BMI Calculator
Calculate your BMI from height and weight, with the Japanese classification and healthy weight range.
Inputs are not collected. Usage measurement requires your consent.
Your BMI
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BMI-22 reference weight
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Difference from reference
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* Classification follows the Japan Society for the Study of Obesity criteria (18.5 / 25). Results may differ for muscular or elderly people.
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BMI Calculator
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How to use
- 1
Enter height and weight
Type your height (cm) and weight (kg).
- 2
Check your BMI
Your BMI and classification update in real time.
- 3
See your healthy weight
Compare your weight with the healthy range for your height.
Features
- Japanese obesity criteria (18.5 / 25)
- Real-time BMI and classification
- Healthy weight for your height included
- All in your browser with no data sent
Use cases
Daily health tracking
Track weight changes through BMI over time.
Diet goal setting
See the gap to your healthy weight and set a target.
Health check reference
Understand the BMI field on your medical checkup.
Details
The BMI calculator computes your body mass index from height and weight, then classifies it as underweight, normal or obese based on the Japan Society for the Study of Obesity criteria. It is widely used as a health indicator.
BMI = weight (kg) ÷ height (m) ÷ height (m). By the Japanese criteria, below 18.5 is underweight, 18.5 to under 25 is normal, and 25 or above is obese. Note that muscular people and older adults may have body fat levels that differ from the BMI reading - treat it as a guideline.
Everything runs in your browser and your height and weight are never sent anywhere. The tool also shows your healthy weight for your height (height (m) × height (m) × 22).
FAQ
What is the BMI formula?
Weight (kg) ÷ height (m) ÷ height (m). Example: 170 cm and 65 kg gives 65 ÷ 1.7 ÷ 1.7 = 22.5.
What are the BMI categories?
Under the Japanese criteria: below 18.5 is underweight, 18.5 to under 25 is normal, and 25 or above is obese.
How is the healthy weight calculated?
Height (m) × height (m) × 22. For 170 cm: 1.7 × 1.7 × 22 = 63.6 kg.
Is my input saved?
No. Everything is computed in your browser and your height and weight are never saved or sent.
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Verified: 170 cm and 65 kg (BMI 22.5, Normal weight, reference weight 63.6 kg, +1.4 kg difference), 6-tier boundaries, range errors, and JA/EN display are covered by browser tests
Did you know?
BMI was invented in the 1830s by the Belgian statistician Adolphe Quetelet.