Welcome to our Body Mass Index (BMI) calculator.
BMI is a general indicator of whether or not someone is a healthy weight relative to their height.
Our calculator shows you your BMI, your BMI health category, where you fall on the BMI scale, and your healthy weight range.
Whilst BMI can be a very useful metric, it is important to understand its limitations, so scroll below the calculator to get a detailed breakdown of what exactly BMI is, and what exactly it does and doesn’t tell you.
|Healthy weight||18.5 – 24.9|
|Overweight||25 – 29.9|
|Obesity Class 1||30 – 34.9|
|Obesity Class 2||35 – 39.9|
|Obesity Class 3||40 and Above|
*Please note that the BMI categories for Black, Asian, and some other minority ethnic groups are slightly different from those above. Keep scrolling to view these differences.
Want to visualize BMI further? - Jump to BMI healthy weight charts.
Who Is This Calculator For?
This calculator is for adults, men or women, who want to calculate their BMI. It is not suitable for calculating the BMI of children, as this requires a different equation.
BMI is a useful measurement that can be used to assess whether or not an individual is a healthy weight.
However, if you are worried about your health, please speak to a healthcare professional.
In particular, if you have an eating disorder, the BMI results do not apply, and you should speak to a doctor.
Related: Weight Loss Guides
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What Exactly Is My BMI?: The Body Mass Index Explained
Body mass index or BMI is a measure of your weight compared to your height. It is measured in kg/m2.
BMI is useful, as it can indicate whether or not someone is overweight or obese, conditions which are linked to a higher risk of illnesses such as type-2 diabetes, heart disease, and cancer.
In this way, for most adults, BMI gives a decent estimate as to whether or not they are a healthy weight.
Limitations Of BMI
BMI does not account for muscle mass. Therefore, due to the fact that muscle weighs more than fat, muscular adults can occasionally be incorrectly classified as overweight according to their BMI.
These overestimations tend to occur in the 25-35 BMI range.
On the other end of the spectrum, most of the world's top long-distance runners would be considered underweight according to their BMI, despite them being incredibly healthy in reality.
If you are unsure about your BMI result, you can also measure your waist-to-height ratio, which is an additional indication of healthy body fat. Or, check out our body fat calculator.
Ethnic Differences In BMI and Disease Risk
It is important to note that the healthy BMI range for Black, Asian, and some other minority ethnic groups is lower.
This is likely due to differences in muscle mass and ways in which fat is stored in the body.
In particular, some research shows that BMI is a weak indicator of weight-related health for those of South Asian ethnicity. Body fat calculation methods such as hip-to-waist ratio or our Body Fat Calculator have been shown to be better indicators of weight-related health among South Asians.
There are disputes as to what exactly the BMI category cutoff points should be for different ethnic groups. Currently, in Japan and China, overweight is defined as a BMI greater than 24, and obesity is defined as greater than 28. In India, overweight is defined as a BMI of greater than 23 or higher, and obesity is defined as 27 or higher.
Amongst white populations, diabetes prevention is needed once individuals are classed as being obese (BMI greater than 30). However, recent studies show that diabetes prevention measures are required at lower BMIs for other ethnicities. The research suggests that diabetes prevention is needed at or above a BMI of:
- 24 in South Asian populations
- 27 in Arab and Chinese populations
- 26 in Black Caribbean populations
- 27 in Black Other populations
- 29 in Black African populations
- just below 30 in Black British populations
BMI Healthy Weight Charts
These BMI healthy weight charts can further help you visualize the Body Mass Index categories.
Click here to download the BMI Chart (Imperial/US) as a PDF.
Click here to download the BMI Chart (Imperial/US) as a PNG image.
Click here to download the BMI Chart (Metric) as a PDF.
Click here to download the BMI Chart (Metric) as a PNG image.
How Is BMI Calculated?
BMI is calculated as your weight in kilograms divided by the square of your height, as outlined in the formula below.