Calculate formulare

Hello,
I´m lokking for to create an calculate formulare like this: https://bullibattery.de/wp-content/uploads/2020/03/Screenshot-2020-03-30-20.11.45.png. Can you please help me to find a god, easy an cheap plugin to do that. If you want, you can take a look to my backend, may i already have some plugins to fix that. Thank you

Hi Andi ,
I would like to share my custom developed script to achieve the functionality.

Thanks
Deep