# Bill of materials A bill of materials is the answer to "what does this actually take to build?" Set once per product, then read automatically every time it sells. For a furniture piece or a bike, that might be a frame, a set of legs, hardware, and a finish. Orderkraft explodes that list into the manufacturing order the moment the order lands, in the right quantities, so nothing gets allocated by hand and nothing gets forgotten. Production time and dock-to-stock time live on the bill of materials too, which is what makes the lead time on your product page real instead of a guess. Change the BOM, and every lead time reading from it updates with it. It's built for real assemblies, not a flat parts list: an input on a bill of materials can itself be a component with its own bill of materials, so a sub-assembly gets defined once and reused across every finished good that needs it. ## Questions **What can a bill of materials be made from?** Raw materials, components, or even other products and their variants. A BOM can nest, so a finished piece of furniture can be built from sub-assemblies that each have their own bill of materials. **Does this replace an inventory system?** No. It tracks what a made-to-order product consumes to get built, not general warehouse stock. Orderkraft is deliberately not a WMS. **What happens if I change a product's bill of materials?** New orders use the updated version. Manufacturing orders already in progress keep the materials they were created with, so a mid-week spec change doesn't rewrite work that's already underway.