BMI Calculator
Enter your weight and height and your BMI appears instantly. The calculation runs entirely in your browser: no data is sent or stored.
Enter a weight and a height to see your result.
Results are estimates. Solvemis accepts no responsibility for the results obtained or for how they are used. Always double-check the result and talk to a qualified professional before making decisions.
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How it works
How to use it
- Enter your weight in kilograms. You can use either "." or "," as the decimal point.
- Enter your height in centimetres.
- Your BMI and category appear as you type. There is no button to press.
How it is calculated
BMI is weight (kg) divided by the square of height (m). The categories follow the criteria of the Japan Society for the Study of Obesity: underweight below 18.5, normal weight under 25, obesity (class 1) from 25 to under 30 and obesity (class 2 or higher) from 30.
BMI = weight (kg) ÷ height (m)²
Sources
- BMI（e-ヘルスネット） — Ministry of Health, Labour and Welfare
- Obesity and overweight (fact sheet) — World Health Organization
About this calculator
What BMI is
BMI is an index of the relationship between weight and height: weight (kg) divided by height (m) squared. At 70 kg and 1.75 m, it is 70 ÷ (1.75 × 1.75) = 22.9.
The categories
| BMI | Category |
|---|---|
| below 18.5 | Underweight |
| 18.5 to under 25 | Normal weight |
| 25 to under 30 | Obesity (class 1) |
| 30 and above | Obesity (class 2 or higher) |
The WHO’s international criteria class 25 and above as overweight and 30 and above as obesity, but the Japan Society for the Study of Obesity classes 25 and above as obesity. This is because metabolic risks tend to appear at lower BMIs in Asian populations, including Japan.
What BMI tells you and what it doesn’t
BMI is simple and easy to compare, but it doesn’t show what your weight is made of. It doesn’t distinguish muscle from fat or show where the fat is. Visceral fat, around the abdominal organs, is known to affect the metabolism far more than fat under the skin.
So people with a lot of muscle can be classed as obese even with a low body fat percentage. Waist circumference is a useful extra measure you can take at home: 85 cm or more for men and 90 cm or more for women is one of the criteria for metabolic syndrome.
This result is a guide, not a diagnosis. If you are worried about your health, consult a medical professional.
Frequently asked questions
What is a normal BMI?
The Japan Society for the Study of Obesity classes 18.5 to under 25 as normal weight. Below 18.5 is underweight and 25 or more is obesity, which is further divided into classes 1 to 4.
Updated October 1, 2026
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