BMI calculator
Your body mass index, the CDC category it falls in, and the BMI 18.5 to 24.9 range for your height.
How this works, sources, and questions
How it works
BMI is your weight in kilograms divided by your height in meters, squared. Alma converts pounds and feet to metric, rounds BMI to one decimal, and places it in the CDC adult categories: underweight below 18.5, healthy weight 18.5 to less than 25, overweight 25 to less than 30, and obesity 30 or greater, split into class 1 (30 to less than 35), class 2 (35 to less than 40), and class 3 (40 or greater). The weight range shown is BMI 18.5 to 24.9 at your height.
Evidence
The CDC describes BMI as a screening measure, not a diagnosis. It does not tell fat from muscle or bone, so muscular people can score high, and it says nothing about where fat sits or how you eat. The adult categories apply from age 20, regardless of sex or race. Children and teens use BMI-for-age percentiles instead.
Updated
Common questions
How is BMI calculated?
Divide your weight in kilograms by your height in meters, squared. In pounds and inches, multiply weight by 703 and divide by height in inches, squared. Someone who is 5 ft 9 in and 150 lb has a BMI of about 22.2.
What is a healthy BMI for adults?
The CDC puts the healthy weight category at 18.5 to less than 25 for adults 20 and older. For someone 5 ft 9 in tall, the CDC example lists 125 to 168 lb as that range.
Is BMI accurate if I lift weights?
Not very. BMI uses only height and weight, so it can't separate muscle from fat. A body fat estimate or waist measurement adds context that BMI misses.
Does BMI work for kids and teens?
Not with these categories. For ages 2 to 19, the CDC compares BMI with others of the same age and sex using percentiles. Use the CDC child and teen calculator instead.
What should I do with my result?
Treat it as a starting point for a conversation, not a verdict. If you're pregnant, have a medical condition, or have a history of disordered eating, talk with your clinician before changing how you eat.