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Miraç Özdemir
Body Measurements & Weight

Body Mass Index (BMI) Calculator

Calculate your body mass index (BMI) from weight and height, see your WHO class, the healthy weight range for your height and how much weight separates you from it.

Version 3

Things to keep in mind:

  • BMI applies to adults aged 18 and over only; children and adolescents are assessed with the WHO BMI-for-age percentiles.
  • The BMI classification is not used during pregnancy or breastfeeding.
  • BMI does not distinguish fat from muscle: it may overestimate fatness in athletes and muscular people and underestimate it in older adults or people who have lost muscle. Check waist circumference and waist-to-hip ratio for fat distribution.
  • WHO has suggested lower action points for Asian populations; this calculator uses the general international WHO cut-offs.
  • The result is an estimate, not a medical diagnosis or treatment advice; consult your physician or dietitian for decisions about your health.

Calculator

Body measurements

Enter your body weight in kilograms (e.g. 72.5).

Enter your height in centimetres (e.g. 175 or 172.5).

After the first calculation, the result updates automatically when you change a value.

Result

Enter the values and press Calculate to see the result here.

About this tool

Body mass index (BMI) is weight divided by the square of height. It is a screening measure used to classify weight status in adults. This calculator applies the World Health Organization (WHO) adult classification.

Formula

  • BMI = weight (kg) ÷ height (m)²
  • Healthy weight range = 18.5 × height² to 24.9 × height²

WHO classes and class code

  • 1 – Underweight: BMI < 18.5
  • 2 – Normal: 18.5–24.9
  • 3 – Overweight (pre-obese): 25.0–29.9
  • 4 – Obese class I: 30.0–34.9
  • 5 – Obese class II: 35.0–39.9
  • 6 – Obese class III: ≥ 40.0

If you are outside the healthy range, the calculator also shows how many kilograms you would need to lose or gain to reach its nearest limit.

Example: for 95 kg and 180 cm, height² = 3.24 m² and BMI = 95 ÷ 3.24 = 29.3 (code 3, overweight). The healthy range for this height is 59.9–80.7 kg, so reaching its upper limit means losing about 14.3 kg.

Example 2: for 70 kg and 175 cm BMI is 22.9 (code 2, normal); the healthy range for this height is 56.7–76.3 kg, so both weight differences show 0. For 50 kg and 175 cm BMI is 16.3 (code 1, underweight); the lower limit of the range is about 6.7 kg away.

How to read the result: BMI is a general screening indicator, not a diagnosis: the class code tells you where the value falls in the WHO classification. The healthy weight range shows the weights that correspond to a BMI of 18.5–24.9 for the same height. "Weight to lose" or "weight to gain" is only the mathematical gap to the nearest limit of that range; it is not a personal target weight or programme recommendation. Because BMI does not distinguish muscle, bone and fat distribution, interpret the result together with other measures such as waist circumference and with a health professional.

How to use

  1. Enter your weight in kilograms.
  2. Enter your height in centimetres.
  3. Press Calculate.

Notes

BMI is rounded to 1 decimal place (HALF_UP) and the WHO class is assigned from the rounded value (e.g. 24.95 → 25.0 → code 3). The weight range and differences are rounded to 1 decimal place. A difference is only shown when the rounded BMI is outside 18.5–24.9; inside the range both differences are 0.

Sources

References

  1. [1]
    Obesity and overweight (WHO fact sheet)WHO

Frequently asked questions

5 questions

  1. Weight in kilograms is divided by the square of height in metres. For 70 kg and 1.75 m: 70 ÷ (1.75 × 1.75) = 22.9.

Next step

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