i need a mobile app that can calculate

I need an Android app. I would like it designed and built.

I want to build a free macronutrient calculator to collect emails. I want it to be simple and easy to use for end-users. Below are a few examples of the content and fields I'd like in the app

https://legionathletics.com/tools/macronutrient-calculator/
https://www.transparentlabs.com/pages/calculator

Thank you!