Wix Restaurants charges the same add-on price whether a pizza is small or large, and it’s been a common request to charge more for toppings on bigger sizes (e.g. +$1 on a Large).
Truth be told, I didn’t realize Wix had ways to make customizable apps for websites. I thought that was really cool and decided to see what I could do.
I built a small app that does this: you set a per-size upcharge for an add-on group (like Toppings), and the difference is added automatically at checkout and shows on the order. Customers order exactly as before. It works for pizzas, subs, bowls or anything with sizes and add-ons.
It’s free for one add-on group: Size Pricing for Restaurants | Wix App Market | Wix.com
Happy to answer questions, and feedback is very welcome.