BMI Calculator
Calculate BMI for adults age 20 and older as a screening estimate, not a diagnosis.
BMI Calculator
Calculate adult BMI and view the standard screening category.
Instructions:
- Enter your weight in kg or lbs
- Enter your height in feet & inches or cm
- Formula: BMI = weight (kg) / height (m)²
- Results use standard adult BMI categories for people age 20 or older
Adult screening tool only
This calculator is for adults age 20 or older. Children and teens require age- and sex-specific percentiles. BMI does not directly measure body fat and is not a diagnosis. See the CDC explanation of adult BMI.
Explore More Health Tools
Continue with related pages to compare results and improve decision making.
How This BMI Calculator Works
This adult BMI calculator uses metric or U.S. customary inputs to calculate BMI, show the corresponding adult screening category, and display the weight range corresponding to BMI 18.5–24.9 for the entered height.
Formula and Calculation
The core formula used by this bmi calculator is: BMI = Weight (kg) / Height (m)^2, or BMI = 703 x Weight (lb) / Height (in)^2.
The formula compares weight relative to height. For adults age 20 and older, the result can be grouped into CDC screening categories, but it does not directly measure body fat or diagnose health.
An adult who weighs 70 kg and is 1.70 m tall has a BMI of about 24.2. That falls within the 18.5–24.9 adult screening category, but it does not by itself determine health or body-fat percentage.
How to Use This Calculator
- Enter your weight in kg or lb.
- Enter height in cm/m or feet/inches.
- Run the calculation to view BMI value.
- Read the adult category as a screening result, not a diagnosis or personal weight target.
Why Use This BMI Calculator?
- Calculate adult BMI from either supported unit system.
- See which standard adult screening category contains the result.
- Understand the formula and its limitations.
- Use the result as one data point to discuss with a healthcare professional.
Related Tools and Guides
- Try the Age Calculator for a related calculation.
- Try the Percentage Calculator for a related calculation.
- Read the BMI Calculator Guide for examples and assumptions.
- Browse the Health Calculators page for more tools.