Here is my GUI program for calculating total loan amount and monthly pay, i have attached my github repo link where you can able to find the source code and executable file. You can simply download the executable file and open it to run the application. IF you like it then do share and follow my github repo for user friendly tutorials and program. Any suggestion or quires pls do comment.

https://github.com/Ajay2521/Python-Projects/tree/master/Loan-Calculator

Here is some snap of it: