Free calculator
BMI Calculator
Switch between metric and imperial. The result includes the WHO category and the weight range for BMI 18.5–24.9.
What BMI measures
Body mass index is weight in kilograms divided by height in metres squared (kg/m²). It is a population screening tool, not a diagnosis. The World Health Organization bands are: under 18.5 underweight, 18.5–24.9 normal, 25–29.9 overweight and 30 or above obesity.
BMI does not distinguish muscle from fat, and it does not account for age, sex, bone structure or fat distribution. Athletes can score as overweight, while older adults can carry excess fat at a normal BMI. Waist circumference and body composition add useful context.
Healthy weight range
The range shown is the weight that would place you between BMI 18.5 and 24.9 at your height. It is a broad reference, not a target set by a clinician.
Frequently asked questions
Is BMI accurate for athletes?
No. Muscle is denser than fat, so athletes can have a high BMI with low body fat. Body composition is a better measure for them.
What is a healthy BMI?
The WHO defines 18.5–24.9 as the normal range for adults. It is a screening band, not an individual diagnosis.
Does BMI work for children?
No. Children and teenagers use age- and sex-specific percentile charts, not the adult bands.
Should I use BMI to set a weight goal?
Use it as one signal among several. Waist circumference, medical history and how you feel matter more than a single number.