I have been reading up on Gravity Forms and it seems the most spoken about and stable product, but before I purchase it for a specific website, I would like to know if it can do a function as designed on jsFiddle.
http://jsfiddle.net/Tobievr/9Dj3j/140/embedded/result/
This is a function that works out surface area of rooms, less doors and windows and gives an answer on the same page for further calculations.
Thanks
Tobie