About Cal

Cal is a small collection of single-purpose calculators. Each page answers one question with a standard, published formula and shows the formula and the assumptions underneath, so you can sanity-check the result instead of trusting a black box.

How the tools work

Every calculator runs entirely in your browser with JavaScript. Nothing you type is uploaded, stored, or attached to a profile; closing the tab discards it. There is no account, no paywall, and no email gate. That also makes the pages fast: the whole site is static HTML, so it loads quickly on a phone with a weak connection.

How the site is funded

Cal is supported by advertising served through Google AdSense. Ads are non-intrusive, labelled, and never placed inside a result. You can accept or reject personalised advertising from the consent banner, and change that choice at any time on the privacy page. Advertising never influences what a calculator computes: results come from the formulas described on the page.

Editorial approach

We prioritise the calculators people actually search for — mortgage payments, loan costs, savings growth, body metrics, percentage and unit conversions. Each page is reviewed for correct units, correct rounding, and clear assumptions. Where a topic is regulated or personal (tax, insurance, medical), the calculator is presented as an educational estimate and the page says so plainly.

Accuracy and limits

We test the arithmetic with fixed inputs and publish the tested inputs in our sitemap-adjacent QA data. Even so, results are estimates: real quotes include fees, taxes, insurance, and local rules we cannot know. Always confirm important decisions with a qualified professional.

Contact

Corrections, suggestions and partnership questions are welcome on the contact page.