Calculate your Body Mass Index instantly. Metric and imperial units, WHO categories, ideal weight range, and BMI Prime.
Metric (kg/cm) or imperial (lbs/ft-in)
Weight and height — optionally age and sex
BMI, category, ideal weight, and visual gauge
| WHO Category | BMI |
|---|---|
| Severe underweight | < 16 |
| Moderate underweight | 16 – 16.9 |
| Mild underweight | 17 – 18.4 |
| Normal weight | 18.5 – 24.9 |
| Overweight | 25 – 29.9 |
| Obese Class I | 30 – 34.9 |
| Obese Class II | 35 – 39.9 |
| Obese Class III | ≥ 40 |
Want free guides on health, fitness and wellness? Leave your email.
Use our free percentage calculator for changes, discounts, and proportions.
Percentage Calculator →Want to calculate compound interest on your savings?
Compound Interest Calculator →BMI (Body Mass Index) is calculated by dividing your weight in kilograms by the square of your height in meters: BMI = weight / height². For example, a person weighing 70 kg who is 1.75 m tall has a BMI of 70 / (1.75 × 1.75) = 22.9. It is the most widely used indicator to assess the weight-to-height ratio.
The World Health Organization classifies BMI as: Severe underweight (<16), Moderate underweight (16-16.9), Mild underweight (17-18.4), Normal weight (18.5-24.9), Overweight (25-29.9), Obese Class I (30-34.9), Obese Class II (35-39.9), Obese Class III (≥40).
BMI is a useful general indicator for the adult population. It is not accurate for athletes with high muscle mass, elderly people, children, or pregnant women. In these cases, it should be supplemented with other measures such as waist circumference, skinfold measurements, or bioelectrical impedance for a more accurate assessment.
BMI Prime is the ratio of your BMI to 25 (the upper limit of normal weight). A value of 1.0 means you are exactly at the threshold. Below 1.0 you are normal weight, above 1.0 you are overweight. It’s useful for quickly understanding how far you are from the ideal range.
The ideal weight corresponds to the BMI range of 18.5–24.9. For a person who is 170 cm (5’7″) tall, the ideal weight ranges from 53.5 kg (118 lbs) to 72 kg (159 lbs). This calculator automatically shows the ideal weight range for your specific height.
Generate professional texts, emails, bios and slogans in seconds. 10 free credits at sign up — no card needed.