What's my body mass index (BMI)?

Coronavirus and cancer

We know it’s a worrying time for people with cancer, we have information to help. If you have symptoms of cancer contact your doctor.

Read our information about coronavirus and cancer

  • Calculate your Body Mass Index (BMI) below and find out where you are on the scale

What is BMI?

BMI works out if you have a healthy weight for your height.

Is BMI reliable?

Yes, BMI works for most people, and is a reliable indicator of a healthy or unhealthy weight. But, because BMI isn’t a direct measure of body fat, there are a few exceptions to this, such as;

  • Professional athletes and bodybuilders - people with lots of muscle and low body fat could be classified as overweight or obese
  • Children and young people (up to age 18), who have gender and age specific ranges- you can select child on the calculator below

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Waist Circumference

Measuring your waist is another useful way to see if you are a healthy weight. Put the tape measure about an inch above your belly button. If you don’t have a tape measure, try using a piece of string and a ruler.

A healthy waist measurement is:

  • Less than 31.5 inches (80cm) for women
  • Less than 37 inches (94cm) for men

Your ethnic background can influence what a healthy BMI and waist circumference is for you. The cut off point for being considered overweight or obese may be a little lower for people of black, Asian, some Middle Eastern or mixed ethnicity. Talk to a doctor or nurse for more information and support.

Adab, P., Pallan, M. & Whincup, P. H. Is BMI the best measure of obesity? BMJ 360, 15–16 (2018).

NICE. Obesity: identifying, assessing and managing obesity in adults, young people and children. 1–14 (2014).

Freisling, H. et al. Comparison of general obesity and measures of body fat distribution in older adults in relation to cancer risk: Meta-analysis of individual participant data of seven prospective cohorts in Europe. Br. J. Cancer 116, 1486–1497 (2017).

NICE. BMI: preventing ill health and premature ill health and premature death in black, Asian and other minority death in black, Asian and other minority ethnic groups ethnic groups. (2013).

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My BMI is more than 25 – what can I do?


A BMI higher than 25 doesn’t mean you’ll definitely develop cancer. There are lots of steps you can take to stack the odds in your favour.

If you have any questions or concerns about your BMI or waist measurement, visit your GP or nurse who’ll be able to help.