Free Health & Fitness Calculators

Calculate your Body Mass Index (BMI) in metric or imperial units and see which World Health Organization weight category it falls into.

Estimate your Basal Metabolic Rate — the calories your body burns at rest — using the widely used Mifflin-St Jeor equation.

This calculator estimates your body surface area (BSA) — the total external area of the body — in square metres (m²) from your height and weight. It uses the Mosteller formula, a simple square-root method that is widely cited for its accuracy and ease of calculation, and it also references the older Du Bois and Du Bois equation as an alternative. BSA is often regarded as a more representative measure of metabolic mass than body weight alone, because it is less affected by abnormal fat mass. The result here is a general-information estimate only and is not medical advice; if BSA matters for a clinical decision, your height and weight should be confirmed and the figure interpreted by a qualified healthcare professional.

Estimate the calories you burn in a day (your TDEE) by combining your Basal Metabolic Rate with an activity level.

This calculator estimates ideal body weight (IBW) from your height and sex using the Devine formula, a simple equation introduced by Dr B. J. Devine in 1974. It is widely used in clinical settings as a quick reference, originally to help with weight-based medication dosing rather than to set a personal weight goal. The result is a rough population-level estimate: it depends only on height and sex and ignores everything that makes real bodies differ, such as muscle, bone structure, frame size, age and body composition. Treat the number as background information, not a target to aim for, and speak with a clinician or registered dietitian for guidance tailored to you.