ArtsAutosBooksBusinessEducationEntertainmentFamilyFashionFoodGamesGenderHealthHolidaysHomeHubPagesPersonal FinancePetsPoliticsReligionSportsTechnologyTravel

How to Calculate your Body Mass Index (BMI)

Updated on September 12, 2014

Your Body Mass Index (BMI) is a number computed based on your weight and height. Invented in the early 1800's, the BMI is a mathematical tool used by doctors to assess the health risks of a particular person of interest. Today, you can use the information to determine where you stand within the commonly accepted range of healthy and unhealthy weights. Typically the higher your BMI is, the higher your risk is for being diagnosed with some of the various obesity related diseases plaguing the world. These diseases include, but are not limited to, diabetes, hypertension, and heart disease.

BMI Formulas

The formula to determine your body mass index is pretty simple. Your BMI is equal to your mass divided by the square of your height. Of course the units of which you measure your height and weight does matter. If you are measuring your height in meters and your mass in kilograms, the formula is simply:

If you are measuring your height in inches and your weight in pounds, the formula becomes:

If you are weary of using formulas you can use this neat online calculator or the chart below instead.

This chart is based on the latest categories from the World Health Organization
This chart is based on the latest categories from the World Health Organization | Source

BMI Categories

The BMI has been divided into 4 categories (some countries use 6 categories) based on numerous studies of risk factors for obesity related diseases.

Below 18.5
18.5 - 24.9
25.0 - 29.9
30.0 and Above

Note that what is considered normal, underweight, or obese may differ from country to country. The above table is for the USA. When determining the BMI for children (younger than 18) this table should not be used. Typically a doctor will compare the BMI number with those of other children in the same age group. A child may be considered underweight or obese if they rank below the 5th percentile or above the 95th percentile.

Limitations of the Body Mass Index

Many of you out there would probably agree that the number computed from these formulas does not adequately represent everyone in every case. For example, athletes could be considered obese based on the BMI even though they may actually have a really low body fat percentage. The BMI also has problems when it comes to assessing the health risks of the elderly because these individuals have typically lost considerable amounts of muscle mass. Caution should be used when the BMI calculation is applied in either of these cases. In addition to this, the BMI does not account for the many different body shapes and bone structures that people in this world have. Because of these limitations, the BMI should always be used in conjunction with other methods of health risk assessment such as the waist and neck circumference or body fat percentage.

Does BMI Matter?

The really is no easy answer to this questions. Many doctors today still use the BMI as an indicator of someone's overall health. However, as we have seen, the BMI does not tell the whole story. There are certainly many other things, such as lung capacity and body fat percentage, that are also just as important. So if your BMI says that you are obese I wouldn't worry about it so much. Again, the BMI is an indicator and not the holy grail of body numbers. After all, the human body is complicated and our species has a wide variety of traits. No single number or formula can tell you everything that you need to know about your health.


    0 of 8192 characters used
    Post Comment
    • profile image

      personal training Norwich 

      6 years ago

      How can you calculate your body mass index? My brother keeps complaining about her weight. I know that he is just right but I need a way of proving it. And I herd about body mass index can anyone tell me how it works??

    • CWanamaker profile imageAUTHOR

      Christopher Wanamaker 

      8 years ago from Arizona

      @kerlynb - I am glad you found this useful. This hub is also useful for me. I learned a few new thinks while researching the content for this.

      @abhipsitabose - Thanks and will do!

    • abhipsitabose profile image


      8 years ago from India

      useful do check out my hub .....this is for the underweight..very helpful

    • kerlynb profile image


      8 years ago from Philippines, Southeast Asia, Earth ^_^

      Voted your hub useful. I do check my BMI on the net (there are lots of websites that offer free, quick, and accurate calculations)every now and then. I'm actually quite conscious about my health. While some people do not like BMI as a gauge, I personally find it very good in making my self strive for a better shape. When I see my BMI heading towards 20s, my alarm bell rings :)


    This website uses cookies

    As a user in the EEA, your approval is needed on a few things. To provide a better website experience, uses cookies (and other similar technologies) and may collect, process, and share personal data. Please choose which areas of our service you consent to our doing so.

    For more information on managing or withdrawing consents and how we handle data, visit our Privacy Policy at:

    Show Details
    HubPages Device IDThis is used to identify particular browsers or devices when the access the service, and is used for security reasons.
    LoginThis is necessary to sign in to the HubPages Service.
    Google RecaptchaThis is used to prevent bots and spam. (Privacy Policy)
    AkismetThis is used to detect comment spam. (Privacy Policy)
    HubPages Google AnalyticsThis is used to provide data on traffic to our website, all personally identifyable data is anonymized. (Privacy Policy)
    HubPages Traffic PixelThis is used to collect data on traffic to articles and other pages on our site. Unless you are signed in to a HubPages account, all personally identifiable information is anonymized.
    Amazon Web ServicesThis is a cloud services platform that we used to host our service. (Privacy Policy)
    CloudflareThis is a cloud CDN service that we use to efficiently deliver files required for our service to operate such as javascript, cascading style sheets, images, and videos. (Privacy Policy)
    Google Hosted LibrariesJavascript software libraries such as jQuery are loaded at endpoints on the or domains, for performance and efficiency reasons. (Privacy Policy)
    Google Custom SearchThis is feature allows you to search the site. (Privacy Policy)
    Google MapsSome articles have Google Maps embedded in them. (Privacy Policy)
    Google ChartsThis is used to display charts and graphs on articles and the author center. (Privacy Policy)
    Google AdSense Host APIThis service allows you to sign up for or associate a Google AdSense account with HubPages, so that you can earn money from ads on your articles. No data is shared unless you engage with this feature. (Privacy Policy)
    Google YouTubeSome articles have YouTube videos embedded in them. (Privacy Policy)
    VimeoSome articles have Vimeo videos embedded in them. (Privacy Policy)
    PaypalThis is used for a registered author who enrolls in the HubPages Earnings program and requests to be paid via PayPal. No data is shared with Paypal unless you engage with this feature. (Privacy Policy)
    Facebook LoginYou can use this to streamline signing up for, or signing in to your Hubpages account. No data is shared with Facebook unless you engage with this feature. (Privacy Policy)
    MavenThis supports the Maven widget and search functionality. (Privacy Policy)
    Google AdSenseThis is an ad network. (Privacy Policy)
    Google DoubleClickGoogle provides ad serving technology and runs an ad network. (Privacy Policy)
    Index ExchangeThis is an ad network. (Privacy Policy)
    SovrnThis is an ad network. (Privacy Policy)
    Facebook AdsThis is an ad network. (Privacy Policy)
    Amazon Unified Ad MarketplaceThis is an ad network. (Privacy Policy)
    AppNexusThis is an ad network. (Privacy Policy)
    OpenxThis is an ad network. (Privacy Policy)
    Rubicon ProjectThis is an ad network. (Privacy Policy)
    TripleLiftThis is an ad network. (Privacy Policy)
    Say MediaWe partner with Say Media to deliver ad campaigns on our sites. (Privacy Policy)
    Remarketing PixelsWe may use remarketing pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to advertise the HubPages Service to people that have visited our sites.
    Conversion Tracking PixelsWe may use conversion tracking pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to identify when an advertisement has successfully resulted in the desired action, such as signing up for the HubPages Service or publishing an article on the HubPages Service.
    Author Google AnalyticsThis is used to provide traffic data and reports to the authors of articles on the HubPages Service. (Privacy Policy)
    ComscoreComScore is a media measurement and analytics company providing marketing data and analytics to enterprises, media and advertising agencies, and publishers. Non-consent will result in ComScore only processing obfuscated personal data. (Privacy Policy)
    Amazon Tracking PixelSome articles display amazon products as part of the Amazon Affiliate program, this pixel provides traffic statistics for those products (Privacy Policy)
    ClickscoThis is a data management platform studying reader behavior (Privacy Policy)