Free Tool
BMI Calculator
Enter your weight and height in metric or imperial units to get your Body Mass Index, WHO category, and healthy weight range. A general wellness screening estimate — not a diagnosis.
Enter weight + height, then Calculate.
WHO BMI Categories
Underweight
BMI Below 18.5
Normal
BMI 18.5 – 24.9
Overweight
BMI 25.0 – 29.9
Obesity (Class I)
BMI 30.0 – 34.9
Obesity (Class II)
BMI 35.0 – 39.9
Obesity (Class III)
BMI 40.0 and above
BMI (body mass index) is your weight in kilograms divided by the square of your height in metres. The World Health Organization groups adults as underweight below 18.5, normal from 18.5 to 24.9, overweight from 25 to 29.9, and obese at 30 and above — split into Class I (30–34.9), Class II (35–39.9), and Class III (40+).
BMI is a quick population screening tool, not a diagnosis. It does not distinguish muscle from fat or account for sex, age, frame size, or fat distribution, so athletes and very muscular people can read as "overweight" while being metabolically healthy. Treat your number as a general estimate and talk to a clinician about your full health picture.
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Frequently asked questions
How is BMI calculated?
BMI is your weight in kilograms divided by your height in metres squared (kg/m²). For imperial inputs we convert pounds to kilograms and inches to centimetres first, then apply the same formula.
What is a healthy BMI range?
The World Health Organization considers a BMI of 18.5 to 24.9 the 'normal' range for most adults. Below 18.5 is underweight, 25 to 29.9 is overweight, and 30 or above falls into the obesity classes.
Is BMI an accurate measure of health?
BMI is a population-level screening tool, not a diagnosis. It does not distinguish muscle from fat or account for sex, age, or body composition, so a muscular person may read 'overweight' while being metabolically healthy. Use it as a general estimate and discuss any concerns with your clinician.
Does BMI matter for GLP-1 weight management?
BMI is one of the common screening thresholds clinicians reference when discussing weight-management options, including GLP-1 medications. It is a starting point for a conversation, not a prescribing decision — your clinician weighs your full health picture.
What is the healthy weight range for my height?
This calculator shows the weight range corresponding to a BMI of 18.5 to 24.9 for the height you enter, in both kilograms and pounds. Staying within that band is a general wellness target, not a personalized goal.
Is BMI the same for men and women?
The BMI formula and the standard WHO category cut-offs are the same regardless of sex. Body composition differs between individuals, however, so BMI should be interpreted alongside other measures and clinical judgment.
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