BMI Calculator: Body Mass Index with Interpretation
Quick answer: Enter your height and weight to calculate your Body Mass Index (BMI) and see your WHO classification. BMI is a screening tool — interpret it alongside other health markers.
BMI Calculator
How BMI is interpreted
- Below 18.5 — underweight
- 18.5 to 24.9 — normal weight
- 25.0 to 29.9 — overweight
- 30.0 to 34.9 — obesity class I
- 35.0 to 39.9 — obesity class II
- 40.0 and above — obesity class III (severe obesity)
Source: World Health Organization (WHO) BMI classification.
Limitations of BMI
BMI does not distinguish between muscle and fat. Athletes with high muscle mass may have a high BMI without excess body fat. BMI also does not account for fat distribution — central (abdominal) adiposity carries higher cardiovascular risk than peripheral fat at the same BMI. For clinical assessment, BMI should be combined with waist circumference, body composition, and metabolic markers.
Frequently asked questions
What is a healthy BMI range for adults?
WHO defines BMI 18.5–24.9 as normal weight for adults. This range is associated with the lowest mortality risk in population studies. Individual targets vary based on age, ethnicity, body composition, and other health markers.
Is BMI accurate for athletes?
Not always. BMI cannot distinguish muscle from fat. Athletes with high muscle mass often register as overweight or obese on BMI but have low body-fat percentage and excellent metabolic health. Body composition analysis (DEXA, BIA) gives better assessment for muscular individuals.
Should I use BMI for children?
BMI in children is interpreted using age- and sex-specific percentile charts (CDC or WHO growth charts), not the adult cutoffs. Use a paediatric BMI calculator for children under 18.
Does BMI apply equally to all ethnic groups?
Research suggests Asian populations may have higher cardiometabolic risk at lower BMI thresholds. The WHO has proposed lower cutoffs (overweight ≥23, obese ≥27.5) for screening Asian populations, though general adult BMI categories remain the global standard.
Last reviewed: by iMedic Medical Editorial Team. Our editorial process.