Calculated fields in new Feature

I’m looking at building an ROI Feature that would take details from the item page (servings per unit from a custom field) and sell price etc and build recipes with them which would then be used to create menus per customer offering them a customized ROI based on the their menu. The trouble is I need a a way to get the cost per serving. I can calculate it fine on a page but that doesn’t translate into usage on a feature. Is there a way to do a calculated field somewhere in line (could be on the item card, or within the recipe or somewhere else if it makes sense).