About CalcVerse

What this site is

CalcVerse is 15 browser-based calculators covering maths, percentages, finance, business, salary and tax, health and fitness, dates and time, unit conversion, construction, geometry, statistics, science, engineering, education and everyday arithmetic. Each one has its own page with the formula it applies, a worked example, the assumptions it makes and links to the tools people usually need next.

It exists because most calculator sites answer a question slightly different from the one you asked. “Percentage change” and “percentage difference” return different numbers. A loan payment depends on a compounding convention that is usually invisible. A concrete estimate that omits waste sends you back to the supplier. We try to make the framing explicit on every page.

How the calculations are checked

Every calculator is a plain JavaScript function with a known input and a known expected output recorded alongside it. The test suite runs those cases on every build, and the build fails if any of them drift. The cases are drawn from worked examples in standard references, from published equations, and from hand-computed values.

Specific things we test for:

• Known values. A $200,000 loan at 6.00% over 30 years must produce a payment of $1,199.10. A BMI of 70 kg at 1.75 m must produce 22.9.
• Boundaries. Zero rates, zero terms, single-item data sets, leap days, and the exact edges of classification bands.
• Invalid input. Letters, empty fields, negative values where negatives are meaningless, and division by zero must produce a readable message rather than NaN or Infinity.
• Rounding. Money rounds to two decimal places half-away-from-zero, and amortisation schedules adjust the final payment so the balance lands exactly on zero rather than a fraction of a cent.

The same source file that the tests run is the file the browser downloads, so a formula proved correct in testing is literally the formula that executes on your screen.

Why there is no live data

You will not find a live currency converter, a share-price tool or a weather calculator here. Those need a third-party API, an account and usually a subscription. When any of those lapse — and they do — the tool silently starts returning nothing, or worse, something stale that still looks plausible.

Everything on CalcVerse is deterministic: the same inputs always produce the same output, forever, with no network request. Where a real-world rate is genuinely required, such as an interest rate, a tax rate or an electricity tariff, the calculator asks you for it and shows it in the result, so the number is exactly as current as the figure you entered.

Privacy by architecture

There is no server-side calculation, so there is no server that could see your salary, your weight, your loan balance or your test scores. Those values are typed into a form, processed by JavaScript in your tab, and displayed — they never travel anywhere.

A small number of conveniences use your browser's local storage: your theme preference, the calculators you have starred, and a list of the tools you opened recently. Those stay on your device and can be cleared from the home page at any time. Health, finance and salary calculators deliberately do not remember their inputs at all.

Limits of what a calculator can tell you

A formula is not advice. Financial results here are estimates that exclude fees, insurance, taxes and the pricing decisions of an individual lender. Health calculators implement published population equations that carry meaningful individual variation and cannot diagnose anything. Tax tools apply the rate you supply rather than claiming knowledge of your jurisdiction's current law.

For decisions that matter, use these tools to understand the shape of the problem, then confirm the numbers with a professional who can see your full situation.

How the site is built

Static HTML, CSS and vanilla JavaScript, generated from a calculator registry at build time. No framework, no client-side router, no analytics on your inputs. Each calculator page loads its own category's calculation module and nothing else, which keeps pages small and fast.

Found an error in a formula or a page? Tell us — a reproducible case with the inputs you used is the fastest way to get it fixed.