BMI (Body Mass Index) = weight(kg) / height(m)². It categorizes weight status as Underweight (<18.5), Normal (18.5–24.9), Overweight (25–29.9), or Obese (30+).

BMI Prime = your BMI / 25. A value of 1.0 means you are exactly at the top of the Normal range. Below 1.0 is normal or underweight; above 1.0 is overweight or obese.

What is a healthy weight for my height?

Healthy weight range = BMI 18.5–24.9 × height(m)². This calculator shows the exact kg or lb range for your height.

BMI is a screening tool, not a clinical diagnosis. It does not account for muscle mass, bone density, or fat distribution. Athletes may show high BMI despite low body fat.

BMI Calculator

Calculate Body Mass Index, category, healthy weight range, BMI Prime, and how much weight to gain or lose to reach normal.

Weight (kg)

Height (cm)

What is BMI?

BMI (Body Mass Index) = weight (kg) / height (m)². For imperial: 703 × weight (lb) / height (in)². It is a widely used screening tool to classify weight status into four categories:

Underweight — BMI below 18.5
Normal weight — BMI 18.5 to 24.9
Overweight — BMI 25 to 29.9
Obese — BMI 30 and above

BMI Prime is your BMI divided by 25 (the upper bound of Normal). A value of exactly 1.0 means you sit right at the Normal/Overweight boundary. Values below 1.0 are within or below normal range.

Ponderal Index = weight (kg) / height (m)³ — an alternative to BMI that scales better for very tall or short individuals. Normal range is roughly 11–14 kg/m³.

How to Use

Choose Metric (kg + cm) or Imperial (lb + ft/in).
Enter your weight and height.
Click Calculate BMI or press Ctrl+Enter.
The gauge shows where your BMI falls. The result shows your category, BMI Prime, healthy weight range, and how much to gain or lose to reach normal.

Limitations

BMI does not account for muscle mass, bone density, age, sex, or fat distribution. Highly muscular athletes may be classified as overweight despite low body fat. Use BMI alongside waist circumference, body fat percentage, and clinical assessment for a fuller picture. Pair with the Calorie Calculator to estimate daily energy needs for your goal.

Frequently Asked Questions

What is BMI?

BMI = weight(kg) / height(m)². It categorizes weight as Underweight (<18.5), Normal (18.5–24.9), Overweight (25–29.9), or Obese (30+).

What is a healthy BMI?

A BMI between 18.5 and 24.9 is considered normal weight for adults. Below 18.5 is underweight, 25–29.9 is overweight, and 30+ is obese.

What is BMI Prime?

BMI Prime = BMI / 25. A value of 1.0 = exactly the Normal/Overweight boundary. Below 1.0 is normal or underweight; above 1.0 is overweight or obese.

Is BMI accurate?

BMI is a screening tool, not a diagnostic measure. Athletes, elderly, and pregnant individuals may get misleading results.

Is my data sent anywhere?

No. All calculations run in your browser. Your height and weight are never uploaded or stored.