I need a code to convert pounds to kilograms on Adobe Acrobat Pro

Hello, I need to convert pounds to kilgrams in Adobe Acrobat Pro.

I have two text fileds, one that reads "Wt lbs" and another that reads "Wt kg". What I would like is when I enter the pound under "Wt lbs" it automatically converts to kilograms under "Wt kg".

Something similar to calculating a person age through a DOB field, which I already have done using a code. All I need is a code, as I do not know how to do them and where do I put this code.

Thank you!