Adult BMI Calculator
Calculate body mass index from height and weight, switch between US and metric units, and view the adult BMI category ranges used by CDC.
Try a sample adult input
Body mass index
25.1
BMI category
Overweight
Healthy weight range estimate
125 lb to 169 lb
Underweight
Below 18.5
Healthy weight
18.5 to 24.9
Overweight
25.0 to 29.9
Obesity
30.0 or greater
BMI is weight in kilograms divided by height in meters squared.
Adult BMI categories are screening ranges and do not diagnose health or body composition.
Use adult measurements
This page is for adults 20 and older; children and teens use BMI percentiles.
Keep medical context separate
Pregnancy, muscle mass, ethnicity, age, and health history can change interpretation.
BMI = weight (kg) / height (m)^2
US inputs are converted to kilograms and meters before applying the same formula.
BMI does not directly measure body fat or diagnose health. It can miss important context such as muscle mass, pregnancy, age, ethnicity, and medical history.
Calculations are handled in the browser for this tool based on the current public implementation. Avoid entering sensitive health details unless you have reviewed the implementation.
Example
A 70 kg adult at 1.75 m has BMI = 70 / 1.75^2, which is about 22.9.
Assumption
Adult category labels follow common CDC BMI ranges for adults 20 and older.
Limitation
BMI does not account for muscle mass, pregnancy, body composition, ethnicity, age-related changes, or medical history.
Adult screening
Calculate BMI and compare it with common adult category ranges.
Unit switching
Use US or metric units without manually converting height and weight.
Healthy range estimate
Estimate the weight range associated with common adult BMI categories.
Health notes
Use the result as a discussion point, not as a diagnosis.
Using BMI as a diagnosis
BMI is a screening estimate, not a medical diagnosis. It cannot evaluate body composition or individual health risk by itself.
Using adult categories for children
This calculator is for adults 20 and older. Children and teens use age- and sex-specific BMI percentiles.
Ignoring body composition context
Muscle mass, pregnancy, ethnicity, age, and medical history can all change how BMI should be interpreted.
What is a healthy BMI for adults?
CDC adult categories list healthy weight as BMI 18.5 to 24.9.
Is BMI different for children?
Yes. Children and teens use age- and sex-specific BMI percentiles, not the adult categories shown here.
Why can BMI be misleading?
BMI uses only height and weight, so it does not account for muscle mass, fat distribution, pregnancy, or individual medical context.
Can I use metric units?
Yes. Switch to metric to enter height in centimeters and weight in kilograms.
Suggested workflow
Health estimate path
Use BMI, calories, and sleep timing as simple planning estimates with clear limitations.