WatchBMI: A BMI Calculator App written by Dr. Nachbar

WatchBMI is an app written by Dr. Nachbar using the Swift programming language in Xcode to run on the Apple Watch.

It allows you to easily calculate Body Mass Index (BMI), a standard measure of the relationship between height and weight, on the watch.

It is available now on the Apple Watch - go to the App Store on your iPhone and search for "WatchBMI". Only $0.99!

It may install on the watch when you purchase it in the App Store, but if not, go to the App Store app on the watch itself, scroll to the bottom to "Account" and click on that, then click on "Purchased" to see and install the app.

To upgrade to a newer version, after upgrading on your iPhone, you may need to manually delete the app on the watch (from the app screen, long-press the icon until they start vibrating, then tap the icon of the app you want to remove, then go to the App Store app on the watch, find Account, and find Purchased.)

I wrote the app because I often have to calculate BMI when I am seeing a patient, and I don't want to have to take out and unlock my phone while I am talking to a patient.

You can enter height and weight either in metric or imperial units, and switch between them.

While it will certainly work for an individual to determine her own BMI, it is targeted at users (such as myself) who need to calculate BMI based on the measurements of multiple individuals.  

It does report the CDC category of the BMI, but does not otherwise interpret any of the data.  It does not store or collect any of the entered information.

You should know that BMI is only a reflection of height and weight; it does not assess body composition, or differentiate between fat and muscle.

Instructions:

Simply click on one of the buttons on the main screen to show a keyboard for entering the value.  

WatchBMI can accept values in either the Metric or the Imperial system.  Click the "M" button to change to metric, click the "I" button to change to imperial

If Imperial:

Click on "Pounds" to enter the weight in pounds.  

Use the "Back" button to go back to the main screen.  

Click on "Feet" to enter the feet part of height.  

Click on "Inches" to enter the inches part of height.  

If Metric:

Click on "Kilos:" to enter the weight in kilograms.

Click on "Cms: to enter the height in centimeters.

The app does not allow inches greater than 11, feet greater than 7, or weight greater than 999, with similar maximums in metric.

Once all three values have been entered, the main screen (again, click the "Back" button) to show the calculated BMI and the CDC category for that BMI.

When changing from Imperial to Metric or Metric to Imperial, the height and weight will change as well, so you can enter weight in kilograms and height in feet and inches.

Reference Information:

Information from the U.S. Centers for Disease Control and Prevention (CDC) provides information about BMI and its appropriate use at https://cdc.gov/bmi  

BMI is a measure of weight relative to height. 

According to CDC at https://cdc.gov/bmi/about/index.html :  BMI is a quick, low-cost, and re  liable screening measure for underweight, overweight, or obesity; BMI is a valuable population health measure used worldwide; for individuals, BMI should be considered with other factors, such as blood pressure, cholesterol levels, and physical examination.

The CDC Adult BMI Categories are from https://cdc.gov/bmi/adult-calculator/bmi-categories.html.  

BMI and this app does not diagnose or treat any condition.  The CDC BMI Categories calculated by this app are designed for adults 20 and older, and do not apply to children.

Check with your doctor before using this app or making any medical decisions based on BMI.  

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