Body Mass Index (BMI) is a screening number calculated from height and weight: weight in kilograms divided by height in meters squared.

What is a healthy BMI range for adults?

According to the World Health Organization, a BMI between 18.5 and 24.9 is generally considered a healthy weight range for most adults.

Is BMI accurate for athletes?

BMI does not distinguish fat from muscle. Athletes and very muscular people may have a higher BMI without excess body fat. Use BMI as a starting point, not a diagnosis.

How does Useit calculate BMI?

Useit converts your inputs to metric if needed, then computes BMI = weight (kg) ÷ height (m)² and maps the result to WHO adult categories.

Useit for calculations

BMI Calculator

Get your Body Mass Index in seconds. Switch metric or imperial, see your WHO category, and understand what the number means — privately in your browser.

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Enter height and weight to see your Body Mass Index instantly.

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Healthy BMI range 18.5 – 24.9

Category guide WHO adult standard

How BMI is calculated

BMI = weight (kg) ÷ [height (m)]². Imperial inputs are converted automatically. Categories follow common adult WHO cutoffs: underweight (<18.5), normal (18.5–24.9), overweight (25–29.9), and obesity (30+).

BMI calculator FAQ

What is a good BMI?

For most adults, 18.5–24.9 is the healthy range. Individual needs vary — pregnancy, age, and muscle mass all matter.

Can I use feet, inches, and pounds?

Yes. Choose Imperial in the calculator to enter ft/in and lb.

Does Useit store my height or weight?

No. Everything runs locally in your browser. Refreshing the page clears the form.

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Try the daily calorie calculator to estimate maintenance, mild loss, and mild gain calories.