Science & Engineering

BMI (Metric)

Calculate Body Mass Index using metric kg and cm inputs.

Body Mass Index uses metric measurements (kilograms and centimeters) to give a standard health screening number. While BMI has limitations, it remains the most widely used population-level screening tool in medicine.

Enter your numbers

Weight (kg)

Height (cm)

Results update as you change the inputs. Calculations run in your browser.

BMI — Normal Weight

24.5

healthy Range: 56.7 – 76.3 kg (healthy weight range)
imperial: 165 lbs, 5'9"

See the formula

Formula and method

BMI = Weight (kg) / Height (m)²

The Quetelet index divides weight in kilograms by height in meters squared. WHO classification: <18.5 Underweight, 18.5-24.9 Normal, 25-29.9 Overweight, ≥30 Obese.

Worked examples

75 kg, 175 cm male

Weight (kg):: 75
Height (cm):: 175

BMI — Normal Weight: 24.5

90 kg, 168 cm individual

Weight (kg):: 90
Height (cm):: 168

BMI — Obese: 31.9

Assumptions and limits

Adult (18+)
General population (not athletes or elderly)

This tool provides an educational estimate. Rules, rates and personal circumstances can change the answer. Review the assumptions before relying on a result. Report a correction.

Common mistakes to avoid

Using BMI for muscular individuals — athletes and bodybuilders often have "overweight" BMI despite low body fat.
Treating BMI as a health diagnosis — it is a screening tool only. Waist circumference and body fat % are better indicators.
Applying adult BMI to children — children use age-specific BMI percentile charts, not adult cutoffs.

Frequently asked questions

Is BMI accurate?

BMI is a population-level screening tool, not an individual health measure. It doesn't distinguish between fat and muscle mass, or how fat is distributed. Waist-to-hip ratio, DEXA scans, and body fat calipers give more accurate body composition data.

What BMI is considered healthy?

18.5-24.9 is the "normal weight" range per WHO. However, research shows slightly higher BMI (22-27) may actually be associated with longer life in some populations. The healthiest BMI depends on age, ethnicity, and individual health factors.