BMI Calculator
Enter your height and weight — your BMI (Body Mass Index), weight category and an ideal-weight estimate appear right away. A simple health reference. Everything stays in your browser.
How to Use the BMI Calculator
Enter your height and weight to instantly see your BMI (Body Mass Index), weight category, and an ideal-weight estimate. Use it as a quick reference for everyday health tracking.
- Enter your Height in centimeters (e.g. 170).
- Enter your Weight in kilograms (e.g. 65).
- The BMI, category, and ideal weight update as you type.
Click an example chip above the inputs (such as "170cm 65kg") to fill in the height and weight and see the BMI and category right away. Trying one first, then editing it to your own figures, is the quickest way to start.
BMI is calculated as weight (kg) divided by height (m) squared. The ideal weight shown is the weight at a BMI of 22 — height (m) squared times 22 — a commonly used reference point.
Worked example: for a height of 170cm and weight of 65kg, 170cm = 1.7m, so BMI = 65 ÷ (1.7 × 1.7) = 22.5 (Normal), and the ideal weight is 1.7 × 1.7 × 22 = 63.6kg.
Everything recalculates automatically as you type — no button to press. Handy when you want to compare several figures quickly.
When This Helps
- Checking your BMI and category before or after a health check-up.
- Using an ideal-weight target as a reference for fitness goals.
- Comparing figures for the whole family in one place.
Weight Categories (WHO)
- BMI under 18.5: Underweight
- 18.5 to under 25: Normal
- 25 to under 30: Overweight
- 30 to under 35: Obese class I
- 35 to under 40: Obese class II
- 40 and above: Obese class III
BMI Is an Adult Screening Index
BMI is weight in kg ÷ height in m²; it does not directly measure body fat. The English classification follows WHO adult guidance—see the official Obesity and overweight fact sheet (last checked July 14, 2026).
Children and adolescents require age- and sex-specific references, not these adult cut-offs. Pregnancy, athletic or unusually muscular builds, older age, and fluid retention can also make BMI differ from body composition or individual health. Clinical assessment can include waist measurement, laboratory results, and medical history.
Do not treat the displayed reference weight as a rapid weight-change target. Discuss concerns with a clinician or registered dietitian. The BMR & Calorie Calculator provides a separate energy estimate with its own limitations.
Ideal and healthy weight by height
"Ideal weight" here is height (m) squared × 22, the BMI associated with the lowest disease risk in Japanese guidance. The healthy range spans BMI 18.5 up to (but not including) 25.
| Height (cm) | Ideal weight (BMI 22) | Healthy range (BMI 18.5–25) |
|---|---|---|
| 140 | 43.1 | 36.3 – 49.0 |
| 145 | 46.3 | 38.9 – 52.6 |
| 150 | 49.5 | 41.6 – 56.3 |
| 155 | 52.9 | 44.4 – 60.1 |
| 160 | 56.3 | 47.4 – 64.0 |
| 165 | 59.9 | 50.4 – 68.1 |
| 170 | 63.6 | 53.5 – 72.2 |
| 175 | 67.4 | 56.7 – 76.6 |
| 180 | 71.3 | 59.9 – 81.0 |
| 185 | 75.3 | 63.3 – 85.6 |
| 190 | 79.4 | 66.8 – 90.3 |
BMI categories (WHO)
| BMI | Category |
|---|---|
| Below 18.5 | Underweight |
| 18.5 to under 25 | Normal |
| 25 to under 30 | Overweight |
| 30 to under 35 | Obese class I |
| 35 to under 40 | Obese class II |
| 40.0 and above | Obese class III |
Displayed values are rounded to one decimal place, but the category is decided from the unrounded value (a BMI of 24.97 shows as 25.0 yet still reads "Normal"). BMI uses only height and weight, so it cannot distinguish muscle, body fat or frame size. This English version follows the WHO categories; the Japanese version uses the Japan Society for the Study of Obesity bands, which split the obese range differently. Results are a general guide, not medical advice.