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Everyday numbers — age, health and conversions. Free, private and instant — every tool runs in your browser.
Length, weight and temperature — inches to mm, pounds to kg, Fahrenheit to Celsius and more.
Exact age in years, months and days — plus total days lived and your next birthday.
Body Mass Index from height and weight — metric or imperial — with the healthy range for your height.
Every tool in this category is free to use without an account, works on phones and computers, and processes your input locally in your browser — nothing is uploaded or stored. Results are calculated with published formulas and exact conversion factors, and each tool page shows the formula and a worked example so you can verify the maths yourself.