The majority of adults in the UK are overweight or obese according to national health surveys, yet research suggests we are a country in denial about our weight.

Use this calculator to find out your own body mass index (BMI) and see how you compare with the rest of the nation. You will also get tips from health experts and useful links to information on how to improve your health.

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How the calculator works

Comparative data for this calculator comes from the most recent national health surveys from the four constituent nations of the UK (see data sources below).

Your BMI

We calculate BMI using the standard formula of a person's mass in kg divided by the square of their height in metres (kg/m2) and display it to one decimal place.

Where a user's data is entered in imperial units, we first convert to metric and then carry out the BMI calculation.

The BMI result is assigned to a standard category:

  • Less than 18.5 – underweight
  • 18.5 to 24.9 – healthy weight
  • 25 to 29.9 – overweight
  • 30 to 39.9 – obese
  • 40 and over – very obese (also known as morbidly obese)

Experts say that for people of an Asian descent, 18.5 to 23 is a healthy BMI. We highlight this fact in a later section.

BMI does not take into account body composition so some people who are lean and carry a lot of muscle may have a BMI which does not necessarily reflect their health status.

However, Prof Naveed Sattar from the Institute of Cardiovascular and Medical Sciences at the University of Glasgow says this is likely to apply to far less than 1% of individuals.

The waist circumference measurement is an additional check which can be used in conjunction with BMI.

Your age group

This section compares the user's BMI result with the mean average BMI for their sex and age group in their nation (as defined by the postcode entered in the form).

The Northern Ireland health survey does not publish average BMI data so this comparison is excluded when an NI postcode is entered.

Results for all nations are shown in 10-year age bands apart from the lower end (16-24) and upper end (85+ in England, 75+ in all other nations)

The silhouette body shapes represent the range of BMI categories. We worked with original images developed by Prof Martin Tovee of the University of Lincoln.

England data is broken down into five categories from "underweight" to "very obese".

Scotland and Wales have four categories, with those who are "very obese" included in the "obese" category.

Northern Ireland has three categories: "healthy or underweight", "overweight" and "obese or very obese".

In all cases, the breakdown reflects the data available.

Percentages may not sum to 100 due to rounding.

Your part of the UK

This part of the results shows the percentage of adults who are overweight or obese in the area of the UK that matches the user's postcode.

The figures are divided into male or female, to match the user's details.

The Welsh figure may be an underestimate, as the survey asks for self-reported measurements.

What does this mean for you?

Information in this section was written in conjunction with Prof Naveed Sattar from the Institute of Cardiovascular and Medical Sciences at the University of Glasgow, and experts at Public Health England.

Your waist size

Information in this section was also written in conjunction with the medical experts. The details about how waist size influences risk of developing certain diseases comes from NHS England.

Data sources

We used data from the most recent national health surveys for England, Wales, Scotland and Northern Ireland.

All the surveys apart from Wales measure their respondents' height and weight in order to calculate BMI.

The Welsh survey asks for self-reported measurements which may lead to an underestimate of BMI, according to the survey's statisticians.

England

Health Survey for England data was taken from the spreadsheet Health Survey for England, 2016: Adult overweight and obesity – tables on this page.

Wales

National Survey for Wales data for overweight / obesity was taken from the spreadsheet Additional tables – Population health: health-related lifestyle (adults), 2016/17 on this page.

We also received on request age-group breakdowns of the other BMI categories.

Scotland

Scottish Health Survey data was taken from the spreadsheet Part 13 BMI on this page.

Northern Ireland

Health Survey NI data was taken from the spreadsheet Health Survey NI Trend Tables on this page.

Calculator produced by Christine Jeavans, Scott Jarvis, Sumi Senthinathan, Anya Saunders, Joe Reed, Rachel Baldwin and Charlie Campbell.

With thanks to Prof Naveed Sattar, Institute of Cardiovascular and Medical Sciences, University of Glasgow and Prof Martin Tovee, School of Psychology, University of Lincoln, and Public Health England