BMI Calculator

BMI: useful, but limited

BMI (Body Mass Index) is a simple calculation: your weight in kg divided by the square of your height in meters. Created by statistician Adolphe Quetelet in the 19th century, it was designed to describe population trends — not to assess an individual's body composition.

The issue is well-known: BMI does not distinguish fat mass from muscle mass. An athlete at 85 kg for 1.75 m has a BMI of 27.8 — classified as "overweight" — even though their body fat may be 12%.

BMI for strength trainees

If you have lifted seriously for more than 2 years, your BMI is probably overestimated relative to your physiological reality. The more muscle you have built, the less relevant BMI becomes as a health or fitness indicator.

Studies have shown that up to 50% of people classified as "overweight" by BMI among athletes actually have perfectly healthy body composition. The reverse also exists: a "normal" BMI can mask a high body-fat percentage in someone with little muscle.

Which indicators are more relevant for athletes?

To track lifting progress, several indicators are more informative than BMI:

• FFMI (Fat Free Mass Index) : measures muscle mass relative to height, independent of body fat.
• Body fat percentage : obtained via bioimpedance, DEXA scan or skinfold measurements.
• Waist circumference : more predictive of metabolic risk than BMI alone.
• Performance : strength, endurance, mobility — concrete indicators of your progress.

When BMI is still useful

BMI remains genuinely useful for sedentary or lightly muscled individuals, and for large-scale epidemiological studies. It is a simple first filter, not a diagnosis. If your BMI is high and you train regularly, use the FFMI calculator for a more accurate picture of your body composition.