will do this calculation (BMI) for you as per your need, for each platform (ios/android/window) etc.. our development cost is $250.00, please provide your messenger id will discuss about project and start work together from tomorrow here (if you select us in freelancer).
Assumption:
a) will create design based on your input
b) there are only one langauge (english)
c) app having only one orientation and support only smart phone
d) there are no advertisement or payment process
e) there are no social network or 3rd party api integration