BMI Calculator

Quickly calculate your Body Mass Index (BMI) to understand whether your weight falls within a healthy range. Useful for everyday health awareness, clinical screening, and guiding lifestyle or medical decisions.

Reviewed: 1 July 2025 • Next Review: 1 June 2026 • Source: WHO • Suggest an edit

Professional & Patient Guide

Clinical Reviewer: S Chishti MRPharmS (UK)

Educational purpose only

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Height

Weight

Enter your details to see
clinical classification.

What is BMI?

Body Mass Index compares weight to height to estimate whether body weight is within a healthy range for most adults.

How BMI is calculated

BMI is calculated using weight divided by height squared. The result gives a single number used to classify weight categories.

Why BMI matters

Higher or lower BMI values are linked to risks such as heart disease, diabetes, nutritional deficiency, and other long-term conditions.

BMI classification ranges

Underweight

Below 18.5

Healthy range

18.5 to 24.9

Overweight

25 to 29.9

Obese

30 and above

Limitations of BMI

Does not distinguish muscle from fat
May misclassify athletes
Does not reflect fat distribution
Varies across ethnic groups
Not suitable in pregnancy

When to take action

BMI outside healthy range
Rapid weight gain or loss
Associated medical conditions
Family history of risk
Concerns about diet or lifestyle

Important reminder

BMI is a screening tool, not a diagnosis. Clinical decisions should consider lifestyle, medical history, and individual risk factors.

If your result is outside the healthy range, consider discussing it with a healthcare professional for personalised advice.