About CalcMax
A collection of free online calculators that show their working — and that say, on every page, what they cannot do.
What this site is
CalcMax is a set of online calculators, one page per tool, covering maths, money, health, date and time, unit conversion, physics, statistics and more. There is no account, nothing to install and nothing to sign up for: open a page, type a number, read the result.
Every tool page carries the same five things — the inputs, a reference table showing where your result falls, the formula it uses, a worked example you can check by hand, and a short section on what the tool cannot do. The last one is not boilerplate: it is where the tool states the assumptions it made.
How the numbers are produced
Every calculation runs in your browser. The numbers you type are not sent anywhere and nothing is stored — the result appears as you type, because the arithmetic is happening on your own device.
The formula a page uses is on that page, not in a help article somewhere else. Where a result is rounded, or a unit is converted before it is used, the page says so — you should never have to guess which number was rounded.
Where the formulas and thresholds come from
Formulas and conversion factors are the standard published definitions for the quantity being computed. Where a tool sorts a result into bands — a weight category, a risk score, a tax bracket — the bands and the cut-offs between them are printed in that page's reference table.
The worked examples are arithmetic rather than illustration: they put the numbers into the formula shown on the page and write out each step, so you can reproduce the answer with a pen and paper. If an example does not come out the way the tool says, the tool is wrong.
Who maintains this, and why there are no bylines
CalcMax does not carry reviewer bylines. Every number, formula and threshold is printed on the page it applies to, so you can check any of it yourself instead of being asked to trust a title. The trade-off is that the judgement stays yours — which is why each tool page has a section on its own limits, and why the terms of use carry a disclaimer rather than a promise.
What these results are not
They are estimates. They come from idealised models, so they leave out real-world fees, local rules and individual variation. A calculator cannot tell you what your bank will charge, what a doctor would advise, or what a contract means for you.
Nothing here is medical, legal, tax or investment advice. The terms of use state that in full.