BMI Calculator
Assess body mass category according to World Health Organization weight-to-height standards.
Parameters & Inputs
Summary & Breakdown
WHO Adult BMI Categories
About the BMI Calculator
Body Mass Index (BMI) is an international screening metric established by the World Health Organization (WHO) to classify adult nutritional and weight status. By normalizing weight relative to height, it provides a fast epidemiological proxy for adiposity.
While BMI is a valuable population screening tool, it does not distinguish between lean skeletal muscle tissue and adipose fat mass. Bodybuilders and strength athletes often register as "overweight" despite low body fat, while sedentary individuals may carry excess visceral fat at normal BMI.
Use this calculator to determine your category, estimate healthy weight target boundaries, and establish baseline biometric trends.
How the Calculations Work
Calculates BMI by dividing body mass in kilograms by height in meters squared, or using the 703 conversion factor for pounds and inches.
Metric: BMI = weight_kg / (height_m)^2 | Imperial: BMI = 703 * weight_lbs / (height_in)^2
Variables & Definitions
- weight_kg: Total body weight in kilograms
- height_m: Stature height in meters
- 703: Mathematical conversion constant for imperial units
For an adult weighing 70 kg at a height of 175 cm (1.75 m): BMI = 70 / (1.75)^2 = 70 / 3.0625 = 22.86 (rounds to 22.9), placing the individual in the Normal Weight category.
Key Terms Explained
Body Mass Index
A weight-for-height ratio used widely in medicine to categorize underweight, healthy weight, overweight, and obesity.
Visceral Fat
Deep abdominal adipose tissue surrounding internal organs, closely correlated with metabolic and cardiovascular risk.
Lean Body Mass
Total body weight minus all adipose fat tissue, including muscle, bone, water, and vital organs.
Adiposity
The relative state or degree of carrying body fat.
Practical Tips & Pitfalls to Avoid
Pair with waist measurements
A waist circumference over 35 inches (women) or 40 inches (men) signals health risks regardless of BMI.
Track body composition
If you lift weights, use caliper or circumference measurements alongside BMI to track fat loss versus muscle gain.
Weigh in consistently
Weigh yourself first thing in the morning after using the bathroom to avoid daily water weight fluctuations.
Set sustainable goals
Targeting 1 to 2 pounds (0.5 to 1 kg) of weight loss per week preserves lean muscle mass and metabolic rate.
Frequently Asked Questions
A weight of 70 kg at a height of 175 cm yields a BMI of exactly 22.9, which falls directly within the healthy normal weight range (18.5 €“ 24.9).
No. Heavy muscle mass increases weight without increasing health risk, frequently producing falsely elevated BMI readings for athletic individuals.
According to WHO standards, a BMI between 18.5 and 24.9 indicates normal weight for adult men and women.
Standard adult BMI ranges are identical for adult men and women, though women naturally carry a higher percentage of healthy essential body fat.
Yes. Cardiovascular fitness, blood pressure, insulin sensitivity, and lipid panels are more comprehensive health indicators than BMI alone.