BMI Calculator
Calculate your Body Mass Index and see your weight category. Note: BMI is not accurate for athletes with high muscle mass.
Understanding BMI for Strength Athletes
BMI is calculated by dividing your weight in kilograms by the square of your height in metres. It was originally developed as a population-level statistical tool, not a diagnostic measure for individuals. At a population level, higher BMI correlates with higher rates of cardiovascular disease, type 2 diabetes, and other metabolic conditions - which is why it became a widely used clinical screening tool.
For strength athletes and regular gym-goers, BMI is a poor proxy for health. Muscle is denser than fat, so a highly muscular person will register a high BMI despite having a low body fat percentage. Many elite powerlifters, bodybuilders, and rugby players fall into the "overweight" or "obese" categories by BMI despite being in exceptional physical condition. If you lift regularly, your bodyweight relative to your lifts is a far more meaningful indicator of your fitness level.
Frequently Asked Questions
What is BMI?
Body Mass Index (BMI) is a number calculated from your height and weight. It provides a simple screening tool to categorise weight status: underweight (below 18.5), normal weight (18.5-24.9), overweight (25-29.9), and obese (30 and above).
Is BMI accurate for athletes and lifters?
BMI does not distinguish between muscle and fat, so it frequently misclassifies muscular athletes as overweight or obese. A 90 kg lifter at 180 cm with 10% body fat will show a BMI of 27.8 (overweight) despite being very lean. Use it as a general reference only, not a measure of body composition.
What is a healthy BMI range?
The World Health Organisation defines normal weight as 18.5-24.9. However, optimal BMI varies by age, sex, and ethnicity. Some research suggests slightly higher BMI ranges (22-27) are associated with the lowest mortality risk in older adults.
What is the BMI formula?
BMI = weight (kg) / height (m)^2. In imperial units: BMI = (weight in lb / height in inches^2) x 703. Both calculations give the same result.
What should I use instead of BMI for body composition?
Better alternatives for athletes include body fat percentage (measured via DEXA, hydrostatic weighing, or the Navy tape method), waist-to-height ratio, or simply tracking strength standards relative to bodyweight.