BMI Calculator
Calculate your Body Mass Index from height and weight. See your weight category and ideal weight instantly.
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kg
Your BMI
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Underweight
Normal
Overweight
Obese
Ideal weight (BMI 22)
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Difference from ideal
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How to Use the BMI Calculator
BMI (Body Mass Index) is a widely used screening tool to indicate whether a person has a healthy body weight for their height. Enter your height in centimetres and weight in kilograms, then click Calculate BMI.
BMI Formula
BMI = Weight (kg) ÷ Height (m)²
WHO Weight Classification
- Below 18.5 — Underweight
- 18.5 – 24.9 — Normal weight
- 25.0 – 29.9 — Overweight
- 30.0 – 34.9 — Obese (Class I)
- 35.0 – 39.9 — Obese (Class II)
- 40.0 and above — Severely obese (Class III)
Ideal Weight
Ideal weight = Height (m)² × 22. This is the weight at which BMI equals 22, the middle of the normal range.
Limitations of BMI
BMI is a population-level screening tool, not a diagnostic measure. It does not account for muscle mass, bone density, age, sex, or ethnicity. Athletes may have a high BMI despite low body fat. Always consult a healthcare professional for individual health assessment.
Frequently Asked Questions
How is BMI calculated?
BMI = Weight (kg) ÷ Height (m)². For example, someone who is 170 cm (1.70 m) and weighs 65 kg has a BMI of 65 ÷ 1.70² ≈ 22.5.
What is a healthy BMI?
The WHO classifies BMI 18.5–24.9 as normal weight. A BMI below 18.5 is underweight, 25–29.9 is overweight, and 30 or above is obese.
What is ideal weight?
A commonly used formula is BMI 22 × Height (m)². This gives the mid-point of the normal weight range for your height.
Can I use this for children?
This calculator uses adult BMI standards. Children's BMI is assessed differently, using age- and sex-specific percentiles. Consult a paediatrician for children.
Is my data stored?
No. All calculations run in your browser. Nothing is sent to a server.