Kitting at a 3PL means building several components into one sellable unit before anyone orders it: the kit gets its own SKU and barcode, goes on the shelf as its own stock, and ships as one pick. Bundling at pick means the store sells the set as one offer, the order reaches the warehouse as its component SKUs, and the picker builds the set in the box. Which one you want depends on how fast the set sells, whether the customer chooses variants, what the packaging has to look like, and what it would cost to take unsold kits apart.
What kitting is, and how bundling at pick is different
Say you sell a cleanser, a toner and a moisturizer, and you want to sell the three together as a starter set. The first way to get that set into a box is to kit it: someone in the warehouse takes one of each out of their bins, puts them in the set's box with the tissue and the card, seals it, sticks the set's own barcode on the outside and shelves it as a new SKU. A SKU, short for stock keeping unit, is the code your store and our WMS (the warehouse management system) use to tell products apart. From then on the set is one product with one count, and an order for it means one pick and one scan.
The second way is to pick to kit. The set is listed in the store as a bundle, and when a customer buys it, the order shows the cleanser, the toner and the moisturizer as three separate lines. The picker pulls each one from its own bin and scans it against the order, and the packer puts the three in the set's box with the card. Nothing was built ahead of time, and the warehouse only ever counted three products. People use 'kit' and 'bundle' for both, which is why quotes get confusing, and the difference that matters is when the labor happens and where the inventory sits.
When pre-kitting wins, and when picking to kit wins
Pre-kit when the set sells fast with a fixed composition and has to arrive looking a certain way: a sealed presentation box, a shrink-wrapped multipack, a set a retailer receives as one unit with one barcode. Pick to kit when the customer chooses a size or a shade inside the set, when the set changes with every promotion, when it sells a few a day, or when the same products also sell on their own and you don't want them locked inside kits.
The hidden cost of pre-kitting is the kits that don't sell: taking one apart is labor again, the box and the tissue are usually a loss, and the components go back to their bins with a count correction. So before you pre-build a season, decide what happens to the leftovers.
| What you're weighing | Pre-kit, built before the order | Pick to kit, built in the box at pack time |
|---|---|---|
| Speed: how fast an order ships | One pick and one scan per set, so a sale that drops thousands of orders costs the pick station one touch per set. | Every component is a pick and a scan, so a three-product set takes three of each. Plan the labor for peak. |
| Inventory: what you count and where it sits | Two counts: finished kits on the shelf and loose components in bins. A build moves stock from one count to the other, and that move has to reach your store the same day. | One count, the components. The bundle's availability is whatever component runs lowest, so a product that also sells alone can drain it without a bundle being sold. |
| Cost: where the labor is billed | Assembly is a batch of hours before any order exists. At YNK that's special-project labor at an estimated $35 per hour, only when you ask for it, plus the kit packaging billed as used. | Nothing is built before the order. At YNK the set ships under one handling fee per order, an estimated $3.00, however many units are in the box. |
| Flexibility: how easily the set can change | Changing a component means a new kit SKU and barcode, and the old kits get sold down or taken apart first. | Change the bundle in the store and the next order picks the new components. The customer can choose a size or a shade inside the set. |
| Best for: choose it when | The set sells fast with a fixed composition, needs a sealed box, shrink-wrap or its own retail barcode, or goes to a retailer as one unit. | The set sells steadily, changes often, offers a variant choice, or uses products that also sell on their own. |
How a Shopify bundle reaches the warehouse
On Shopify, a bundle is 'a set of two or more related products, commonly offered at a discount', and you need a bundles app installed to create one, as of October 2026. Shopify says bundles in orders 'display as a nested group of line items', and with split fulfillments the included items show as individual line items, checked October 2026. With Shopify's own Bundles app, SKUs 'are listed for individual items in orders' and the weight 'is derived from individual item weights', as of October 2026. So the warehouse sees the components, each with its own SKU and weight. A Shopify bundle is pick to kit by design.
Inventory is counted the same way. Bundle inventory 'is determined by the inventory levels of each product included within a bundle', the product with the lowest level 'determines how many bundles can be sold', and a product that isn't tracked drops out of the calculation, as of October 2026. The same page says bundles can't contain other bundles and aren't compatible with purchase options such as subscriptions and pre-orders. In Shopify's app, a fixed bundle holds up to 30 components, checked October 2026.
A pre-built kit takes the other road: an ordinary product with its own SKU, its own barcode and its own tracked quantity, and no bundles app. Shopify says each product and variant 'must have its own unique SKU', with a separate field for the barcode, and once you turn on 'Track quantity', 'when a product reaches zero inventory, customers can't add it to their cart', as of October 2026. The order reaches the warehouse as one line and the picker scans the kit's barcode.
The WMS we run on is ShipStation, and its help center says a product bundle is 'a collection of individual products sold together under a single SKU', its in-stock count shows 'the lowest In Stock count' of its components, and bundles 'will always display the component products on Pick Lists', as of October 2026. The rest of the plumbing, locations, order routing, tracking and refunds, is in how a 3PL connects to Shopify.
Kit inventory versus component inventory, and how to avoid overselling either
With pre-built kits you have two counts, and the build is a transfer between them. Say your store shows 400 moisturizers for sale. If we build 100 starter sets on a Tuesday, the moisturizer count is 300 and the kit count is 100. Both numbers have to reach the store that day, because single-unit orders were draining that shelf at the same time. So book the build like an inbound, with a date and a quantity, and put the kit SKU on sale only after its count has synced. Leave 'Continue selling when out of stock' switched off on the kit, because it lets customers keep buying after the count hits zero, as of October 2026.
With pick to kit there's one count, but the bundle's availability is derived from it. The set can sell only as many times as its scarcest component allows. Say toner also sells alone: every single-bottle toner order lowers how many sets the store can sell, with no set sold. So watch the limiting component, set the reorder trigger on the components and never on the bundle, and track every component in the store, because an untracked product drops out of Shopify's bundle calculation and the set will look available after that product is gone.
Gift sets and seasonal kits: decide by what happens in January
A holiday gift set can go either way. If it has a printed box, a fixed composition and a forecast you believe, build it in a batch before your peak inbound and let it ship as one pick through the peak days. If it's three products in a mailer with a card, pick it to kit, and in January the components go back to ordinary sales without anyone taking a box apart.
The components and the packaging need to be on our shelves before the peak inbound window closes, and the kit needs to exist in the WMS before the first order. The peak season plan puts those dates on a calendar. Then set the January rule now: how many unsold sets you'll keep selling at a markdown, and when the rest get broken down into components.
One more rule for anything with an expiry date. A sealed set carries the earliest expiry of its components and can't be picked first-expired-first-out by component. For supplements, gummies, beverage and food-grade goods we record lot and expiry at receiving and pick the oldest sellable lot first, so a pick-to-kit set keeps that protection and a pre-built kit needs a build date and a sell-by rule of its own.
Inserts, gift notes and personalization, with or without a kit
A lot of what gets called kitting is an insert rule, and an insert rule doesn't need a kit. Tell us the rule and we pack to it: a thank-you card in every box, a sample in every order over a threshold you set, a gift note when the order carries one. We store the cards, samples and boxes you send us and add them at pack, so you can change the rule without touching inventory.
Personalization is where a kit stops being a kit. Keep the personalized piece as its own SKU with its own instruction on the order, and let the rest of the set pick to kit around it.
The kit setup checklist: what to send before the first set ships
Whichever model you choose, send this with your SKU list before the first set ships.
- Components: every SKU in the set with the quantity of each, so a set with two of the same bottle says so, and the lot rule if a component carries one.
- A barcode for the kit, if it's pre-built. GS1's GTIN Management Standard gives a predefined assortment, a fixed set of two or more items sold as one, a GTIN of its own, separate from the GTINs of the items inside, as of October 2026. Put it on the outside, because it's what gets scanned at pick. A pick-to-kit set needs no new barcode, since each component carries its own.
- The packing rule: which box or mailer, what goes in first, which way the labels face, tissue or dunnage, and whether the set is sealed, wrapped, or left open for a card on top.
- Inserts: which card, sample or gift goes in, under what rule, and whether it goes in every set or only when the order qualifies.
- How the store sells it: a plain product with its own SKU and tracked quantity for a pre-built kit, or a bundle in a bundles app for pick to kit, with every component tracked and 'Continue selling when out of stock' off.
- Finished weight and dimensions for a pre-built kit, for the shipping rate and the carton choice, and a photo of a correctly packed set for the packing station.
- The sold-out rule: when one component runs out, does the set go off sale, ship short with a note, or swap in a substitute you've named ahead of time?
- The leftover rule: how many unsold kits you'll keep selling, when the rest get broken down, and what happens to the box.
How kitting is billed and run at YNK
Handling at YNK is one fee per order, an estimated $3.00 with pick, pack and ship included, however many units are in the box. A few order profiles are priced case by case, and your quote will say so. A standing kit is set up once in the WMS with its components and then picks like any other SKU, so a three-product set picked to kit is one order and one handling fee, with three scans before it's sealed. Every unit gets scanned against the order before it goes in the box, which is how pick and pack error stays under 0.3% across more than 1.2 million orders a year, and it's the same process that ships Veiled's orders, which average six pieces, at 99.995% order success.
Building kits ahead of orders is billed differently. Assembly is special-project labor, an estimated $35 per hour, only when you ask for it, and the same rate covers relabeling and breaking leftover kits down. Say we log ten hours building your holiday sets. That's $350 of project labor, and the boxes, tissue and dunnage we used appear on the invoice as supplies, billed as used. Pre-built kits then sit on the shelf as their own cube, and storage is an estimated $0.65 per cubic foot per month on the space you use, so a kit box takes more cube than the same components did in their bins.
The rest of the rate card doesn't move for a kit. Orders in by 12pm ET ship the same business day, later ones within one business day, or two to three in peak, and there are no seasonal or peak surcharges on handling or storage, so a gift set costs the same to handle in December as in June. Postage is billed semi-monthly per shipment. Shopify, Amazon and TikTok Shop orders draw on one inventory pool, so one set of components serves all three. The Shopify fulfillment page covers the connection, and services covers kitting and personalization.
To get a set priced, send us the 3PL intake with your SKU list and the checklist above. It takes about ten minutes, someone from the team replies within one business day, and the proposal follows within five. Components and packaging ship to 465 Mola Blvd, Dock 10, Elmwood Park, NJ 07407.
Questions founders ask about kitting
What is the difference between kitting and bundling?
Kitting builds several components into one sellable unit before it's ordered, with its own SKU, barcode and count. Bundling sells several SKUs as one offer, and the warehouse picks the components when the order comes in. People use both words for both, so ask when the labor happens and where the stock sits.
How much does kitting cost at a 3PL?
At YNK a standing kit ships under the one handling fee per order, an estimated $3.00 however many units are in it. Building kits ahead of orders is special-project labor, an estimated $35 per hour, only when you ask for it, with packaging billed as used. Other 3PLs may charge per kit or per component, so ask which.
Does a bundle need its own barcode?
A pre-built kit does. [GS1's GTIN Management Standard gives a predefined assortment a GTIN of its own, separate from the items inside](https://ref.gs1.org/standards/gtin-management/), as of October 2026. That barcode is what gets scanned at pick. A pick-to-kit bundle doesn't, because each component carries its own barcode and the order lists the components.
Can a 3PL build gift sets for the holidays?
Yes, we do. At YNK a gift set is either built in a batch before your peak inbound as special-project labor, an estimated $35 per hour, or set up as a standing kit and picked to order under the handling fee. Rates don't change in peak, with no seasonal surcharges on handling or storage.
Related: How a 3PL connects to Shopify · Planning peak season with your 3PL · Kitting and personalization, with the rest of the services · Shopify fulfillment at YNK