Adult BMI Calculator
Two measurements. Understand your BMI.
For adults aged 20 and older. BMI is a screening measure, not a diagnosis. Do not apply these categories to children, people under 20 or during pregnancy.
Your measurements
Your result
Enter height and weight to calculate BMI.
kg/m²
BMI displays 1 decimal place. Categories use the exact value before rounding.
Value used for comparison
BMI does not distinguish muscle, fat and bone. A health professional needs other health information and measurements to interpret it.
Weight range and health guidance
Reference range at your entered height
This conversion uses BMI 18.5 through 24.9. The lower weight is rounded up and the upper weight down to 0.1 kg to keep displayed values inside that range. The CDC healthy category is 18.5 to below 25.
General reference information and arithmetic, not a diagnosis or an individual nutrition plan. Unusual measurements need professional assessment.
Categories and calculation
BMI = weight in kilograms ÷ height in meters squared. CDC thresholds use the BMI before rounding.
- Below 18.5Underweight
- 18.5 to below 25Healthy weight
- 25 to below 30Overweight
- 30 to below 35Obesity, class 1
- 35 to below 40Obesity, class 2
- 40 or aboveObesity, class 3
Sources checked on 3 October 2026.
What can BMI tell me?
BMI does not distinguish muscle, fat and bone. A health professional needs other health information and measurements to interpret it.
If you are underweight, speak with a doctor or dietitian, especially if you feel weak, tired or lose weight unintentionally. Eat regularly, consider smaller meals, and include nutritious foods and protein. Do not continue losing weight.
If BMI is 25 or higher, discuss muscle, body fat and other health factors with a health professional. Favor balanced meals, suitable activity and sustainable changes. Avoid fasting or rapid weight loss.
General reference information and arithmetic, not a diagnosis or an individual nutrition plan. Unusual measurements need professional assessment.
What happens to my data?
No measurements are sent to a server, saved in history, cookies or analytics. Clear, change language or reload to remove data. An internet connection is needed for the initial page load.
Which tool should you use?
Use Adult BMI for adult screening categories and a weight range at your height.
Use the separate Military BMI tool for Vietnamese recruitment rules, physique scoring and examination-record comparisons.
Open Military BMI