QUESTION Calculation form

[Timbow]

Cuirassier - I don't know for sure and I couldn't recommend any particular site but if you are not 100% confident with the html and php of forms and data submission I think you can go to an online service which will help build the form and handle the data. Maybe one to build the form, or an opensource template like:
https://css-tricks.com/multi-product-qua...rder-form/
and another to email you the result like:
https://www.briskforms.com/

Maybe even for free.