Underweight
< 18.5
Weight status is below the standard adult healthy range.
Adult screening tool
BMI Calculator
Calculate your body mass index using metric or imperial units, see your BMI category instantly, and understand what the result can and cannot tell you.
This calculator is intended for adults. BMI is a useful screening tool, but it does not directly measure body fat or diagnose any disease.
Calculate Your BMI
Enter your height and weight, then choose the unit system you prefer.
Your BMI
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Waiting for input
Healthy weight range
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Estimated from BMI 18.5 to 24.9 for the same height.
Use this result for
Quick screening
A starting point for understanding adult weight status.
Do not use it as
A diagnosis
BMI does not directly measure body fat, health, or fitness.
BMI range visual guide
Your result is plotted on the standard adult BMI scale below.
Underweight
Healthy
Overweight
Obesity
BMI and body fat are not the same
If you want a body-composition view that goes beyond height and weight, compare your BMI with a body fat estimate.
Fast
Get your BMI and estimated healthy weight range in seconds.
Clear
See the standard adult BMI categories used by major health references.
Practical
Use BMI as a starting point before looking deeper at body fat and waist size.
Free
No signup, no download, and no extra tools required.
Adult BMI Categories
Standard adult BMI ranges commonly used by CDC, NHLBI, and other health references.
Healthy weight
18.5 - 24.9
For most adults, this is the normal BMI range.
Overweight
25.0 - 29.9
BMI is above the healthy range and may indicate higher health risk.
Obesity
30.0+
Higher BMI levels are associated with higher risk of weight-related conditions.
| Category | BMI range | What it usually means |
|---|---|---|
| Underweight | < 18.5 | Weight status is below the standard adult healthy range. |
| Healthy weight | 18.5 - 24.9 | For most adults, this is the normal BMI range. |
| Overweight | 25.0 - 29.9 | BMI is above the healthy range and may indicate higher health risk. |
| Obesity | 30.0+ | Higher BMI levels are associated with higher risk of weight-related conditions. |
Example BMI Calculations
A few quick examples help users understand what the number actually looks like in practice.
Example 1
170 cm + 65 kg
BMI 22.5 • Healthy weight
A BMI around 22.5 falls within the standard healthy range for adults.
Example 2
175 cm + 82 kg
BMI 26.8 • Overweight
This BMI is above the healthy range and may be a prompt to check waist size and body fat.
Example 3
5 ft 9 in + 165 lb
BMI 24.4 • Healthy weight
An imperial example that still lands in the standard healthy BMI category.
How BMI Is Calculated
BMI uses only height and weight. That makes it convenient, low-cost, and easy to use at scale, but it also cannot tell the difference between fat mass and muscle mass.
Metric formula
BMI = weight (kg) / height (m)^2
Imperial formula
BMI = weight (lb) / height (in)^2 × 703
Useful for adults: Adult BMI categories are generally used for people aged 20 and older. Children and teens use BMI percentiles instead of the adult ranges above.
Limitations of BMI
A more credible BMI page should explain both the value and the limits of the metric.
BMI does not measure body fat directly
A high BMI may reflect fat, muscle, or both. A normal BMI also does not guarantee low body fat.
Athletic and muscular adults may be overestimated
People with higher muscle mass can have a higher BMI without having excess body fat.
Some groups need more context
Older adults, pregnant people, and those with unusual body composition may need a more tailored interpretation.
Waist size still matters
Abdominal fat distribution can add health risk information that BMI alone cannot capture.
Waist guidance: Health references commonly note higher risk when waist circumference is above 35 inches for women or above 40 inches for men. Waist size is not a diagnosis either, but it helps add context.
BMI Calculator FAQ
BMI stands for body mass index. It is a screening measure based on height and weight that helps estimate whether an adult falls into a standard weight category.
For most adults, a BMI from 18.5 to 24.9 is considered a healthy or normal range.
No. BMI uses only height and weight. Body fat percentage tries to estimate how much of your body is fat tissue. BMI is useful for screening, but body fat gives a more direct view of body composition.
BMI can be less informative for children and teens, pregnant people, older adults, and very muscular adults. In those cases, it is better to combine BMI with body fat, waist circumference, or medical advice.
BMI is only a starting point
If you want a body-composition signal that goes beyond height and weight, compare your BMI with a visual body fat estimate.