About MoneyMetric

Financial calculators that show their working — built because most of the alternatives either oversimplify the maths or bury the answer under advertising.

Most financial decisions come down to arithmetic that nobody teaches you. What does an extra percentage point on a mortgage rate actually cost? How much does an extra $150 a month take off a credit card balance? Is the difference between a 6% and a 7% return worth worrying about over thirty years?

These are answerable questions. The formulas are well established and have been for centuries. The problem is that the tools for applying them are usually either too simplistic to be useful — a mortgage calculator that ignores property tax understates the real payment by a quarter — or built to capture a lead rather than answer the question.

MoneyMetric exists to do one thing properly: give a correct, clearly explained answer, quickly, with the assumptions visible. 9 calculators, no account, no upsell, no lead capture.

Correct mathematics, always

Every calculator uses the standard formula for its problem — amortization, compound interest, annuity present and future value — and each one is covered by an automated test suite that runs on every change. Where a result depends on an assumption, we solve it exactly rather than approximating.

Assumptions stated, not hidden

A retirement projection that ignores inflation is not simpler, it is wrong. Every calculator lists what it assumes and what it leaves out, in plain language, directly under the result. If a number looks lower than you expected, you can see why.

Your numbers stay yours

Calculations run entirely in your browser. Your salary, balances and savings goals are never sent to a server, because there is no server-side calculation. There is no account to create and nothing to sign up for.

Fast on any connection

Pages are server-rendered and statically generated, charts are code-split and loaded only when needed, and the fonts are self-hosted. The site should feel instant on a phone on a slow connection, not just on a desktop.

How the site is funded

MoneyMetric is free to use and supported by advertising. We place ads in a small number of fixed positions — below the introduction, between the calculator and the explanatory content, and before the FAQ — and never inside the calculator itself, beside its buttons, or anywhere they could be clicked by accident. If an ad ever makes a calculator harder to use, that is a bug, and we would like to hear about it.

What we are not

We are not a bank, lender, broker, investment adviser or tax preparer. Nothing on this site is personalized financial advice, and no result should be treated as a prediction. The calculators tell you what the arithmetic says given your inputs; whether those inputs are the right ones for your situation is a question for a qualified professional. Our disclaimer sets this out in full.

Something wrong, or missing?

If you spot an error in a calculation, an out-of-date tax figure, or a calculator we ought to build, please tell us. Corrections are the most useful mail we get.

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