About

What CalcDelta is

CalcDelta currently has 734 calculators across finance, health, dates and time, unit conversion, mathematics, construction and everyday topics. The site interface is available in 30 languages. The full 734-calculator catalogue is translated in English, German, Spanish, French, Japanese and Portuguese; 68 selected calculators are also available in 24 additional languages. Pages are designed for browsers on phones, tablets and computers. No sign-up or app is required.

How we fight thin pages

Google indexes thousands of CalcDelta URLs across languages. Growth alone is not the goal. Flagship tools get deep dives with compute()-verified examples, refused inputs, and named formula sources (for example the CFPB note on fixed monthly mortgage payments). We are not adding new languages or thin calculator shells for their own sake; new work goes into making existing high-traffic pages harder to copy and easier to trust.

Why we built it this way

Most calculator sites are built to maximise page views rather than to answer a question. They bury the input fields under interstitials, split a single calculation across several screens, and leave you guessing whether the answer is trustworthy. We wanted the opposite: a page that loads instantly, shows the formula it uses, names the authority that formula comes from, and then gets out of the way. Because the site is plain static HTML, pages stay small and open quickly even on a slow connection.

How each calculator is built and checked

Each calculator is defined by a machine-readable specification covering its inputs, units, defaults, formula and explanation. The build uses that specification to generate the page, controls, results and worked example. The example is computed from the same calculation logic as the interactive page at build time, which helps keep them aligned.

Where the formulas come from

Calculators are grouped into domains such as finance, health, mathematics and dates. Domain links offer background reading, but they do not by themselves verify every formula. On reviewed calculator pages we link to sources for the particular formula or reference values and state important assumptions.

Worked examples you can verify by hand

Each result page opens with a worked example: a set of realistic input values, the result they produce, and a short note on how to read that result. The aim is to let you size up the tool before you rely on it. If you enter the same values and get a different answer, that is worth telling us about.

Accuracy, rounding and the limits of a calculator

We check the arithmetic, but a calculator cannot know your circumstances. Results are rounded for display and may differ slightly from a value computed at full precision. Reference values — interest rates, tax thresholds, nutritional data, dosage ranges, building requirements — change over time and vary by country, region and lender. Treat every result as an estimate, and confirm anything consequential against the primary source or a qualified professional. Our calculators are general information tools; they are not financial, medical, legal or engineering advice.

Editorial standards, corrections and update dates

We try to describe what each calculator does in plain language, without overstating what it can tell you. Where a formula depends on a convention that varies — how a week is counted, say, or which rounding rule applies — the page states which convention is used instead of hiding the assumption. If you find an error, a broken formula or a misleading explanation, email us with the page address and the values you entered. We correct confirmed errors and, where a change is material, note it on the page.

Who runs CalcDelta

CalcDelta is built and maintained by an independent developer who writes the calculator specifications, checks the formulas and answers the email. There is no editorial board and no corporate sponsor, and we would rather say that plainly than imply a level of institutional review the site does not have. If you need to know who is responsible for a page, this is it.

Funding and privacy

There is no paid tier. Calculations run in your browser. Non-default inputs may appear in the page URL so you can reopen or share a calculation. If that URL is opened, its values are sent as part of the request to our hosting provider. Avoid sharing URLs containing sensitive values. We use GoatCounter for site visit statistics. Advertising is served by Adsterra, a third-party ad network, and appears on site pages. Adsterra may receive your IP address, the page URL and device details, and may use cookies to select and measure ads. Its privacy policy explains what it collects and how to exercise your rights.