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BMI Calculator

Calculate your Body Mass Index instantly. Supports metric and imperial units — get your BMI category and ideal weight range.

kilograms (kg)
centimeters (cm)
years (optional)
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Your BMI
1518.525303540+
Underweight
<18.5
Normal
18.5–24.9
Overweight
25–29.9
Obese I
30–34.9
Obese II+
≥35
Min healthy weight
Max healthy weight
To healthy range

BMI Categories Explained

🔵 Underweight (< 18.5)

May indicate nutritional deficiency. Consider a doctor visit if unintentional. Focus on nutrient-dense foods and strength training.

🟢 Normal (18.5–24.9)

Associated with lowest risk of weight-related disease. Maintain through balanced nutrition and regular physical activity.

🟡 Overweight (25–29.9)

Slightly elevated risk for type 2 diabetes and heart disease. Modest weight loss of 5–10% body weight can significantly reduce risk.

🔴 Obese (≥ 30)

Associated with increased risk of chronic conditions. Even small sustainable changes in diet and activity have meaningful health benefits.

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Frequently Asked Questions

A BMI between 18.5 and 24.9 is considered healthy for most adults. BMI below 18.5 is underweight, 25–29.9 is overweight, and 30 or above is classified as obese. Keep in mind that athletes may have a higher BMI due to muscle mass without being overweight.
BMI is a useful screening tool but has limitations. It doesn't distinguish between fat and muscle mass. Athletes can have high BMI while being very healthy, and older adults may have normal BMI but high body fat. It's best used alongside waist circumference and other health measures.
Metric: BMI = weight (kg) ÷ height (m)²
Example: 70 kg ÷ (1.75 × 1.75) = 22.9

Imperial: BMI = 703 × weight (lbs) ÷ height (inches)²
Example: 703 × 154 ÷ (69 × 69) = 22.7
A BMI of 30.0 or higher is classified as obese: Class I (30–34.9), Class II (35–39.9), and Class III severe obesity (40+). If your BMI falls in this range, speaking with a healthcare professional is recommended.
Focus on a calorie deficit through a balanced diet and regular exercise. Aim for 150–300 minutes of moderate activity per week. Building consistent habits — tracking workouts, water intake, sleep, and nutrition — is key for long-term results. Brite app can help you stay on track with all of these habits in one place.
The standard BMI ranges are the same for men and women, but women naturally have more body fat than men at the same BMI. Some researchers suggest this should be accounted for in clinical assessment. Always interpret BMI alongside age, sex, and muscle mass.