An Introduction to Kitting

Many people unknowingly have their first interaction with a kitted group of products at a very young age. A small splinter, a skinned knee, or some other minor childhood mishap results in an appearance by the dreaded first aid kit. 

Kitting is combining several stock items into one sellable unit with its own SKU, so the group is picked, sold, and counted as a single product. It differs from bundling, where the items keep their own SKUs and are grouped only at the point of sale. The hard part is not assembling a kit. It is that a kit's available quantity cannot be stored as a number, only calculated from whichever component you have least of.

Full of assorted bandages, gauze, a set of tweezers, alcohol wipes, etc., this single kit is a perfect example of the utility of combining related items together into one package.

Flash forward to today, and product kitting has become an incredibly important part of the eCommerce retail landscape. From DIY projects to subscription boxes, the market has recognized and embraced the benefits of kitting for both consumers and merchants alike. 

At SkuNexus, we design management software systems to help online brands streamline and improve their eCommerce backend operations. From inventory management to order fulfillment to customer satisfaction, we know how useful kitting can be.

Here, we would like to briefly discuss the fundamentals of kitting, take a quick look at the kitting process, and touch on how brands can employ it to bolster efficiency, reduce costs, and increase sales.

What is Kitting?

In a warehouse, kitting is the process of picking several component SKUs and assembling them into a single new sellable unit, the kit, which is then stocked, counted, picked, and shipped under its own SKU.

It can be helpful to understand what something is by also learning what it is not. Because many people often confuse kitting and bundling, let’s begin by explaining the differences between the two.

Bundling and kitting both involve grouping multiple products together and selling them as a whole. The critical difference lies in how they are managed within a merchant’s inventory system. 

When a retailer notices that customers who buy X also like to buy Y and Z, and then offers all three items together for purchase, it has bundled them. They will most likely be packaged and shipped in the same box, however the shopper who orders the bundle is still buying three individual items (each with its own SKU).

When kitted items are sold, the group itself is treated as a single unit and identified in inventory by a unique SKU. Thus, kitting not only simplifies inventory management but also helps optimize the fulfillment process. By assembling pre-packed product sets, for example, a merchant can reduce the amount of time warehouse employees spend picking, packing, and shipping the order.

How to Track Inventory for Bundles With Shared Components

You track inventory for product bundles by defining each bundle as a recipe of real component SKUs: stock is counted only at the component level, every bundle sale deducts its components, and bundle availability is calculated as the smallest number of complete recipes your component stock can cover. The bundle itself holds no stock of its own. This is how inventory platforms, SkuNexus included, keep bundles honest when the same component appears in more than one bundle or also sells on its own.

Why Do Bundles Oversell Even When Inventory Looks Correct?

Bundles oversell when sales channels are given a static kit quantity instead of a number calculated from live component stock. The kit count looks correct on every channel, but two failure modes quietly break it: a component shared by two bundles gets committed twice, and a sale of a component on its own never lowers the bundle count. Either way, channels keep advertising kits the warehouse can no longer build. The fix is structural, not a bigger buffer: count stock only at the component level, recalculate each bundle's availability as the smallest number of complete kits your components can cover, and push that number to every channel after every sale. That per-sale recalculation, which SkuNexus performs automatically, is what keeps a bundle's advertised quantity honest.

A worked example. A two-item bundle contains one unit of SKU A and one unit of SKU B, with 40 units of A and 25 units of B on hand. Bundle availability is 25, because B runs out first. Sell one bundle and you have 39 A, 24 B, and 24 bundles available. Sell one B on its own listing and bundle availability drops to 23 even though no bundle sold. If a second bundle also uses B, its availability recalculates at the same moment, because both recipes draw on the same shrinking pool of B.

To set this up:

1. Give every physical item its own component SKU. Only components carry stock counts.
2. Define each bundle or kit as a recipe listing its component SKUs and the quantity of each.
3. Let the system calculate bundle availability as the minimum, across components, of on-hand quantity divided by the quantity the recipe requires.
4. Deduct components on every sale, whether the customer bought the bundle or a component on its own.
5. Sync the calculated availability to every channel, so your store, marketplaces, and wholesale portal all quote the same number.

A useful threshold: if every component belongs to exactly one bundle and you sell on a single channel, a spreadsheet can keep up for a while. The moment a component is shared across bundles, sells on its own listing, or sells on a second channel, availability has to be recalculated on every order, and that is work only a system that stores bundles as recipes can do reliably.

Types of Kits

The range of what can be put together into a kit is virtually limitless, but the types of kits generally fall into a handful of different categories.

Subscription Boxes

The eCommerce-fueled explosion of this model has created countless entrepreneurs eager to develop ideas and funnel concepts into the system. From skin care products to dog treats to slimes-of-the-month, this sector now accounts for more than $20B/year in revenues with some projections to rise another 300% by the end of the decade.

DIY Project Kits

The DIY project kit often contains a seemingly disparate group of tools, materials, ingredients, etc., to make a particular final product. From arts and crafts to knife making to coffee roasting, the kit will contain everything needed for an at-home hobbyist.

Consumable Gift Kits

Traditional gift sets of wine and cheese have given way to artisanal and exotic combinations to please any palate. Coffees, teas, spices, and sauces are now available in kits from every corner of the world.

Product Kits

Product kits typically include different versions of the same product or a number of related products frequently bought together. As a means of inventory management, they can also be used to enhance the sales of products that aren't doing well by mixing them with those that are. 

Where kitting actually gets hard

On paper the process is simple: pick two or more items, give the group a new SKU. Across recorded conversations with mid-market merchants, that is not the part anyone struggles with. One operator running a build-heavy catalog put it plainly: getting the software right "has always been a challenge because of the way we do kitting." The difficulty is always the same, and a spreadsheet or a lightweight tool cannot do it.

How Do You Forecast Demand for Shared Components?

You forecast demand for shared components by translating bundle-level forecasts into component-level demand: multiply each bundle's forecast by the quantity of the component in its recipe, add expected sales of the component on its own, and buy against that combined number and the component's own lead time. Forecasting each bundle separately misses the interaction: two bundles drawing on one component can both look healthy while the shared component is the true constraint. That is why reorder points belong on components, not on kits. It is the same reason component-level tracking matters day to day: the component, not the bundle, is the unit that actually runs out.

A kit's availability is a calculation, not a stored number. If a gift set contains three components and you hold twelve of the first, three of the second, and forty of the third, you can sell three sets. Not because of anything about the set, but because the scarcest component caps it. The moment any component sells on its own, that ceiling moves. A furniture merchant we spoke with described exactly this shape: a single sofa listed as one product is three separate SKUs underneath, and selling any of those parts has to deduct from the finished item automatically or the count drifts within a day.

The parent and its children have to move together. When the kit sells, every component SKU must deduct. When a component sells alone, the number of available kits must drop. Systems that treat the kit as its own independent stock line, disconnected from its parts, oversell one side or the other. The merchant above framed it as a parent SKU with child SKUs assigned to it, where an order against the parent deducts each child in the background. That relationship is the whole job.

Partial and made-to-order kits break simple models entirely. Not every kit is pre-assembled and sitting on a shelf. One architectural hardware operation pairs components together per customer order rather than in advance, with a quality-control step reading the build list as it comes down the pick path. Another described selling in kits that break back out into individual SKUs on the way to fulfillment. If your tool assumes a kit is either fully built or not built at all, neither of these operations fits it.

The Kitting Process

At its core the kitting process involves selecting two or more items and assigning them a new SKU. As the section above shows, the operational reality is where it gets demanding. A few best practices matter.

Pre-Kitting vs On-Demand Kitting: Which Should You Use?

Pre-kitting builds kits ahead of demand and stocks the finished kit as its own unit; on-demand kitting stores only components and assembles each kit when an order arrives. Pre-kitting makes picking faster but locks components into a single use: a unit sealed inside a gift set cannot ship to the customer who ordered it alone. On-demand kitting keeps components available to every bundle and listing that uses them, and lets bundle availability float with component stock, at the cost of a build step at pack time. On-demand is the right default when components are shared across bundles or also sold individually. Pre-kitting earns its place for high-velocity kits with dedicated components, such as a subscription box packed in bulk before a monthly ship date. SkuNexus supports the on-demand model natively by decomposing each kit order into component picks at order time.

Fixed Bundles vs Dynamic Bundles

A fixed bundle has a set recipe, the same components every time, sold under one kit SKU; a dynamic bundle lets the buyer choose components at purchase, like a build-your-own gift box. The inventory difference is bigger than the marketing difference. A fixed bundle's availability can be published to every channel ahead of time because its recipe is known. A dynamic bundle's availability can only be enforced per component at checkout, and the order must carry the chosen components as line-level detail so the warehouse picks exactly what the buyer selected. If your platform supports only fixed recipes, dynamic bundles end up faked with manual order edits, and that is where mis-picks start.

First, a merchant must determine what products will comprise the kit, and multiple strategies can be employed here. As mentioned above, the bundle of complementary items often purchased together is a logical option, as is using sales data to group underperforming SKUs with best sellers into a single package. Providing visibility for new items by combining them with long-standing ones is another possibility.

If a brand is handling its own fulfillment, decisions will need to be made for packing the kits. At a bare minimum, the products should be stored in the same area of the warehouse. Protocols must be established to ensure accuracy in inventory deduction, assembling the kits and use of packing materials just as they would be for normal order fulfillment.

Above all, the system of record has to keep the kit and its components in lockstep, deducting the right stock whether the kit sells or a component sells on its own. That is the single requirement a spreadsheet cannot meet.

When kitting is not the answer

If the items customers buy together genuinely are separate products that just ship in one box, that is bundling, and forcing a kit SKU onto it adds inventory complexity you do not need. Keep the SKUs separate and group them at checkout. Kitting earns its overhead only when the group is sold, counted, and reordered as one thing, or when assembly happens in the warehouse and the finished unit needs its own real availability number. If neither is true, a bundle is the lighter and more honest model.

Kitting vs Assembly: What Is the Difference?

Kitting groups existing sellable items into a new SKU without changing them; assembly transforms parts into a finished product that did not previously exist as a sellable item. The practical test is reversibility. A kit can be broken back down and every component returns to stock at full value; an assembled product cannot be un-built. That is why kits are tracked as recipes over component inventory, while assembly consumes inputs and creates a new inventory record. Plenty of merchant warehouses run both without being manufacturers: engraving, monogramming, or a final build step on top of a standard kit. SkuNexus handles that case with custom assembly steps at fulfillment alongside kit decomposition, so a build step can ride on a kit without treating the warehouse like a factory.

Benefits of Kitting

Kitting provides significant convenience and value for customers while at the same time helping merchants increase sales, reduce costs and manage inventory.

How Does Kitting Affect Order Management?

Kitting changes what an order means to the warehouse: the customer buys one kit SKU, but the floor must pick several component SKUs, so the order management system has to translate between the two at order time. When a kit order arrives, the OMS decomposes it into component picks, commits those components, and keeps the customer-facing order as a single line so tracking and customer communication stay simple. Returns run the same translation in reverse: the kit comes back as components, each inspected and restocked at component level. In SkuNexus this decomposition happens automatically when the order is captured, which is what lets a merchant sell kits on every channel without maintaining separate warehouse instructions for each one.

Grouping related items together saves shoppers time, first and foremost. From a gift-buying perspective, the convenience provided by kitting assortments at various price levels simplifies what can be an arduous process. Merchants can also pass the savings along to customers. The price difference of a kitted group vs. buying the same items a la carte is an excellent selling point.

For online retailers, kitting underperforming items with best sellers can be an effective way of managing excess inventory, and in fulfillment terms, pre-packing kits means the order goes straight from picking to shipping. Errors can be virtually eliminated, delivery times speeded up, and materials/shipping costs are lowered thanks to the simplicity of the methods involved.

We have only scratched the surface of kitting here. It provides a range of opportunities for both startup retailers and established brands alike, and we will go into greater depth in future articles.

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