Kitting is the process of bundling separate SKUs into a single, ready-to-ship unit with its own SKU. Instead of picking five items off five different shelves every time an order comes in, you pre-build the bundle once and pick it as one. It saves pick time, cuts errors, and gives marketing something cleaner to sell.
In practical terms, kitting means you take items A, B, C, and D out of regular stock, pack them together, and create a new parent SKU — call it KIT-001. From that moment, KIT-001 is what your warehouse picks, your shipping label points at, and your customer receives.
Example: a coffee subscription box. The components are one 250g bag of beans (SKU BEAN-ETH), one branded mug (SKU MUG-WH), one recipe card (SKU CARD-01), and a kraft box (SKU BOX-M). On its own, none of that ships. As KIT-COFFEE-MAR, it ships 1,200 times in March. You decrement four child SKUs and one box per kit built.
People mix these up constantly, so here's the clean line.
A bill of materials (BOM) is a list. It says "to make one finished product, you need these parts in these quantities." It's a document.
Assembly is what manufacturing does with a BOM — taking raw materials, applying labor, and producing something materially different. A bicycle frame plus wheels plus a chain becomes a bicycle. The output isn't reversible without tools.
Kitting sits between the two. You're following something that looks like a BOM, but you're not transforming the items. You're just grouping them. Tear the shrink wrap off a hardware kit and you've got the same screws, brackets, and washers you started with.
That distinction matters for accounting. Assembled goods often need labor and overhead in their cost. Kits usually just roll up component cost plus packaging. Many bill of materials systems support both — flag the parent as a kit vs a manufactured item so cost rolls up correctly.
You've got two choices on timing.
Pre-kitting means you build the kits up front and stock them as finished goods. Good when demand is predictable, components are stable, and pick speed matters. A subscription box company pre-kits the entire month's run on the 25th.
On-demand kitting (sometimes called pick-to-order kitting) means you assemble the kit only when an order lands. Good when components are expensive, demand is lumpy, or customers personalize the contents. A B2B promo company kitting branded swag for a specific client event does it on demand.
The tradeoff is obvious. Pre-kitting locks inventory into a parent SKU you might not sell. On-demand kitting adds 30–90 seconds to every order pick. Most operations end up doing both — pre-kit your top sellers, build the long tail on demand.
Three traps catch most teams.
Over-committing components. Pre-kit too aggressively and you've buried a component SKU inside a parent that isn't moving. If MUG-WH is also sold solo, every mug locked in KIT-COFFEE-MAR is one you can't sell on its own.
Demand misforecast. Build 2,000 kits, sell 800, and you've got 1,200 units of finished goods that need un-kitting. That's labor you didn't plan for.
Traceability gaps. When a component gets recalled — a contaminated ingredient, a defective part — you need to know which kits it ended up in. If your system tracks the kit as one opaque SKU and forgets the components, the recall blows up. Make sure your inventory tool keeps component lot/serial visibility on every kit built.
StockZip handles kit parent SKUs with component decrement built in — build a kit and the child SKUs drop automatically. Start a free trial or read the deeper bill of materials walkthrough if you're setting up your first kit structure.
Straight answers about spreadsheets, scanners, offline work, existing systems, and the free period.
No. A BOM is the recipe; kitting is the act of grouping items per that recipe. A kit usually has a BOM behind it, but a BOM by itself doesn’t mean you’re kitting — it might be feeding a full assembly process instead.