Health
BMI Calculator
Check your Body Mass Index quickly and accurately.
What Is BMI and How Is It Calculated?
Body Mass Index (BMI) is a screening tool that estimates body fat based on your height and weight. It was developed by Belgian mathematician Adolphe Quetelet in the 1800s and is now used worldwide by health professionals as an initial health indicator.
BMI Formula: BMI = weight (kg) ÷ height² (m²). In imperial units: BMI = (weight in lbs × 703) ÷ height² (in²).
BMI Categories (WHO Standard)
- Underweight: BMI < 18.5 — may indicate malnutrition or other health risks
- Normal weight: BMI 18.5–24.9 — associated with lowest health risk
- Overweight: BMI 25–29.9 — increased risk of heart disease, type 2 diabetes
- Obese (Class I): BMI 30–34.9 — high risk; lifestyle changes recommended
- Obese (Class II+): BMI ≥ 35 — very high risk; medical attention advised
BMI Limitations
BMI is a population screening tool, not a direct measure of body fat. Athletes with high muscle mass may have a high BMI without excess fat. BMI also doesn't account for age, sex, ethnicity, or fat distribution. Always consult a healthcare provider for a complete health assessment.
Is a BMI of 25 considered overweight?
Yes, a BMI of 25 falls at the lower boundary of the "overweight" range (25–29.9) per WHO guidelines. However, context matters — a muscular 6-foot athlete with a BMI of 25.5 carries very different health risks than a sedentary person with the same BMI. Use BMI alongside waist circumference and other health markers.
What is a healthy BMI for women vs men?
The standard BMI ranges (18.5–24.9 for normal weight) apply to both men and women. However, women naturally carry a higher percentage of body fat than men at the same BMI. Some researchers suggest a normal BMI of 18.5–23 may be more appropriate for women, while the upper end of 24.9 may be fine for men with more muscle mass.