762.63 today, which is a far smaller number than the target itself.
- How is the coast FIRE number calculated?
It is the smallest starting pot whose projection — no contributions, your growth assumption, your charge, the years between now and your retirement age — finishes at or above your target. This calculator finds it by re-running the projection rather than by discounting the target backwards, because a platform charge is not proportional to the balance and rounding to the penny each month is not proportional to anything, so a discounted figure disagrees with the schedule shown underneath it. The search runs in whole pence, so the answer is the least penny that gets there.
- Is coast FIRE the same as FIRE?
No, and the difference is the point. FIRE is the pot that lets you stop working: your annual income divided by a withdrawal rate. Coast FIRE is the pot that lets you stop saving: what you would need today for compounding alone to reach that target by your retirement age. The second is a fraction of the first and arrives decades earlier. The FIRE calculator on this site answers the other question, including what the income costs in tax depending on which wrapper it comes out of.
- Can I coast FIRE with just my pension?
You can reach a coast number inside a pension easily — it is where auto-enrolment and salary sacrifice put most people's money, because it is where the tax relief is. What that gets you is permission to stop saving, not permission to stop working. A pension cannot be touched until the normal minimum pension age, so if you want to retire before that age you also need enough outside a pension to live on until it unlocks. The calculator asks for the two pots separately for exactly this reason and prices the gap.
- Should I stop contributing once I hit my coast number?
This page will not tell you that. Stopping gives up every future year of tax relief, every future employer contribution — which is usually the largest single reason not to — and the whole of the margin that would absorb a decade of poor returns. This arithmetic contains no poor decades: it applies one rate every month for the entire term, so the number it produces is the best case of a model that cannot produce a worst one. What the calculator does is show where a rising balance meets a falling requirement on your own assumptions. It is information, not advice.
- What growth rate should I use for coast FIRE?
This site cannot tell you, and any calculator that names one is quoting somebody else. There is no market data behind this page — no return series, no index, nothing — so the rate is your assumption and the answer is only as good as it. What matters more than the number you pick is that it is a real return, after inflation: spending is stated in today’s money here and so is the target, so a nominal rate would make the coast number look considerably smaller than it is. Try more than one rate and look at the spread rather than at any single answer.
- Why does my coast number keep going up?
Because it is a function of how much compounding is left, and every year there is one year less. The number rises as your retirement date gets closer, gently at first and then steeply, and on the day itself it equals the whole target. That is also why moving the retirement age is the single input the coast number is most sensitive to: an extra year at the end does more for it than an extra year of contributions in the middle.
- Is this a prediction?
No. Nothing on this page uses a published figure of any kind, so there is nothing here that has been or could be checked against gov.uk, and the page carries no verification stamp for that reason. What it computes is what would happen if one growth rate held exactly, every month, for the whole term — and real returns arrive as a sequence, which this model has no notion of. Treat it as arithmetic on an assumption you supplied: useful for comparing plans, poor for predicting a balance.