About investmentcalculator.co.uk

Information, not advice

This site publishes information, not advice. It cannot know your circumstances, it does not recommend any product, provider or course of action, and nothing on it is a personal recommendation. For a decision that matters, check the figures against gov.uk or speak to an accountant or a regulated adviser.

Concretely: this site names no provider, ranks no product and recommends no course of action. A calculator that tells you what a rule produces is a factual tool. The moment a site starts telling you which provider to use, it is doing something else, and this one does not.

Why the working is on the page

Most UK calculators return a single number. A single number cannot be checked, and on tax questions it is very often wrong in ways the reader has no way to see — a capital gain taxed entirely at one rate when it straddles two, dividends taxed in isolation from the salary underneath them, a projection whose contribution timing and fee treatment are never stated.

Every page here shows the band-by-band breakdown, the allowances used and left unused, and the assumptions it made. If a figure looks wrong, the working is there to find out where it went wrong. That is the entire proposition, and it is also the only defensible way to publish tax arithmetic to strangers.

• Investment calculatorProject a pot forward from a starting balance, regular contributions, a growth assumption and fees — with the conventions stated. — methodology
• Compound interest calculatorWork out compound interest on a starting amount and regular deposits, with the deposits and the interest separated year by year. — methodology
• Dividend tax calculatorWork out dividend tax on salary plus dividends, band by band, in the statutory stacking order. — methodology
• Capital gains tax calculatorWork out capital gains tax with gains stacked on top of income, showing the annual exempt amount consumed. — methodology
• Capital gains tax on sharesWork out capital gains tax on a share disposal, stacked on your income — and see plainly that the share identification rules are not applied for you. — methodology
• Self-employed tax calculatorWork out income tax and Class 2 and Class 4 National Insurance on self-employed profits, and what is left after both. — methodology
• Corporation tax calculatorWork out corporation tax including marginal relief, and how associated companies move the thresholds. — methodology
• Salary and dividend calculatorCompare salary and dividend splits for a company director, with corporation tax and both National Insurances in the arithmetic. — methodology
• Savings interest calculatorWork out a year of savings interest and the income tax on it, including the starting rate for savings, the personal savings allowance that applies at your income, and what the pound that halves it costs. — methodology
• Pension drawdown calculatorTake tax-free cash and draw an income from a pension pot: the income tax it costs stacked on your other income, and what the pot does over the term. — methodology
• Stocks and shares ISA calculatorProject a stocks and shares ISA forward and price the dividend tax and capital gains tax the wrapper avoids. — methodology
• ISA calculatorWork out how much of the annual ISA allowance is left, split across cash, stocks and shares, innovative finance and Lifetime ISAs. — methodology
• Scotland tax calculatorWork out income tax in Scotland on earnings, savings interest and dividends, alongside the same income taxed in the rest of the UK. — methodology
• Take home pay calculator ScotlandWork out take-home pay in Scotland from a gross salary, after Scottish income tax and UK-wide employee National Insurance. — methodology
• Income tax calculator ScotlandWork out Scottish income tax on earnings across all six bands, with the bands shown in gross income and the rate on the next pound. — methodology
• Salary sacrifice calculatorWork out what sacrificing part of your salary into a pension costs you in take-home pay, as a share of the money — with the employer’s National Insurance saving shown separately. — methodology
• National insurance calculatorWork out National Insurance on pay or profit — employee and employer Class 1 shown separately, with the total cost of the employment, plus Class 2 and Class 4. — methodology
• Annuity calculatorEnter the annuity rate you have been quoted — this calculator does not quote rates — and see the tax-free cash, the income tax on the income stacked on everything else, and the same money as drawdown. — methodology
• Income tax calculatorWork out income tax on earnings, savings interest and dividends band by band, with the bands shown in gross income, the rate on your next pound, and the personal allowance taper priced. — methodology
• Dividend calculatorWork out what a shareholding pays, per payment and per year, and what reinvesting compounds it to — with the income tax on it in the statutory stacking order. — methodology
• Mortgage overpayment calculatorWork out what overpaying a mortgage saves in interest and how much sooner it clears, with the year-by-year schedule and a comparison against investing the same money. — methodology
• Retirement calculatorRun both halves of a retirement plan — the years of paying in and the years of drawing an income — and work backwards from the income you want to what you would have to save. — methodology
• Inheritance tax calculatorWork out inheritance tax on an estate, band by band — with the residence nil-rate band taper priced, gifts charged in date order, and the rate on the next pound shown separately. — methodology
• Pension calculatorWork out what a pension pot grows to — in today’s money as well as in cash — what the tax relief on your contributions is actually worth, whether you and your employer are inside the annual allowance, and the tax on the way out. — methodology
• Junior ISA calculatorProject a Junior ISA to the day it matures, with the balance on the day the child takes control of the account as well — and a year of contributions checked against the child’s own allowance. — methodology
• Bed and ISASell shares in a general account and buy them back inside an ISA: the gain the sale crystallises under HMRC’s share identification rules, the tax on it, the dealing costs and stamp duty, and the same trade with the repurchase outside a wrapper. — methodology
• Investment fee calculatorWork out what platform fees and fund charges cost over the term, as a share of the pot you would otherwise have had — and how little of that ever shows on a statement. — methodology
• Dollar cost averaging calculatorCompare investing a sum all at once with dripping the same money in over time, and see plainly what a fixed-rate model can and cannot tell you about the difference. — methodology
• ETF calculatorProject an ETF holding with a dealing charge on every purchase — the cost that comes out of the money going in and therefore never compounds. — methodology
• Index fund calculatorWork out what an index fund leaves you after the gap between the index and the investor: dividends, the ongoing charge and tracking difference, composed as rates. — methodology
• S&P 500 calculatorProject a plan at a return you supply — this page will not invent one — and see what return you would have needed, what the dollar does to it, and how wide the spread of assumptions is. — methodology
• Net worth calculatorAdd up what you own and subtract what you owe — then price the tax that has not been paid yet: income tax attached to a pension, capital gains tax attached to an unwrapped gain, and inheritance tax on the same estate. — methodology
• Emergency fund calculatorWork out how many months of essential spending your fund covers, what a shortfall would cost to borrow or to raise by selling investments, and the income tax on the interest when it is held outside an ISA. — methodology
• FIRE calculatorWork out the pot your income needs and the year it arrives — with the withdrawal rate as your assumption, and the years between stopping work and reaching pension age priced separately. — methodology
• Coast FIRE calculatorWork out the pot you would need today to stop contributing entirely and still reach your target on compounding alone, and the year your own plan crosses that line. — methodology
• Pension tax relief calculatorWork out the tax relief on a pension contribution and how it reaches you — the part a provider adds at source, the part you have to claim yourself, and the personal allowance a contribution buys back. — methodology
• Pension contribution calculatorWork out what a contribution as a percentage of salary puts into your pension and what it costs you after relief, against the annual allowance, its taper and any unused allowance carried forward. — methodology
• SIPP calculatorWork out what SIPP contributions become once basic-rate relief is added and the pot is projected forward on your own assumption, and the tax-free share and income tax it meets at the other end. — methodology
• Rental yield calculatorWork out gross and net rental yield on one denominator, the return on the cash actually committed, and the income tax on the profit with the finance cost restriction applied. — methodology
• Dividend yield calculatorWork out trailing and forward dividend yield, dividend cover and the payout ratio — and see what the yield after income tax is, and how much of a high yield is a falling price. — methodology
• Bond yield calculatorWork out running yield and yield to maturity from a clean price and accrued interest, then the yield after tax — with the capital gains exemption that applies to gilts. — methodology
• Second job tax calculatorWork out what a second job adds to your tax bill — both jobs taxed once as one income — what a BR code collects instead, and why National Insurance charged per employment makes the same pay cost a different amount. — methodology
• Pension carry forward calculatorWork out unused pension annual allowance carried forward from the three previous years, each at its own allowance, and the order a contribution uses them in. — methodology
• Pension lump sum calculatorWork out the tax on a pension lump sum — the tax-free share and the rest stacked on your other income — and what the same money taken over two tax years would cost instead. — methodology
• Personal savings allowance calculatorWork out which personal savings allowance applies at your income, how much of the starting rate for savings survives, what the unused part of the allowance would actually cost, and the pound of income that halves it. — methodology
• Crypto profit calculatorWork out the profit on a cryptoasset disposal and the capital gains tax on it, stacked on your income — with the pooling rules that decide the cost stated rather than applied. — methodology
• Lifetime ISA calculatorWork out the government bonus on a Lifetime ISA payment and what the withdrawal charge takes back — which is more than the bonus gave, because it is charged on the withdrawal rather than on the bonus — with the first home price cap and the three age limits tested against your own figures. — methodology

What is checked, and what is not

Rates, thresholds and allowances live in one place, are read directly by the calculators, and are checked against gov.uk figure by figure. Every figure in use has been checked at least as recently as 12 August 2026 — that is the oldest check in the log, not the newest, because a set of rules is only verified as of its stalest row and a re-check of one tax year must not re-date a claim covering figures nobody has looked at since. Each methodology page carries that date, the sources and the full log, row by row.

That check covers the rates. The answers are a separate question. Most of the test suite derives its expected values by hand from the same rate files the check covers, so it proves the arithmetic is consistent with the inputs rather than that any answer is right. A smaller set of tests does better: their expected values are taken from HMRC’s own published worked examples — the dividend and savings guidance, the personal allowance taper, HS275 on business asset disposal relief, the corporation tax manual — so those specific scenarios are checked against an authority outside this project.

That distinction is worth the paragraph, because those outside checks found two real errors that every hand-written test had agreed with: marginal relief was computed on the wrong profit measure, and the capital gains exemption was deducted twice across a mixed disposal. Both under-charged tax. Both are fixed. Neither would have been found by a suite written from the same reading of the rules that produced the mistake — which is the whole argument for testing against somebody else’s worked examples, and the reason to be precise about how few of them there are.

No named person has signed that check off yet. It was carried out automatically. It is recorded that way in the source repository and it is said that way here, because the alternative — implying a review that has not happened — is the exact failure this page exists to avoid.

Errors that reach a reader are published on the corrections log, in full and permanently. It is empty today, and it was built before it was needed on purpose.

What this site does with your data

Every calculation runs in your browser. 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.

There is no account, no email capture, no submit button and no result stored anywhere. There is no application server and no database — this site is a folder of files on a content delivery network, so there is nothing here that could receive a figure, act on one, or keep one.

A share link is the exception worth being precise about. Creating one costs nothing: the button rewrites the address bar in your browser and makes no request, so your figures do not leave the tab. Opening one is a page request like any other, and a page request carries its whole address. So when someone follows a link you sent them, the query string — ?salary=50000&dividends=20000 and the rest — reaches the network that serves this site and can appear in its access logs, exactly as it would for any URL on any website. Nothing on this side reads it: the file returned is the same file every visitor gets, and the arithmetic happens after it arrives, in their browser.

Two consequences follow, and neither is hidden. A share link is as private as the place you paste it — a public post makes those numbers public. And search engines are deliberately allowed to fetch parameterised links rather than blocked from them, because that is the only way the page’s canonical can be read and the variants folded back into the plain address; the trade is that a pasted link can be crawled and indexed by a third party. If the figures are sensitive, send a screenshot or the plain address instead.

There are no adverts, no analytics and no cookies at all today, which is why you have not been asked to consent to anything. If that changes, a consent dialog will appear before anything is set, and refusing will be exactly as easy as accepting.

Calculators embedded on other sites under /embed/ load no consent dialog, no advertising and set no cookies, under any configuration. Consent on an embedded widget belongs to the publisher whose page it sits on, not to this site.

How this site is paid for

It is not, yet. There is no advertising and there are no affiliate links today. If either appears, it will be disclosed on the page carrying it, and it will not change what a calculator computes — the arithmetic has no commercial input and no branch that depends on who is paying.

Sources and licence

Rates, thresholds and allowances are taken from material published by HM Revenue & Customs, the Scottish Government and the Scottish Parliament. Every source is linked on the relevant methodology page with the date it was read.

Contains public sector information licensed under the Open Government Licence v3.0.

Who writes it

Sam Ellery
Sam builds and maintains the calculators on this site. Every rate, threshold and allowance behind them is checked against gov.uk before release, and the date of that check is published on each calculator and in a public log. The site exists because most UK calculators return one number and hide the working, which makes them impossible to check and easy to misread. Sam is not a financial adviser or an accountant, and nothing here is advice.

Where a calculator uses statutory figures, each one is checked against gov.uk before release and the date of that check is published on the page. The investment projections have no statutory figures — they are arithmetic on an assumption you supply. The whole of it is covered by an automated test suite, including fixtures built from HMRC’s own published worked examples. No accountant or other professional has reviewed these calculators, and no result they produce has been independently verified.

Sam Ellery is a pen name. The description above is accurate and no qualification is claimed anywhere on this site, because none is held — you will not find a professional body or a register entry listed, and that absence is the honest answer rather than an omission. What can be checked is the arithmetic: every rate carries its gov.uk source and the date it was checked, the method is written out per calculator, and corrections are published.