About this site

What this is

Twenty-six calculators for the parts of retirement that most retirement calculators skip. The common ones answer a single question — will I have enough? — and there are plenty of good free tools for that; your pension provider almost certainly has one.

These start one step later. They assume you roughly know what you have, and ask the questions that actually decide what happens to it: when the losses land, how much you can flex your spending, what care costs, whether the mortgage should go, whether a bad market would force you to sell at the bottom, and how much you can give the children without it costing you your own security.

The mortgage cluster exists because almost nobody joins mortgage arithmetic to retirement arithmetic, and the honest answer to "should I pay it off?" needs interest rates, inflation, liquidity, sequence risk and estate consequences all at once.

Who makes it

This site is built and maintained by Martin Birrell, independently. There is no company behind it, no investors, no team and no editorial board.

I am not a financial adviser, and nothing here is advice. What the site offers is arithmetic done carefully and explained in full, with every assumption visible and editable. That is a different thing from advice, and for some decisions it is not enough — there is a section below on when it isn't.

Found a number that looks wrong, a calculator that behaves oddly, or an explanation that didn't land? martin.birrell@gmail.com. Corrections are genuinely welcome, particularly on the country presets — see the section on verified figures below.

What is being sold here

Nothing. To be specific, because the absence of each of these is unusual enough to be worth stating:

• No adverts, anywhere, in any form.
• No affiliate links. Nobody pays to be mentioned, and no recommendation anywhere on this site earns anything. Where a calculator names a type of product — annuities, reverse mortgages, REITs — it is describing the thing, not steering you towards it.
• No lead generation. Your details are not collected, sold or passed to an adviser, a broker or anyone else. There is no "speak to a specialist" form because there is no specialist waiting.
• No accounts, no sign-up, no email capture. There is nothing to join.
• No paid tier. All twenty-six calculators are the whole site.

Why free, then? Because the tools already had to exist to answer these questions once, and the marginal cost of leaving them up is close to nothing. That is the entire business model, and if it ever changes this page will say so before anything else does.

What happens to the numbers you type in

Nothing leaves your device. Every calculation runs in your browser, in JavaScript, on your own machine. There is no server doing the sums, so there is nothing to send anywhere and nothing stored at the other end. You can watch this yourself: open your browser's network tab, fill in a calculator, and see that nothing goes out.

The site loads no external scripts, no web fonts, no tracking pixels, no analytics and no third-party anything. Every file it needs is served from the site itself. The only outbound links on the whole site are the primary-source citations in the tax assumptions audit and the official links on the country pages, and those only go anywhere when you click them.

What is stored in your browser

Three things, all of them on your own machine and none of them anywhere else:

• Your country choice, so the picker remembers it next time.
• The figures you type into the calculators — your portfolio, your spending, your guaranteed income, your mortgage — so that moving from one calculator to the next doesn't mean retyping the same six numbers. By default this lasts for the current visit only and disappears when you close the browser.
• Your choice about the above, if you make one.

You are in charge of the second one. The Your figures control in the top bar of every page offers three settings: carry them for this visit only (the default), remember them on this device so they're still here next time, or carry nothing at all and start every calculator blank. The same panel shows how many figures are held and has a Forget everything now button that wipes both stores immediately.

Remember on this device is opt-in and always will be. It is genuinely useful if this is your own computer and you want to come back to a half-finished plan. It is a bad idea on a shared or public machine, and the panel says so at the point of choosing rather than in the small print.

What is never stored, whichever setting you choose

Only fields explicitly marked as shareable are ever read or written — a short list of ordinary financial quantities. Everything else on the site is invisible to that mechanism by construction. That deliberately excludes every question about you rather than your money:

• Whether money has affected your sleep, and how spending makes you feel (calculator 18).
• Your health relative to your age group, and your longevity outlook (calculators 04 and 15).
• How you say you would react to a 30% fall (calculator 04).
• Your assessment of your own chance of needing care (calculator 07).
• Every checklist answer on the estate and complexity scores (calculators 08 and 16).

Those belong to you and stay on the page. A portfolio balance sitting in a browser on a shared computer is one thing; "money has affected my sleep: often" is a different thing, and it is not the site's to keep.

When a calculator has filled a field in for you, it says so underneath it. That is deliberate — a number already in a box gets less scrutiny than an empty one, and on a page about your retirement that matters.

Where the figures come from, and which ones to trust

The calculators contain no tax rules, no government-pension rules and no means-testing logic. That is deliberate. Those rules differ in every country, change often, and a calculator that silently encodes last year's version of them is worse than one that encodes none.

The consequence is a useful one: the calculators cannot be wrong about the law, because they never state any. What they can be wrong about is the starting figures the country picker loads. So those are audited separately, and each carries an honest confidence level:

• verified — checked against a current published source, with the source and check date recorded. Statutory rates mostly sit here.
• indicative — a reasonable planning figure that varies enormously in practice. Care costs are the clearest case: regional variation can exceed a factor of two, so the default is a conversation-starter and nothing more. Replace it.
• n/a — the concept does not exist in that country, and the input is neutralised rather than left to mislead.

The tax assumptions audit lists every jurisdiction-sensitive default, what the law actually says, a link to the primary source, the date it was checked, and — the part most sites omit — which direction each simplification pushes the answer. If you only read one page here before trusting a number, read that one.

The country pages do the same job in plainer language: United States, United Kingdom, Australia, Canada.

How the calculations work

Openly, and in one place. How the maths works sets out the drawdown loop line by line, explains how the simulated market years are generated and why they are drawn the way they are, and lists what the models leave out. It includes arithmetic you can check on paper against what the calculator shows.

Anyone claiming a model of the future should be willing to show you the model. If something there doesn't add up, that is worth an email.

What this site will not do

It will not tell you what to do. That is not modesty or legal throat-clearing — it is a limit of the format. A calculator does not know your health, your marriage, your children's circumstances, your tax position, your employer's scheme, or how you would actually behave in the second year of a bad market. All of those change the answer, and several change it more than the arithmetic does.

Some decisions genuinely need a person:

• Anything turning on tax, which this site does not model anywhere.
• Anything turning on means-tested benefits — the Age Pension in Australia, Pension Credit in the UK, the OAS clawback in Canada, Medicaid in the US. Each can outweigh the decision that costs you eligibility.
• Transferring a defined-benefit or final-salary pension. Almost always a bad idea, occasionally not, never a thing to decide from a website.
• Estate planning of any complexity, and anything involving a trust.
• Any decision that is irreversible and large.

What the calculators are good for is arriving at that conversation knowing which questions matter — which is a much better place to start from, and considerably cheaper.

Accessibility and how it's built

Static HTML, one stylesheet, two small JavaScript files. No framework, no build step, no dependencies, nothing loaded from anyone else's server. Charts are drawn as plain SVG rather than pulled from a charting library, which is why the pages load instantly and why there is nothing to phone home.

Every page works with the keyboard, carries a skip link, labels its inputs properly, and gives its charts text alternatives. Colour contrast is checked against WCAG AA. If something is unusable with a screen reader or at a large text size, that is a bug and worth reporting.

Where to go next

Start here works out which calculators are worth your time. The numbers you'll need covers gathering your figures. How to read the results is the ten minutes most worth spending before you enter anything, and the plain-English list defines every term the site uses.