Is BMI accurate for everyone?

No. BMI does not distinguish muscle from fat, so muscular athletes often register as overweight despite low body fat. It also may misclassify older adults, and some ethnic groups face health risks at lower BMI thresholds. It is a useful population screening tool, not a diagnosis.

What is a healthy BMI range?

For most adults, the WHO defines 18.5 to 24.9 as the healthy range. The calculator shows the weight range that corresponds to that BMI band for your height.

What should I do if my BMI is high?

Look at complementary measures first: waist circumference, waist-to-height ratio, and body composition. If several markers are elevated, small sustained changes — a modest calorie deficit, more daily movement, resistance training — beat aggressive short-term diets. Discuss significant changes with a healthcare professional.

Health & fitness tool

BMI Calculator

Q: How is BMI calculated?

BMI = weight (kg) ÷ height (m)². In imperial units: 703 × weight (lbs) ÷ height (inches)². The result places adults into WHO categories: under 18.5 underweight, 18.5-24.9 healthy, 25-29.9 overweight, and 30+ obesity.

Body Mass Index is a quick screening number based on your height and weight. Enter your details to see your BMI, its WHO category, and the healthy weight range for your height — results update as you type.

Your BMI 0.0

WHO category —

Healthy weight range for your height —

Where you stand

BMI Categories

The World Health Organization defines four adult bands. The marker shows where your current BMI falls.

Underweight <18.5 Healthy 18.5–24.9 Overweight 25–29.9 Obesity ≥30

FAQ

BMI Questions

How is BMI calculated?

Metric: weight (kg) ÷ height (m)². Imperial: 703 × weight (lbs) ÷ height (inches)². Example: 70 kg at 1.75 m → 70 ÷ (1.75 × 1.75) = 22.9, which falls in the healthy band.

What are the WHO categories?

Under 18.5 is underweight; 18.5–24.9 is healthy weight; 25–29.9 is overweight; 30 and above is classified as obesity (with sub-classes 30–34.9, 35–39.9, and 40+). The same cutoffs apply to adult men and women.

Does BMI measure body fat?

Not directly. BMI correlates with body fat at the population level but says nothing about composition. A 100 kg athlete with 12% body fat and a sedentary 100 kg person share the same BMI. Waist circumference, waist-to-height ratio, and DEXA or skinfold measurements add context.

Why does ethnicity matter?

Research shows some populations — including people of South Asian and East Asian descent — experience elevated cardiometabolic risk at lower BMI values, and some health systems use lower overweight cutoffs (e.g., 23) for those groups. Talk to your doctor about thresholds relevant to you.

Is BMI valid for children?

No. Children and teens are assessed with age- and sex-specific BMI percentiles rather than adult bands. This calculator is intended for adults aged 20 and over.

What is a healthy weight range?

For your height, it is the span of weights whose BMI falls between 18.5 and 24.9. The calculator computes it automatically and displays it in your chosen units.

Disclaimer

Health Estimate Disclaimer

BMI is a screening estimate, not a diagnosis of body fatness or health. This tool does not provide medical advice. Consult a qualified healthcare professional for a personal assessment.