How to use the BMI Calculator
- Choose metric or imperial measurements.
- Enter weight and height in the units shown beside each field.
- Review the BMI, category, and reference weight range while considering the limitations below.
How the calculation works
BMI = weight (kg) ÷ height² (m²)For imperial inputs, BMI = 703 × weight in pounds ÷ height in inches squared. The result is compared with common adult screening thresholds: under 18.5, 18.5–24.9, 25–29.9, and 30 or above.
Example calculation
A weight of 70 kg and height of 1.75 m gives BMI = 70 ÷ 1.75² = 22.86, which falls within the standard adult reference range of 18.5 to 24.9.
How to interpret the result
BMI is a population-level screening measure, not a direct measurement of body fat or health. Muscle mass, age, pregnancy, ethnicity, and medical history may affect how a result should be interpreted.
Notes and assumptions
- Category labels use common adult thresholds and are not intended for children or pregnancy.
- The calculation does not distinguish muscle, bone, fat, or fluid mass.
- This educational result is not a diagnosis or medical advice. Consult a qualified healthcare professional for personal guidance.
BMI Calculator questions
What is a healthy BMI?
A BMI from 18.5 to 24.9 is a common adult reference range, but individual health cannot be assessed from BMI alone.
Is BMI accurate for athletes?
It may classify a muscular person higher because it does not distinguish muscle from fat.
Can children use the adult BMI categories?
No. Child and teen BMI is interpreted using age- and sex-specific growth charts by qualified professionals.