Body Math is built and maintained by Johan Gallo, a software developer. I built it after getting tired of jumping between three different calculator sites — one for BMI, one for calories, one for body fat — each with a different interface and no way to see all my numbers together.
Each calculator uses a published, named formula, not a guess: BMI uses the standard CDC formula, calories use the Mifflin-St Jeor equation (the one research has found most accurate for healthy adults), and body fat uses the U.S. Navy circumference method. Every formula is shown in full on its calculator page, with sources cited at the bottom of each article.
It's not medical advice. These are general estimates for healthy adults, not a diagnosis or a treatment plan. Talk to your doctor or a registered dietitian before changing your diet, exercise, or fluid intake, especially if you are pregnant or managing a medical condition.
This site is free and has no paywall, account, or newsletter. It's supported by display ads and Amazon affiliate links (clearly marked) on relevant product recommendations. Neither one changes what the calculators tell you.
Found a formula that looks wrong, or have a calculator you wish existed? See the contact page.