This WordPress plugin can be used to add a block which will calculate your Basal Metabolic Rate (BMR) and will tell you how many calories you should take in the entire day based on age, gender, weight, height, how much activity you do in an entire day, calculation formula.
This plugin also contains an about section where you can read what is Basal Metabolic Rate.

1. You can change the Measurement Units of height and weight using a toggle switch. 
2. You can enter weight in Kilograms(Kg) or pounds (lbs)
3. You can enter height in either centimeters (cm) or in Feet & Inches
4. You can select/ change the gender using a toggle switch
5. You can select your activity level among 5 given choices in the dropdown and select which suits you best
6. You need to enter your age in years
7. You need to select the calculation formula.
8. There is proper validation so no one can enter anything that makes the calculation of BMR impossible which includes empty fields of height, weight, age or if you put any characters in age, weight or height. 

Wordpress 4.5+

How To Install?
1. After going to the backend of your site, go to Plugins >> Add New 
2. Now, you will see an upload plugin button on the top, click that button and
select the zip file provided to you.
3. Then, click on Install Now and Activate the plugin.

How To Use?
Just use the shortcode [aj_bmr_calculator] wherever in the content of a Post or Page
or any custom post type you want to add the calculator.

ChangeLog  

1.0 Initial release of the plugin