Krishna Chaitanya — software engineer, 14 years building web applications, based in Glasgow, UK. Currently working at one of the world's largest financial institutions. AWS Cloud Practitioner certified. Built WorthIt Tools out of frustration with ad-heavy, inaccurate calculator sites. GitHub.
Every formula on this site is sourced from peer-reviewed research or official guidance — Mifflin-St Jeor for TDEE, Widmark for BAC, standard amortisation for mortgages, WHO thresholds for BMI. The sources are cited on each tool page.
Questions about a specific formula or want to suggest a correction? Contact page — every message gets read.
WorthIt Tools is a free collection of calculators that give you a straight answer without a pop-up, a paywall, or a forced sign-up. All calculations run in your browser — your numbers never leave your device.
Every time I searched for a simple calculator I landed on sites buried under ads, slow to load, and often wrong. The maths behind a tip calculator or a BMI tool is not complicated — it should not require a bloated web app to deliver. So I built WorthIt Tools: lean, fast, and free.
Living in Glasgow, I also noticed most finance calculators default to US dollars and US tax rules. UK users deserve tools that default to pounds, reference Bank of England rates, and cite HMRC and NHS rather than IRS and CDC.
Each tool uses one of three types of source:
Tools are reviewed when the underlying guidance changes — for example, when HMRC updates tax bands or the NHS revises its BMI classification thresholds.
All calculations run entirely in your browser with JavaScript. Nothing is sent to any server. When you enter your weight into the BMI calculator, that number stays on your device and is gone when you close the tab.
We use Google Analytics for aggregate site traffic only — never individual calculation inputs. Read the full Privacy Policy.
Use the contact page for formula corrections, tool suggestions, or anything else. Email is also on the contact form.