Navigation

BMI calculator

BMI, or body mass index, is one way of measuring whether you’re a healthy weight for your height.

The result gives an indication of whether you’re a healthy weight for how tall you are, and if not, how over or underweight you are. BMI isn’t always the best measure to use because there are other things that you need to consider when it comes to weight (see our limitations information further down the page). But it can be a useful guide.

Simply enter your details into our calculator to find out what your BMI is and whether you’re a healthy weight.

Height and Weight

What is your height?

“”

“”

“”

What is your weight?

“”

“”

“”

Please enter your height and weight to get your result

<p class="f21">Your BMI suggests you’re underweight. Your ideal weight is between $range</p>

<p class="f21"> Your BMI suggests you’re a healthy weight. Your ideal weight is between $range</p>

<p class="f21">Your BMI suggests you’re overweight. Your ideal weight is between $range</p>

<p class="f21">Your BMI suggests you’re obese. Your ideal weight is between $range</p>

“”

What your BMI result means

 You’re in the underweight range, with a BMI score under 18.5.

If you’re underweight, you might not be getting the energy or nutrients that your body needs. This can make you tired, and exercising might feel hard. It can also put you at risk of health conditions such as osteoporosis (brittle bones) and fertility problems.

Your weight is determined by lots of factors. If you regularly consume less calories than your body needs, you can become underweight. Some health conditions such as thyroid problems can also lead to weight loss. And mental health issues such as depression can cause a loss of appetite. Eating disorders are another cause of low body weight.

How to increase your weight safely

Aim for three balanced meals a day. These should include carbohydrates, protein, and healthy fats. If you want to gain weight, you can also include some nutrient-dense snacks. Good examples include:

  • a handful of unsalted nuts
  • a pot of Greek yogurt
  • peanut butter on wholegrain toast

Talk to a GP for more advice. You may also be referred to a dietitian to help you create a personalised meal plan.

Healthy eating

A balanced, nutritious diet is essential for healthy growth and to enable your body to function properly.

Read more

Healthy weight for adults

Although being overweight can cause health problems, it’s important to remember that being underweight can too.

View more

Portion size guide

Eating too much or too little of any of the major food groups can be bad for your health.

Show more

What your BMI result means

A BMI score of between 18.5 and 24.9 is classed as a ‘healthy weight’.

Being a healthy weight can reduce your risk of developing health problems in the future, such as heart disease and type 2 diabetes. Eating well will help you to maintain a healthy BMI. A balanced diet contains protein, fibre, and healthy fats to keep you fuller for longer. Reducing ultra processed foods  can help too. You can increase the amount of energy you use by staying physically active. This means doing 150 minutes of moderate exercise a week, including two sessions of strength training.

Benefits of exercise

Doing regular exercise is great for keeping your weight under control, and can boost your mental as well as physical health.

Read more

What is BMI?

How is BMI calculated, and what are the limitations of using it?

View more

What is a healthy weight for adults?

Keeping eye on your weight and making sure it stays within a healthy range, will reduce your risk of numerous health problems.

View more

What your BMI result means

A BMI score of between 25 and 29.9 is classed as ‘overweight’.

This category of BMI is associated with a higher risk of health conditions, such as high blood pressure, heart disease and certain types of cancer.

Healthy weight loss

If you want to lose weight, a good approach is to reduce your calorie intake by around 600 calories per day. This can be achieved by reducing high calorie foods such as sugary drinks, and ultra processed foods  such as biscuits and crisps. Consuming plenty of fibre and protein will keep you fuller for longer and help to prevent overeating. Managing stress and sleeping well can also make it easier to eat well. Increasing your physical activity has many benefits and can help to you to use more energy each day.

What is a healthy weight for adults?

Although being overweight can cause health problems, it’s important to remember that being underweight can too.

Learn more

Portion size guide

Eating too much or too little of any of the major food groups can be bad for your health.

Learn more

How to maintain weight loss in a sustainable way

How to avoid fad diets and maintain your weight loss in a sustainable way.

Find out more

Bupa Weight Management Plan

The Bupa weight management plan is designed for people with a BMI over 30 (or over 27 if you have a weight related condition). The plan is designed to empower you to achieve and maintain a healthy weight in a sustainable way.

To book or to make an enquiry, call us on 03452660566∧

Find out more about our Weight Management Plan


What your BMI result means

A BMI score of over 30 is classed as ‘obese’.

This category of BMI is associated with a higher risk of health conditions, such as heart disease, high blood pressure, cancer and type 2 diabetes.

Healthy weight loss

If you want to lose weight, a good approach is to reduce your calorie intake by around 600 calories per day. This can be achieved by reducing high calorie foods such as sugar sweetened drinks, and ultra processed foods such as biscuits and crisps. Consuming plenty of fibre and protein will keep you fuller for longer and help to prevent overeating. Managing stress and sleeping well can also make it easier to eat well. Increasing your physical activity has many benefits and can help you to use more energy each day.

Healthy eating

A balanced, nutritious diet is essential for healthy growth and to enable your body to function properly.

Read more

What is a healthy weight for adults?

Although being overweight can cause health problems, it’s important to remember that being underweight can too.

Show more

Obesity in adults

Being obese increases your risk of serious health conditions, so it’s important to think about whether you’re ready to lose weight.

Read more

Bupa Weight Management Plan

The Bupa weight management plan is designed for people with a BMI over 30 (or over 27 if you have a weight related condition). The plan is designed to empower you to achieve and maintain a healthy weight in a sustainable way.

To book or to make an enquiry, call us on 03452660566∧

Find out more about our Weight Management Plan


BMI readings are useful for many people, but they may not be right for everyone.

BMI measurements might not be helpful if:

  • You are of older age. This is because as you age you usually gain body fat and lose muscle. The BMI measurement can underestimate your body fat, making results unreliable for this age group.
  • You are very athletic or muscly. This may lead to a high BMI reading, even if your total body fat is very low.
  • You’re a child or teenager. Girls and boys develop differently and have different amounts of body fat at different ages. Therefore, a child aged between 2 and 17 should use a centile BMI chart. This compares their data to other children of the same age.
  • You’re pregnant. Going into a pregnancy with a healthy weight is important, but as you gain weight during pregnancy, the BMI reading is less useful.
  • You’re from a Black and Asian background. Your healthy BMI level will be lower, so speak to a GP for more information.

How healthy are you?

With our health assessments you get an action plan that’s tailor-made for you.

To book or to make an enquiry, call us on 0370 218 8122

Find out more about our health assessments

Reviewed by Julia Ebbens, Bupa Health Content Editor March 2024
Expert reviewer, Niamh Hennessy, Lead Dietitian, Cromwell Hospital
Next review due March 2027

  • Body mass index – BMI. World Health Organization. euro.who.int, accessed 22 April 2024
  • Obesity: identification, assessment and management. National Institute for Health & Care Excellence. nice.org.uk, accessed 22 April 2024.
  • A healthy balanced diet. British Nutritional Foundation. Nutrition.org.uk, accessed 22 April 2024.
  • Bone health checklist. The Royal Osteoporosis Society. theros.org.uk, accessed 22 April 2024
  • Underweight and fertility when planning a pregnancy. Tommy’s. www.tommys.org, updated 19 August 2023.
  • Healthy snacks: Food Fact Sheet. British Dietetic Association. www.bda.uk.com, updated January 2022
  • Help and Treatment. Beat. www.beateatingdisorders.org.uk, accessed 22 April 2024
  • Health matters: obesity and the food environment. Public Health England. www.gov.uk, published 31 March 2017
  • Macronutrients and energy balance. Oxford Handbook of Nutrition and Dietetics (3 ed). Oxford Medicine Online. www.oxfordmedicine.com, April 2020
  • UK Chief Medical Officers' Physical Activity Guidelines. Department of Health and Social Care. www.gov.uk, published 7 September 2019
  • Macronutrients and energy balance. Oxford Handbook of Nutrition and Dietetics (3 ed). Oxford Medicine Online. www.oxfordmedicine.com, April 2020
  • UK Chief Medical Officers' Physical Activity Guidelines. Department of Health and Social Care. www.gov.uk, published 7 September 2019
  • Body Mass Index: Considerations for Practitioners. Centers for Disease Control and Prevention. www.cdc.gov, accessed 24 April 2024
  • Weight management before, during and after pregnancy. National Institute for Health & Care Excellence. www.nice.org.uk, accessed 22 April 2024
  • Ríos-Prego M, Anibarro L, Sánchez-Sobrino P. Relationship between thyroid dysfunction and body weight: a not so evident paradigm. Int J Gen Med. 2019 Aug;12:299-304. doi: 10.2147/IJGM.S206983.
  • Depression signs and symptoms. Mind UK. mind.org.uk, accessed 24 April 2024.
  • Poti JM, Braga B, Qin B. Ultra-processed Food Intake and Obesity: What Really Matters for Health-Processing or Nutrient Content? Curr Obes Rep. 2017 Dec;(4):420-431. doi: 10.1007/s13679-017-0285-4.
  • Calorie counting. NHS. Nhs.uk, accessed 22 April 2024.
  • Fibre. British association of dietitians.bda.uk.com, last reviewed April 2021.
  • Razzoli M, Pearson C, Crow S, Bartolomucci A. Stress, overeating, and obesity: Insights from human studies and preclinical models. Neurosci Biobehav Rev. 2017 May;76(Pt A):154-162. doi: 10.1016/j.neubiorev.2017.01.026.
  • Kline, C.E., Chasens, E.R., Bizhanova, Z. et al. The association between sleep health and weight change during a 12-month behavioral weight loss intervention. Int J Obes 45, 639–649 (2021). https://doi.org/10.1038/s41366-020-00728-8

This information was published by Bupa's Health Content Team and is based on reputable sources of medical evidence. It has been reviewed by appropriate medical or clinical professionals and deemed accurate on the date of review. Photos are only for illustrative purposes and do not reflect every presentation of a condition.

Any information about a treatment or procedure is generic, and does not necessarily describe that treatment or procedure as delivered by Bupa or its associated providers.

The information contained on this page and in any third party websites referred to on this page is not intended nor implied to be a substitute for professional medical advice nor is it intended to be for medical diagnosis or treatment. Third party websites are not owned or controlled by Bupa and any individual may be able to access and post messages on them. Bupa is not responsible for the content or availability of these third party websites. We do not accept advertising on this page.

The Patient Information Forum tick


Our information has been awarded the PIF tick for trustworthy health information.

Content is loading