How we calculate

Methods

Each tool implements a documented formula or conversion — for example amortising loan payments, Mifflin–St Jeor for calorie estimates, WHO adult BMI bands, or published unit definitions (an inch is 25.4 mm exactly). Finance and tax tools use simplified bands or rates that we update when rules change; they still omit many personal circumstances.

Where a tool has an in-depth explanation or a longer guide, that copy is meant to match the on-screen maths so you can audit the result.

Privacy

Almost every calculation runs in your browser. The numbers and text you type are not uploaded to produce the result. We keep light analytics (which tools are opened, search queries) so we can improve the site. See the Privacy Policy for advertising cookies and admin sign-in.

Sources and limits

Tax bands, ISA and IRA limits, stamp duty, and holiday calendars come from public government or widely used reference sources (HMRC, IRS, GOV.UK, ECB reference rates via Frankfurter, Nager.Date for many public holidays). They can change faster than we update a page. If a tool mentions a tax year, treat it as current at the time of writing and confirm on the official site before you file or exchange contracts.

Health tools (BMI, calories, body fat, sleep, water, macros) are screening or planning estimates. They are not diagnosis, treatment, or a substitute for a clinician.

Who writes this

Josh builds and maintains Utiio independently. Guides and tool explanations are written to be useful on first read, not to replace regulated advice. If something looks wrong, tell us.