About Tool Guru

Tool Guru is a free collection of online calculators, converters, and generators built for one purpose: giving you answers in seconds, without sign-ups, downloads, or tracking. Every tool on this site runs entirely in your browser using JavaScript — your numbers, text, and data never leave your device.

What we offer

Our library covers three areas of everyday life: Finance (mortgage, loan EMI, compound interest, and salary converters), Health (BMI, body-fat, and calorie-needs calculators), and Everyday utilities (QR codes, passwords, word counts, JSON formatting, timers, color codes, and more). Each tool page also includes plain-English guides so you understand the result, not just the number.

How we build tools

Every calculator is implemented from documented, standard formulas — the same amortization math lenders use, the Mifflin-St Jeor equation dietitians trust, and the U.S. Navy body-composition method. We test each tool against known values before publishing, and we show our work so you can verify results independently.

Our privacy promise

We do not require accounts, we do not sell data, and our tools perform all computation locally. See our Privacy Policy for details.

Who runs Tool Guru?

Tool Guru is an independent project maintained by a small team that believes useful software should be free and private. If a tool helped you, the best thanks is sharing it. Questions or tool requests? Reach us via the Contact page.

Last updated: October 2026.