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.
Calculate your BMI
What your BMI result means
You’re in the underweight range, with a BMI score of under 18.5.
If you’re underweight, you may not be getting all the nutrients that your body needs. Different nutrients come from different foods; some give you energy and others help your body to grow, repair itself and function properly. Being underweight is sometimes associated with health conditions such as osteoporosis and fertility problems.
Your weight is determined by lots of factors. This includes how much energy (calories) you consume through food and how much energy your body uses. Aim for three balanced mealsa day, making sure you eat enough carbohydrates and protein, with some healthy, nutrient-dense snacks in between. Good examples of nutrient-dense snacks include a handful of unsalted nuts, a pot of yogurt or peanut butter on toast. Talk to your practice nurse or GP for more advice. You may also be referred to a dietitian.
If your GP has any concerns about your health or wants to explore potential reasons for your weight loss, they may refer you for further tests or investigation. If you suffer with an eating disorder, your nurse or GP will be able to support you to gain the right treatment.
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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 healthy weight and type 2 diabetes. Try to eat a healthy diet that is lower in fat and sugar and includes plenty of fruits and vegetables. We should also all aim to do some physical activity, ideally around 30 minutes a day on five days a week.
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Doing regular exercise is great for keeping your weight under control, and can boost your mental as well as physical health.
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Keeping eye on your weight and making sure it stays within a healthy range, will reduce your risk of numerous health problems.
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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.
Your weight is determined by lots of factors. This includes how much energy (calories) you consume through food and how much energy your body uses. Try to eat a healthy balanced diet and get some exercise.
A healthy diet should include plenty of fruits and vegetables and be lower in fat and sugar. We should also all aim to do some physical activity, ideally around 30 minutes a day on five days a week. If you’ve not done much exercise before, you can start small. Consider walking to the shops instead of taking the car or use your lunch break to get outside and stretch your legs. Talk to a doctor or a dietitian for advice and more information.
Healthy eating
A balanced, nutritious diet is essential for healthy growth and to enable your body to function properly.
Healthy weight for adults
Although being overweight can cause health problems, it’s important to remember that being underweight can too.
Learn more
Portion sizes
Eating too much or too little of any of the major food groups can be bad for your health.
Learn more
Losing weight safely
Increasing how active you are and watching how much and what you eat are key for losing weight healthily.
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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.
Your weight is determined by lots of factors. This includes how much energy (calories) you consume through food and how much energy your body uses. Try to eat a healthy balanced diet and get some exercise.
A healthy diet should include plenty of fruits and vegetables and be lower in fat and sugar. We should also all aim to do some physical activity, ideally around 30 minutes a day on five days a week. If you’ve not done much exercise before, you can start small. Consider walking to the shops instead of taking the car or use your lunch break to get outside and stretch your legs. Talk to a doctor or a dietitian for advice and more information.
Healthy eating
A balanced, nutritious diet is essential for healthy growth and to enable your body to function properly.
Healthy weight for adults
Although being overweight can cause health problems, it’s important to remember that being underweight can too.
Read more
Portion sizes
Eating too much or too little of any of the major food groups can be bad for your health.
Show more
Losing weight safely
Setting yourself targets for slow, steady weight loss is the way to go rather than dramatic crash dieting.
View more
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Advice on some well-known fad diets and whether they can help you eat more healthily.
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Limitations of BMI Limitations of BMI
Although, in general, BMI is a useful measure of whether or not you’re a healthy weight, it isn’t suitable for everyone. There are some groups of people where a BMI result should be considered carefully, or where it may not even be helpful to use at all.
- Girls and boys develop differently and have different amounts of body fat at different ages. Therefore, a child’s age and sex are taken into account when looking at their BMI.
- As we age, we tend to have more body fat and less muscle, so BMI may underestimate body fat in older people.
- Athletes and people with a lot of muscle may have a high BMI but actually not have much body fat.
- Pregnant women gain weight as a result of their developing baby. However, it’s still preferable to have a healthy BMI before becoming pregnant to reduce health risks to both you and your developing baby.
- People from certain Black and Asian backgrounds are at risk of certain health problems at a lower BMI than others. Speak to your GP or practice nurse for more information.
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Sources Sources
- Body mass index – BMI. World Health Organization. www.euro.who.int, accessed 09 March 2021
- Obesity: identification, assessment and management. National Institute for Health & Care Excellence. www.nice.org.uk, published 27 November 2014
- Healthy Eating: Food Fact Sheet. British Dietetic Association. www.bda.uk.com, updated August 2020
- Bone health checklist. The Royal Osteoporosis Society. www.theros.org.uk, accessed 09 March 2021
- Underweight and fertility when planning a pregnancy. Tommy’s. www.tommys.org, updated 05 June 2018
- Healthy snacks: Food Fact Sheet. British Dietetic Association. www.bda.uk.com, updated September 2018
- Help and Treatment. Beat. www.beateatingdisorders.org.uk, last updated December 2020
- 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 (3rd 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 09 March 2021
- Weight management before, during and after pregnancy. National Institute for Health & Care Excellence. www.nice.org.uk, published 28 July 2010
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Author information Author information
Reviewed by Abbey Stanford, Specialist Heath Editor, Bupa Health Content Team, March 2021
Expert reviewer, Niamh Hennessy, Lead Dietitian, Cromwell Hospital
Next review due March 2024
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FAQs
What is the formula for BMI UK? ›
Calculating your BMI
The BMI calculation divides an adult's weight in kilograms (kg) by their height in metres (m) squared. For example, an adult who weighs 70 kg (around 11 stone) and whose height is 1.75 m will have a BMI of 22.9.
According to the BMI weight status categories, anyone with a BMI between 25 and 29.9 would be classified as overweight and anyone with a BMI over 30 would be classified as having obesity. However, athletes may have a high BMI because of increased muscularity rather than increased body fatness.
What is a good BMI for my age? ›18.5 to 24.9 - you have a healthy weight range for young and middle-aged adults. 25.0 to 29.9 - you are overweight. Over 30 - you are obese.
What is normal BMI for adults UK? ›BMI ranges
between 18.5 and 24.9 – This is described as the 'healthy range'. between 25 and 29.9 – This is described as overweight. between 30 and 39.9 – This is described as obesity. 40 or over – This is described as severe obesity.
Formula: weight (lb) / [height (in)]2 x 703
When using English measurements, ounces (oz) and fractions must be changed to decimal values. Then, calculate BMI by dividing weight in pounds (lb) by height in inches (in) squared and multiplying by a conversion factor of 703.
With the metric system, the formula for BMI is weight in kilograms divided by height in meters squared. Since height is commonly measured in centimeters, an alternate calculation formula, dividing the weight in kilograms by the height in centimeters squared, and then multiplying the result by 10,000, can be used.
Does a BMI of 30 always indicate obesity? ›If your BMI is less than 18.5, it falls within the underweight range. If your BMI is 18.5 to <25, it falls within the healthy weight range. If your BMI is 25.0 to <30, it falls within the overweight range. If your BMI is 30.0 or higher, it falls within the obesity range.
How many pounds is a BMI of 25? ›This table shows us that a woman who is 5 ft. 4 in. tall is considered overweight (BMI is 25 to 29) if she weighs between about 145 and 169 pounds. She is considered obese (BMI is 30 or more) if she is closer to 174 pounds or more.
What is overweight BMI 27 to 25? ›A healthy weight is considered to be a BMI of 24 or less. A BMI of 25 to 29.9 is considered overweight. A BMI of 30 and above is considered obese.
What is a good BMI for 70 year old? ›Older people.
In older adults it is often better to have a BMI of 25 to 27, rather than under 25. If you are older than 65, for example, a slightly higher BMI may help protect you from thinning of the bones (osteoporosis).
Does your age matter in BMI? ›
But it's only one measure and doesn't tell the whole story. For example, BMI doesn't take into consideration your age, sex, or muscle mass, which are all important when it comes to finding your ideal weight. Older adults tend to lose muscle and bone, so more of their body weight is likely to come from fat.
How much should a 5 5 female weigh? ›| Height | Weight | |
|---|---|---|
| 5' 4" | 110 to 144 lbs. | 145 to 173 lbs. |
| 5' 5" | 114 to 149 lbs. | 150 to 179 lbs. |
| 5' 6" | 118 to 154 lbs. | 155 to 185 lbs. |
| 5' 7" | 121 to 158 lbs. | 159 to 190 lbs. |
below 18.5 – you're in the underweight range. between 18.5 and 24.9 – you're in the healthy weight range. between 25 and 29.9 – you're in the overweight range. 30 or over – you're in the obese range.
Does body frame size affect BMI? ›Body frame size is not used when calculating BMI; instead, you can figure out your BMI using your height and weight. The BMI measurement does not take into account body composition or sex differences, so its accuracy is debatable.
What size should I be for my height and weight? ›| Height | Normal weight BMI 19–24 | Overweight BMI 25–29 |
|---|---|---|
| 5 ft 2 in (62 in) | 104–131 lb | 136–158 lb |
| 5 ft 3 in (63 in) | 107–135 lb | 141–163 lb |
| 5 ft 4 in (64 in) | 110–140 lb | 145–169 lb |
| 5 ft 5 in (65 in) | 114–144 lb | 150–174 lb |
Body Mass Index is a simple calculation using a person's height and weight. The formula is BMI = kg/m2 where kg is a person's weight in kilograms and m2 is their height in metres squared. A BMI of 25.0 or more is overweight, while the healthy range is 18.5 to 24.9.
What is the normal BMI for female? ›Body mass index (BMI) relates weight to height in a normalized index that was first published in Quetelet's 18th Century treatise on 'the average man'. BMI is defined as weight (in kilograms) divided by height (in metres) squared.
What is the official BMI formula? ›Body Mass Index (or BMI) is calculated as your weight (in kilograms) divided by the square of your height (in metres) or BMI = Kg/M2.
How to measure BMI without a scale? ›Tape measure.
Men: 64 - (20 x height/waist circumference) = RFM. Women: 76 - (20 x height/waist circumference) = RFM.
What is the original formula for BMI? ›
It's a simple formula: weight in kilograms divided by height in metres squared and voila, you have your body mass index — a two-digit figure that slots you into a handful of equally clear-cut boxes.
Why does my BMI say I'm overweight when I'm not? ›BMI doesn't account for body composition, which means it misses the difference between muscle mass and fat. Because muscles are more dense and heavier than fat, bodybuilders and other professional athletes like football players are often considered obese or overweight based on their BMI alone.
Why is my BMI so high but I'm not fat? ›How muscular you are: A few people have high BMIs but don't have much body fat. Their muscle tissue pushes up their weight. An example: "A football player or a body builder who is very muscular. Their BMI shows up pretty high, and yet their body fat is actually pretty low," Kahan says.
Can I be overweight on the BMI and still healthy? ›Is it possible to be overweight and healthy? Silvana Pannain, MD: Yes, you can be overweight and metabolically healthy. At the same time, we know that obesity is a disease that affects the body in many different ways. Thirteen types of cancer and 200 other health conditions are related to obesity.
What foods lower your BMI? ›- Whole grains (whole wheat, steel cut oats, brown rice, quinoa)
- Vegetables (a colorful variety-not potatoes)
- Whole fruits (not fruit juices)
- Nuts, seeds, beans, and other healthful sources of protein (fish and poultry)
- Plant oils (olive and other vegetable oils)
The more weight lost, the more blood pressure can drop. As you lose weight, it may be possible to reduce your dose of blood pressure medication — or stop taking blood pressure medication completely. Never make changes to your blood pressure medication on your own, however. Talk to your health care provider first.
How much should I walk if my BMI is 30? ›How much should I walk if my BMI is 30? We recommend walking 10,000 steps or 90 minutes a day if you fall into BMI's “overweight” category. The good news is, within the year, you can move into the “healthy” weight bracket by walking an hour and a half a day.
What is the exact formula of BMI? ›The formula for BMI is weight in kilograms divided by height in meters squared. If height has been measured in centimeters, divide by 100 to convert this to meters. When using English measurements, pounds should be divided by inches squared.
What is the new formula to measure BMI? ›April 20, 2023 Body Mass Index (BMI) Calculator
Body Mass Index is a simple calculation using a person's height and weight. The formula is BMI = kg/m2 where kg is a person's weight in kilograms and m2 is their height in metres squared. A BMI of 25.0 or more is overweight, while the healthy range is 18.5 to 24.9.