Free health calculators that give you the number in seconds, then explain what it means in plain language. No sign-up, and nothing you type is stored.
How we build these tools
Every calculator uses a published formula that is named on the page, with a link to the research behind it. We explain the limits of each formula instead of hiding them, and we flag results that fall outside the ranges health bodies consider safe. If a better-validated method exists, we use that one and say why.
The tools are written in plain HTML and JavaScript, so they load fast on any phone and run entirely in your browser. We do not collect, save, or send the numbers you enter. New tools are added one at a time, each with its own guide.
These tools give general estimates for healthy adults and are for information only. They are not medical advice and do not replace an assessment by a doctor or registered dietitian, especially if you are pregnant, under 18, or managing a medical condition. See our medical disclaimer.