BMI Calculator
Calculate your Body Mass Index and find your classification.
About this tool
The BMI Calculator computes the Body Mass Index from weight in kilograms and height in centimeters, displaying the numerical result and the corresponding classification according to World Health Organization criteria: underweight, normal weight, overweight, and the three degrees of obesity.
To use it, enter the weight (in kg) and height (in cm) in the respective fields. The BMI is calculated and displayed automatically, along with a visual bar showing where the result falls on the scale.
Common uses include personal health tracking, referencing a number for medical or gym intake forms, and as a starting point in conversations with healthcare professionals. Nutrition, physical education, and nursing students also use the tool for quick calculations in academic work.
An important note: BMI is a population screening indicator that does not account for body composition, fat distribution, muscle mass, sex, age, or ethnicity. The result from this tool is informational and does not replace evaluation by a healthcare professional. For any concerns about health or weight, consult a doctor or registered dietitian.
The tool runs entirely in the browser — no weight or height data is sent to servers, no account is required, and use is completely free.
Frequently asked questions
Is the BMI calculator free?
Yes, free with no usage limits.
Is the weight and height data I enter sent to any server?
No. All calculations are performed locally in your browser. No data is transmitted.
Does it work on mobile?
Yes. The interface is responsive and works in any modern browser on a phone.
Is the BMI result a medical diagnosis?
No. BMI is a screening indicator and does not replace evaluation by a healthcare professional. For health questions, consult a doctor or dietitian.
What classifications does the tool use?
WHO classifications: Underweight (< 18.5), Normal weight (18.5–24.9), Overweight (25–29.9), Obesity class I (30–34.9), class II (35–39.9), and class III (≥ 40).