here we review cost calculator modules for wordpress.
TIP : try one of these plugins, then go ahead with gravity forms hacks and code based calculation
- https://www.wordpress-estimation-payment-forms.com/ is a multi step form with final calculation step, while stylemixtheme below sells a module that delivers instant calculation
- another one from codecanyon has embedded lead generation tool https://codecanyon.net/item/cost-calculator-wordpress-plugin/12778927 and this one has its own database integration https://codecanyon.net/item/cost-calculator-for-wordpress/21709867. Free version is quite easy to test and use as a prototyping tool
- don't bother wasting time on this free to try plugin , its interface is useless. https://wordpress.org/plugins/stylish-cost-calculator/
- currently trying Calculated Fields Form : it has a better interface but requires a lot of mind bending calculation to get the stuff to work