BMI calculator
Body Mass Index (BMI) Calculator
Enter your details to find out which category you fall into and what a healthy weight is for your height.
Your ITM
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Underweight
< 18.5
Normal
18.5 - 24.9
Overweight
25 - 29.9
Obesity
≥ 30
Healthy range
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18.5–25 ITM
Healthy weight
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for your height
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What is body mass index (BMI)?
BMI is an indicator that measures weight in relation to height and is used to assess body mass. It is calculated using the formula: weight (kg) / height² (m). It is widely used as a general indicator of whether a person is at a healthy weight for their height – although it is not a perfect tool, it serves as a useful starting point for assessing whether further tests or lifestyle changes are necessary.
ITM restrictions
BMI is a useful guide, but it does not take body composition – the distribution of muscle mass, bone and fat – into account. Here’s why:
- In the case of athletes and people with high muscle mass, BMI may indicate that they are overweight, even though they are in excellent physical condition
- Older people usually have more body fat than younger people with the same BMI
- Women generally have a higher percentage of body fat than men for the same BMI
The ITM is a good starting point, but it is no substitute for a one-to-one consultation with a dietitian.
BMI categories for adults (WHO)
The following classification applies to men and women aged 20 and over:
| Category | ITM (kg/m²) |
|---|---|
| Severely underweight | < 16 |
| Moderately underweight | 16–17 |
| Slightly underweight | 17–18 May |
| Normal weight | 18.5 – 25 |
| Overweight | 25–30 |
| Class I obesity | 30–35 |
| Class II obesity | 35–40 |
| Class III obesity | > 40 |
Risks associated with being overweight
Being overweight increases the risk of a number of serious health problems, according to the Centres for Disease Control and Prevention (CDC):
- High blood pressure
- Elevated LDL cholesterol (“bad”) and reduced HDL cholesterol (“good”)
- Type 2 Diabetes
- Coronary heart disease and stroke
- Gallbladder disorders
- Osteoarthritis
- Sleep apnoea and breathing problems
- Increased risk of certain types of cancer
- A reduced quality of life and psychological problems such as depression and anxiety
Risks associated with being underweight
Being underweight also carries serious health risks:
- Malnutrition and vitamin deficiency
- Osteoporosis and an increased risk of fractures
- Weakened immune system
- Growth and development problems in children and teenagers
- Hormonal imbalances and reproductive problems in women
- Increased risk of complications during surgical procedures