Adult BMI calculator.
A simple measure. A little more context.
Adult BMI is one screening measure, not a diagnosis or a complete assessment of health. Not for people under 20 or during pregnancy. It cannot distinguish muscle from fat and may be misleading for athletes. A qualified healthcare professional can interpret it in context.
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What does BMI measure?
Body mass index, or BMI, expresses body weight relative to height. This calculator uses adult categories for people aged 20 or older. BMI is a screening measure, not a diagnosis, a direct measure of body fat or a complete picture of health.
How to calculate adult BMI.
BMI = weight in kilograms ÷ (height in meters × height in meters)
For 70 kg and 175 cm, first convert height to 1.75 meters: 70 ÷ (1.75 × 1.75) = 22.857…, displayed as 22.9. For imperial measurements, this tool converts pounds to kilograms using 1 lb = 0.45359237 kg, and feet and inches to centimeters using 1 in = 2.54 cm. Enter whole feet plus any remaining inches, from zero to less than 12.
Adult BMI categories.
| Category | BMI range (kg/m²) |
|---|---|
| Underweight | Less than 18.5 |
| Healthy weight | 18.5 to less than 25 |
| Overweight | 25 to less than 30 |
| Obesity | 30 or higher |
These category names follow the CDC’s adult BMI categories. The CDC further divides the obesity category into classes; this calculator shows the four broad categories. A category alone does not establish an individual’s health status.
Why can 25.0 still appear as “healthy weight”?
The displayed BMI is rounded to one decimal, but its category uses the value before display rounding. For example, 24.96 rounds to 25.0 while remaining below the category threshold of 25. A BMI of exactly 25 belongs to the overweight category. The same principle applies at 18.5 and 30. Small differences in measured height and weight can also affect values near these boundaries.
Understand the limits before using the result.
This adult tool is not for people younger than 20, whose BMI interpretation uses age- and sex-specific growth references. It should not be used to assess pregnancy. BMI does not distinguish muscle, fat and bone, so it may not reflect body composition in athletes or people with high muscle mass. It also does not show where body fat is distributed.
A qualified healthcare professional can consider BMI alongside medical history, physical findings and other relevant information. This calculator does not recommend a target weight, calorie intake or weight-loss plan.
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The calculator does not send your height or weight to a server. Calculate & save keeps the latest ten input sets in this browser so you can restore them. Use Clear to remove recent measurements, especially on shared devices.
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