Adult BMI Calculator
Calculate Body Mass Index for adults age 20 and older using either metric or US units, and see the CDC-defined screening category it falls into.
What this answers:
- What is my BMI from my height and weight, in metric or US units?
- Which CDC-defined adult BMI category does that number fall into?
BMI is a screening measurement, not a diagnosis. It does not distinguish muscle from fat and can be misleading for very muscular or very lean people. This tool does not evaluate anyone under age 20 — pediatric BMI uses age/sex growth-chart percentiles, not these adult cutoffs.
Your BMI
0.0
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This is a screening number, not a diagnosis. Muscle mass, bone density, and body composition can all affect what BMI means for a given individual.
How it's calculated
BMI = weight (kg) / height (m)²
Worked example
An adult weighing 81 kg who is 1.80 m tall: 81 / (1.80 × 1.80) = 25.0, which falls at the start of the "overweight" category.
| BMI | Category |
|---|---|
| Below 18.5 | Underweight |
| 18.5 – 24.9 | Healthy weight range |
| 25.0 – 29.9 | Overweight |
| 30.0 – 34.9 | Obesity, class 1 |
| 35.0 – 39.9 | Obesity, class 2 |
| 40.0 and above | Obesity, class 3 |
Source: Centers for Disease Control and Prevention, Adult BMI FAQ and Adult BMI Calculator (cdc.gov/bmi). Source last checked September 28, 2026. This is a formula/source citation, not a clinical review sign-off — no clinician review is required to publish a plain BMI arithmetic tool, and none is claimed here.
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