BMI Calculator
Calculate your body mass index and understand what your result means.
Calculate your BMI
Enter your details and choose your preferred unit system.
Your BMI
Healthy BMI range
18.5 – 24.9
Estimated healthy weight range
BMI Range Indicator
What this means
Your measurements
Understanding Body Mass Index (BMI)
Body Mass Index (BMI) is a screening measure that uses your height and weight to estimate whether your body weight falls within a commonly used range. It is useful for identifying potential weight-related health risks, but it should not be used as a diagnosis on its own.
How Is BMI Calculated?
BMI is calculated by dividing body weight by height squared. The formula differs slightly depending on whether metric or imperial measurements are used.
Metric Formula
Imperial Formula
Example: A person weighing 154 lb and measuring69 inches tall:
BMI Categories for Adults
For adults, BMI is commonly classified using the following standard ranges:
| BMI Range | Category |
|---|---|
| Below 18.5 | Underweight |
| 18.5 – 24.9 | Healthy Weight |
| 25.0 – 29.9 | Overweight |
| 30.0 and above | Obesity |
What Does Your BMI Result Mean?
Your BMI result places you into one of the standard weight categories based on your height and weight. A result outside the healthy range does not automatically mean that you have a health problem. Your BMI should be considered together with factors such as body composition, waist measurement, physical activity, diet and overall health.
What BMI Can and Cannot Tell You
BMI is useful because it is simple and quick, but it does not directly measure body fat. It cannot distinguish between muscle, bone and fat, and it does not show where body fat is stored. This means a muscular person may have a higher BMI without having excess body fat.
BMI and Age
Standard adult BMI categories are generally used for adults. For children and teenagers, BMI must be interpreted differently because body composition changes as they grow. BMI-for-age references based on age and sex are used instead of adult BMI cutoffs.
Does BMI Differ for Men and Women?
The standard numerical BMI categories for adults are the same for men and women. However, BMI does not account for differences in body composition, so the same BMI can represent different amounts of body fat in different people.
Why BMI Is Only a Screening Tool
BMI should not be viewed as a complete measurement of health. A more complete assessment may also consider waist circumference, body composition, blood pressure, blood tests, medical history, nutrition, activity level and other individual factors.
FAQs
What is considered a healthy BMI?
For most adults, a BMI from 18.5 to 24.9 falls within the commonly used healthy weight range.
How accurate is BMI?
BMI is useful as a general screening measure, but it is not a direct measurement of body fat or overall health. Muscle mass and body composition can affect the result.
Why can an athlete have a high BMI?
Muscle is denser than fat. A highly muscular person can therefore have a higher BMI even when they have relatively low body fat.
Are BMI ranges different for men and women?
The standard adult BMI cutoffs are the same for men and women, but body composition can differ between individuals.
Can children use adult BMI categories?
No. Children and teenagers require age- and sex-specific BMI-for-age interpretation rather than the standard adult categories.
What should I do if my BMI is outside the healthy range?
Consider your result as a starting point rather than a diagnosis. A healthcare professional or qualified dietitian can help interpret your BMI alongside your individual health and lifestyle factors.
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