Health calculators
Free health calculators for adult BMI and maintenance calories. Review formulas, worked examples, applicable ages and limits before interpreting results.
Updated
Understand adult BMI and maintenance energy
The BMI calculator relates adult weight to height and shows the corresponding CDC screening category. The calorie calculator estimates adult resting energy using the Mifflin–St Jeor equation, then applies a selected activity multiplier to describe a maintenance scenario. Both tools explain their formulas and assumptions. Neither measures a person's health directly or replaces a clinical assessment.
Check the intended population first
Adult BMI categories in this tool apply from age 20. Children and teenagers need age- and sex-specific growth references, so their results must not be interpreted using an adult cutoff table. BMI also cannot distinguish fat from muscle or bone, and the tool is not intended for pregnancy assessment. A clinician can interpret measurements alongside medical history and other findings.
The calorie equation supports ages 19–78, matching the original study range. Its male and female coefficients belong to that published model; choosing one does not establish that it suits every individual. Activity factors are explicit assumptions rather than measured energy requirements. The calculator is not for pregnancy, breastfeeding, illness-related nutrition or eating-disorder management, and it does not generate a calorie deficit or weight-loss prescription.
Read numbers without overstating precision
Choose kilograms and centimetres or pounds and total inches before entering values. Five feet nine inches means 69 total inches, not 5.9. Check the unit labels whenever a result looks surprising. Retain the measurement date and assumptions when comparing results over time, and remember that a rounded display can hide values close to a category boundary.
Use these tools to learn the arithmetic and prepare questions for a qualified professional. The body text links to CDC information and the original energy-equation study so you can inspect the basis of the calculation. You can try every feature with invented measurements, and calculations run in your browser without an account. If a result raises a health concern or conflicts with professional guidance, seek appropriate care rather than making a diagnosis or changing treatment from this page. All results are for reference and are not medical advice.