Kitting and Assembly Services for Ecommerce Brands

TL;DR

Kitting combines separate products into one sellable unit, such as a gift set, bundle or subscription box, and a 3PL can take that work off your kitchen table at scale. This guide explains how kitting differs from contract packing, how pre-kitting and kit-on-demand work inside a warehouse, and what shapes the per-unit price, with a worked example. It also covers when in-house kitting or a contract manufacturer suits you better.

Key Takeaways

Kitting looks simple from the outside, and the points below summarise what actually decides whether outsourcing it works.

• Kitting assembles finished products into a kit, contract packing covers packing a brand's goods to its specification more broadly, and contract manufacturing makes the product itself
• Pre-kitting speeds up despatch but ties stock into a fixed configuration, while kit-on-demand keeps components flexible at the cost of slower picking
• The parent-child SKU structure, where one kit SKU draws down several component SKUs, is where most kitting errors start
• Per-unit kitting prices depend on labour time, component count, consumables and setup, so a quote only makes sense against your own kit design
• For simple two-item bundles at low volume, in-house kitting is often cheaper, and regulated assembly belongs with a specialist rather than a 3PL

The worked example in the cost section shows the arithmetic, so you can test any quote against your own numbers.

Kitting and Assembly for Ecommerce Brands

It is 11pm, the product launch goes live tomorrow, and you are still at the kitchen table building gift sets from three boxes of components. Many growing brands reach that point, usually just after a bundle or gift set starts selling better than expected. Kitting moves that work into a warehouse, where trained staff assemble kits to a written specification, either in batches ahead of demand or as orders arrive. This guide is for ecommerce brands selling bundles, gift sets, subscription boxes or retail-ready packs who want to know how outsourced kitting works and what it costs.

You will learn what kitting means, how it differs from contract packing and assembly, when brands need it, how a warehouse runs it, and how pricing works, with a worked example that shows the arithmetic. The guide also explains where a 3PL's scope ends and a contract manufacturer's begins, a boundary that providers sometimes blur. The FAQ at the end answers the questions brands ask most often, including how pre-kitting and kit-on-demand compare.

A word on where we stand before going further. Gonini is a UK and EU fulfillment provider that sells kitting, so we have a commercial interest in brands outsourcing it. The limitations section tells part of this audience to keep kitting in-house, and it names the kinds of work a 3PL should not take on at all. Those points stay in because a kitting guide that hid them would cost some readers money.

Pricing figures in this guide come from an illustrative example with every assumption stated. There is no common pricing standard in UK fulfillment, and each 3PL structures and names its fees in its own way. Treat any figure here as a reference point for checking quotes rather than a price you should expect.

Quick Summary: Service Types Compared

Kitting sits within a family of related services, and providers use the names loosely. The table compares five common services by what each involves, where brands use it, how providers price it and the usual lead time. Lead times here are indicative and depend on volume, complexity and the provider's capacity.

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Most ecommerce brands start with kitting and occasionally need rework, while contract packing more often serves food, drink and retail brands working at higher volumes. Assembly sits at the edge of what a 3PL should offer, and a later section explains that boundary. Subscription box builds combine kitting with a fixed calendar, which brings its own planning demands.

How We Compared the Services

We compared the five services on what each involves, where brands use it, how providers price it, and how long it usually takes. We based the descriptions on common UK fulfillment practice, published industry definitions and Gonini's own kitting operation, which the pre-kitting section describes. Where a definition comes from an industry body, we name it. For pricing, we built a cost model from labour time, consumables and setup: the labour time per kit multiplied by a loaded hourly wage, plus consumables and a setup fee spread across the batch. Our worked example follows that structure and uses illustrative figures with every assumption stated, so you can swap in your own.

We also considered the trade-offs brands report most often: cost per unit, lead time, stock tied up in kits, and errors in kit contents. Those four factors shape every section that follows.

What Kitting Actually Means

Kitting means combining two or more separate products into a single unit that sells under its own SKU. A gift set, a starter bundle and a subscription box are all kits. The terms around kitting overlap, so the two sections below set out clear definitions.

Kitting, Bundling and Assembly Defined

Kitting is the physical work of putting components together into a finished kit, usually in a box, bag or sleeve, ready to sell. Bundling often describes the same idea from a listing point of view: a bundle is a product offer containing several items, which may or may not be physically kitted in advance. Assembly goes a step further and involves joining parts together, such as fitting an accessory to a product or building a display unit.

Providers often group kitting into tiers by complexity: simple kitting covers two or three components with no rework, complex kitting covers four to ten components following instructions, and light assembly involves tools, torque settings and safety checks. That tiering helps when you compare quotes, since a provider pricing simple kits cannot reasonably charge the same rate for complex ones.

How Kitting Differs from Contract Packing

Contract packing means outsourcing packing work to a specialist that packs a brand's products to the brand's own specification. PMMI, the US packaging trade association, defines it as handing the packaging function to a specialist contract packer, or co-packer, which packs products for the brand owner at its own facility, using the brand's specifications, materials and quality standards. Kitting is one of the tasks a contract packer may perform, alongside shrink wrapping, labelling and building promotional packs.

Contract manufacturing is different again. Under the same framework, a contract manufacturer sources and owns the raw materials, makes the product itself and then packs it, whereas a contract packer works with finished goods the brand supplies. In the UK, the BCMPA represents both groups; it formed in 2000 and its members span food and drink, nutraceuticals, chemicals, personal care, pharmaceuticals and household products.

For an ecommerce brand, the practical difference is scope and scale. A contract packer often works on large production runs for retail and wholesale, sometimes with specialist equipment and food or cosmetics accreditations. A 3PL that offers kitting works on smaller, more frequent batches tied directly to ecommerce orders, with the kits stored and shipped from the same building.

When Brands Need Kitting

Brands usually turn to outsourced kitting when one of three product types starts to grow: bundles and gift sets, subscription boxes, or retail-ready packs. Each puts different demands on the warehouse. The sections below cover each one.

Multi-Item Bundles and Gift Sets

Bundles and gift sets are the most common reason brands start kitting. A skincare brand might sell a cleanser, toner and moisturiser as a set, or a coffee brand might pair beans with a grinder. Demand for these kits often spikes around Christmas, Mother's Day and Black Friday, which is exactly when building them in-house becomes unmanageable.

The planning challenge is timing. Pre-building gift sets before peak lets the warehouse ship faster when orders arrive, and yet unsold sets after peak leave components locked in a configuration that may not sell in January. Many brands pre-build a cautious quantity, then switch to kit-on-demand once early sales show how demand is tracking.

Subscription Boxes

Subscription boxes combine kitting with a fixed despatch calendar. Each cycle brings a new mix of components, a build window before the send date, and a large batch of identical or near-identical boxes leaving at once. Our guide to subscription box fulfillment covers the full operation.

The contents often change every cycle, which means new component SKUs, new kit specifications and new setup work each time. Providers handle that change with very different levels of skill, and subscription box providers compared sets out what to look for. Ask how a provider manages late component deliveries, since a single late item can hold up the whole build.

Brands still planning a subscription offer should think about kitting before launch rather than after. The number of components, the box size and the level of personalisation all affect cost per box, and our guide to starting a subscription box covers those early decisions.

Retail-Ready and Marketplace Prep

Retail and marketplace channels often need stock packed in particular ways, such as multipacks, labelled cartons or bagged units. Amazon sets its own preparation and labelling rules for stock sent into its network, and our guide to Amazon FBA prep in the UK explains what that work involves.

Retail-ready packs add packaging decisions on top of kitting. Shelf-ready trays, display boxes and branded sleeves all need sourcing, storage and a clear specification. Our overview of ecommerce packaging choices covers the materials side.

Brands selling across several marketplaces often need the same product kitted differently for each one. A bundle on one marketplace may need different labelling or packaging from the same bundle on another, so the warehouse needs a separate kit specification per channel. The wider picture of marketplace fulfillment explains how those channel rules fit together.

How Kitting Works Inside a Warehouse

Inside a warehouse, kitting comes down to three decisions: when to build kits, how to record them in the system, and how to check them. Each decision affects speed, stock levels and error rates. The sections below explain each one.

Pre-Kitting Against Kit-on-Demand

Pre-kitting means building kits in batches before orders arrive and storing the finished kits as stock. Pickers then pick a single kit SKU, which keeps order picking fast and simple. The cost is flexibility, since components sit locked inside kits that may not sell, and breaking kits apart later costs labour.

Kit-on-demand means storing components separately and assembling each kit when an order arrives. Stock stays flexible, so a component can serve several kits or sell on its own, and no stock gets locked into slow sellers. The cost is speed, since each order involves picking several items and assembling them, which can push complex kits past same-day despatch cut-offs.

Many brands use both. They pre-kit their bestsellers to a forecast and run kit-on-demand for slower or seasonal variants. The right balance shifts over time, so review it whenever sales patterns change.

Gonini's work with a pet supplement subscription brand shows how pre-kitting works in practice. Each month, set groups of pets receive set boxes that are mostly the same, so we know in advance exactly how many orders are coming and who they are for. That lets us pre-kit every box ahead of time, then print the shipping labels and apply them to the finished boxes when the orders drop. The approach does two things:

• Every subscription order goes out the same day it comes in
• It costs the brand less than picking each order on demand, and the extra lead time leaves room for more customisation

Predictable demand is what makes this work, which is why subscription brands with fixed cycles often benefit most from pre-kitting.

Component Inventory and the Parent-Child SKU Problem

Every kit creates a parent SKU, the kit itself, made up of child SKUs, the components. When a kit sells, the system needs to reduce the stock of each component by the right amount, and when a pre-kit gets built, it needs to move components out of available stock and into the kit. If those links are wrong, stock levels drift, and the brand oversells kits it cannot build.

Most kitting errors start at this bill of materials. A kit specification that lists the wrong quantity of one component, or a component that changes supplier and gets a new barcode, can throw off every kit built afterwards. Good warehouse stock control checks component counts against kit counts regularly, so drift gets caught early.

The problem grows when the same components feed several channels. A component sold on its own through a website and inside a kit on a marketplace needs one stock pool that both listings read from. Our guide to stock sync across channels covers how that works, and it matters more with kits, since one sale can consume several components at once.

Quality Control and Error Rates

Kits fail in predictable ways: a missing component, the wrong variant, a damaged item or a missing insert. Each error reaches the customer as an incomplete order, which often costs more to fix than a simple mis-pick. Quality checks should match the kit's complexity and value.

Scanning gives the strongest control. When the kitting station scans every component as it goes into the kit, the system can flag a missing or wrong item before the kit closes, and how barcodes identify stock explains the method. Weighing finished kits against a target weight adds a second check for missing items, and photographing a sample from each batch gives you a record of how kits left the building.

Ask a provider how it measures kitting errors and what rate it achieves on kits of similar complexity. A provider without a measured error rate for kitting cannot tell you how well it performs, so treat missing data as a warning sign.

What Kitting Costs

Kitting costs depend on how long each kit takes to build, how many components it has, what materials it uses and how much setup each run needs. Providers price these elements differently, so compare quotes on the total cost per finished kit. The sections below explain the main cost components and then work through an example.

Per-Unit Pricing and What Shapes It

Most providers charge a rate per finished kit, and labour time sets most of that rate. A two-item bundle dropped into a mailer takes seconds, while a ten-item gift box with tissue, ribbon and a card can take minutes. Component count, fiddly materials, inserts and any personalisation all add time and cost.

Comparing rates takes care, because UK providers do not price the same way. Third-party logistics has no standard pricing method, so every 3PL builds, packages and names its fees in its own way. A low per-kit rate can come with separate charges for component picks, materials or setup, so ask for every line that applies.

Kit-on-demand often appears on invoices as extra picks rather than as a kitting fee. A kit with four components can therefore add three extra-item charges to every order, before any assembly time.

Setup Charges, Minimums and Component Storage

Setup covers the work before the first kit gets built: writing the kit specification, creating SKUs, building a sample, approving it and preparing the kitting station. Providers either charge it as a one-off fee per project or spread it across the batch, which makes short runs more expensive per kit. Some providers also set minimum batch sizes, since small runs rarely cover their setup time.

Component storage adds a further cost. Kits need every component in stock before building starts, and components with long lead times or large minimum order quantities can sit in the warehouse for months. Packaging materials such as gift boxes take up a lot of space for their value, and you pay to store them whether or not the kits sell.

Build component storage into any cost comparison, especially for seasonal kits. A gift box ordered in thousands for Christmas may cost more to store from August to November than it costs to buy.

A Worked Example at a Stated Volume

The example below prices a batch of 1,000 three-item gift sets built in advance. Every figure is illustrative, chosen to show the arithmetic rather than to predict any provider's price, so replace each assumption with your own numbers.

• Kit design: three finished products placed in a branded gift box with tissue and a printed card
• Build time: 60 seconds per kit, including folding the box, placing the items and closing it
• Loaded labour cost: £18 per hour, covering wages, employer costs and supervision (assumption)
• Labour per kit: £18 divided by 60 kits per hour gives £0.30
• Consumables per kit: tissue and card at £0.15, with the brand supplying the gift boxes
• Setup: £150 for specification, sample and station preparation, spread across 1,000 kits, gives £0.15
• Provider overhead and margin: 30 per cent on labour and consumables, which adds £0.135
• Total: £0.30 + £0.15 + £0.15 + £0.135 = £0.735 per kit, or about £735 for the batch

That batch cost sits on top of normal storage and order fulfillment, so each finished kit still incurs a pick and pack charge when it ships. Halving the batch to 500 kits doubles the setup share to £0.30 per kit, which shows why short runs cost more. Compare the result with UK fulfillment costs per order, and with the value of your own time spent building the same kits, before deciding.

Assembly and Light Manufacturing: Where a 3PL Stops

A 3PL can handle light assembly, and it should stop well short of manufacturing. Light assembly covers tasks such as attaching a strap, inserting a product into a display unit or building a cardboard stand. Those tasks use simple tools, written instructions and visual checks.

The boundary sits where work changes what a product is or how it performs. Filling, mixing, cooking, wiring, soldering, calibrating and anything that creates a new regulated product belongs with a contract manufacturer or a specialist facility. The wider set of services a 3PL provides centres on storage, handling, packing and despatch, with light assembly at its outer edge.

Regulation draws the line more firmly in some categories. Food that a provider opens or repacks, cosmetics that a provider decants or relabels with changed details, and electrical products that a provider modifies can all carry legal duties that a general fulfillment warehouse is not equipped to meet. If a task might change your product's compliance position, check with your own regulatory adviser before asking any 3PL to do it.

Marketing often oversells this boundary, making assembly sound like a small extension of kitting. Ask any provider offering assembly to describe the exact tasks it performs, the tools it uses and the accreditations it holds. If the answer drifts toward manufacturing, use a contract manufacturer.

When Kitting Through a 3PL Is the Wrong Call

Outsourced kitting adds a cost layer and a lead-time layer, and it does not suit every brand. Each kit carries labour, setup and materials charges on top of normal fulfillment, and each batch needs planning time before stock can ship. For some brands those costs outweigh the time saved.

For simple two-item bundles at low volume, doing it in-house is often cheaper. A founder selling a few dozen bundles a week can pack them alongside other orders in minutes, with no setup fee and no component storage charges at a warehouse. Our guide to fulfillment for smaller brands covers when outsourcing starts to make sense.

Pre-kitting also ties up stock in configurations you may not sell. If a gift set misses its season, the components stay locked inside kits until someone pays to break them down. Kit-on-demand avoids that, and yet it slows despatch, so brands with tight cut-offs and complex kits face a real trade-off.

For anything involving regulated assembly, food contact or electrical work, a 3PL is the wrong provider, Gonini included. Contract manufacturers and specialist co-packers hold the accreditations, equipment and processes that work demands. A fulfillment warehouse that takes it on anyway puts your compliance at risk.

Outsourcing also cannot fix a poor kit design. A kit with too many components, packaging that is hard to close or inserts that tear easily will cost more and fail more often wherever it gets built. Simplifying the design before outsourcing usually saves more than any rate negotiation.

How to Brief a 3PL on Kitting

A clear brief stops most kitting problems before the first batch, and it gives you a basis for comparing quotes. Send the questions below with your kit specifications, and ask for written answers.

1. How will you price our kits: per kit, per component pick, per hour or per project, and which setup charges apply?
2. Can you build a sample kit for our approval before the first batch?
3. Will you pre-kit, kit on demand, or support both for different SKUs?
4. How will your system link kit SKUs to component SKUs, and how often will you reconcile them?
5. Will kitting staff scan every component, and do you weigh or photograph finished kits?
6. What kitting error rate do you achieve on kits of similar complexity, and how do you measure it?
7. How much space will our components and packaging need, and how will you charge for it?
8. What lead time do you need for a new kit, a repeat batch and a peak-season build?

Clear, specific answers suggest a provider with real kitting experience. If a provider cannot explain how it links kit and component SKUs, expect stock problems later. A paid sample batch is the cheapest way to test build quality before you commit your peak-season kits.

FAQ

What is kitting in a warehouse?

Combining separate items into one kit with its own SKU. It sits alongside how pick and pack works in most 3PLs.

What is the difference between pre-kitting and kit-on-demand?

Pre-kitting builds kits in batches before orders arrive, so despatch is faster but stock is locked into fixed kits. Kit-on-demand assembles each kit when an order comes in, which keeps stock flexible but slows picking.

When should you pre-kit instead of kitting on demand?

When demand is predictable, such as subscription boxes or bestselling bundles. For slower or seasonal kits, kit-on-demand avoids locking stock into kits that may not sell.

What is the difference between kitting and contract packing?

Kitting builds kits from finished items. Contract packing is broader and covers packing goods to a brand's own specification.

How much does kitting cost per unit?

It depends on build time, components and setup. See the components of a fulfillment bill to compare quotes.

Which UK 3PLs offer kitting and assembly?

Many do, Gonini included. Use the full selection checklist to compare providers on kitting.