BMI calculator: calculate Body Mass Index from height and weight, check adult BMI category, healthy weight range, and metric or imperial results in one place.
Use this BMI calculator to calculate Body Mass Index from height and weight and instantly check the standard adult BMI category, healthy weight range, and matching metric or imperial results.
This is useful for a quick BMI chart check, weight screening, and comparing where a result falls within adult underweight, normal, overweight, or obesity ranges. It can also help connect a BMI result to a practical height-based target range.
The calculator is designed for adults. BMI is a useful screening tool, but it does not directly measure body fat or body composition and can be less informative for children, pregnant people, athletes with high muscle mass, and some older adults.
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Body Mass Index
Normal weight range
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New Body Mass Index
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BMI Prime
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BMI is a screening estimate and may not be appropriate for children and teens under 18, pregnant people, athletes with high muscle mass, older adults, or people with significant edema. For individual assessment, consult a healthcare professional.
Category
| Category | BMI range |
|---|
| Starving | < 16 |
| Underweight | 16 - 18.5 |
| Normal | 18.5 - 25 |
| Overweight | 25 - 30 |
| Obese | 30 - 35 |
| Clinically Obese | 35 - 40 |
| Morbidly Obese | > 40 |
The body mass index (BMI) is calculated with the following formula: BMI = weight(kg) / height(m)2. If pounds and inches are used, a conversion factor of 703 (kg/m2)/(lb/in<2) must be applied.
The new BMI. In 2013 Lloyd N. Trefethen, professor of University of Oxford, proposed a new formula to calculate the BMI of a person: BMI = 1.3 x weight / height2.5. The same conversion factor applies for pounds and inches.
BMI Calculator FAQ
What is BMI?
BMI, or Body Mass Index, is a screening measure that relates body weight to height. It is commonly used to classify adult results into broad ranges such as underweight, normal, overweight, and obesity.
How do you calculate BMI?
The standard formula is BMI = weight (kg) / height (m)^2. This calculator accepts both metric and imperial units and converts them automatically.
What is a normal BMI range?
A commonly used adult normal BMI range is about 18.5 to 25. This calculator also shows the matching healthy weight range for the entered height.
Is BMI always accurate?
No. BMI is a useful screening estimate, but it does not directly measure body fat, muscle mass, age, or body composition. It can be less informative for athletes, older adults, pregnant people, and some children or teens.
Can I use feet, inches, pounds, kilograms, and centimeters?
Yes. You can enter height in cm or ft/in and weight in kg or lb. The calculator keeps the values synchronized both ways.
Is BMI the same for men and women?
The standard adult BMI formula is the same for men and women, but BMI still does not capture differences in body composition, muscle mass, or fat distribution.
Should children and teens use an adult BMI calculator?
Not directly. For children and teens, BMI is usually interpreted using age- and sex-specific percentiles rather than standard adult BMI category cutoffs.
When should I use a BMI calculator?
Use it for quick adult screening, fitness check-ins, medical forms, and comparing your current weight with standard height-based BMI ranges.
