The Economics of Parcel Packaging: Costs, Economies of Scale and Externalities

The economics of parcel packaging centres on three issues: the costs a box adds to each order, the savings firms gain by buying packaging at scale, and the waste costs that fall on society when packaging is thrown away. Carriers charge for the space a parcel takes up as well as its weight, so an oversized box raises the cost of every order. Box choice also affects how often goods arrive damaged. Economics helps explain where these costs come from and how firms can manage them without weakening protection.

Why Packaging Costs Matter More as Online Sales Grow

As more spending moves online, packaging becomes a larger part of how retailers compete. According to the ONS, internet sales made up 27.3% of total UK retail sales in August 2026. Almost every one of those sales needs a box or mailer that a shop sale does not.

Demand for packaging is a derived demand: firms do not buy boxes for their own sake, but because they need to deliver goods. However, when online sales rise, demand for postal packaging rises with them, and any inefficiency in the pack is repeated across thousands of orders.

How Box Size Affects Postage: Dimensional Weight Pricing

Carriers have limited space in vans, sorting centres and aircraft. A large, light parcel can take up as much room as a heavy one, so pricing by weight alone would undercharge for bulky items. Many carriers therefore use dimensional weight, which estimates a parcel’s chargeable weight from its length, width and height, then charges for whichever is higher: the estimate or the actual weight.

In the UK, Royal Mail prices letters, large letters and parcels by size as well as weight. A slim-format item has a lower shipping rate than the same item shipped in a deeper box because it is able to fit through a letterbox. Matching a box with its contents provides businesses with a strong reason to use a customised box instead of one standard size for all items.

Fixed and Variable Costs in Custom Packaging

Packaging involves two kinds of cost. Fixed costs do not change with the number of boxes produced: designing the layout, making cutting tools and setting up printing. Variable costs rise with each unit, covering board, ink, glue and the labour needed to fold and pack.

As fixed costs are incurred when each design is set up, the cost per box decreases as order quantities increase. Companies that introduce more sizes and print versions must pay additional setup costs and hold smaller inventories of each design. Thus, this is one reason why packaging suppliers will typically require minimum order quantities for customers.

Standardising Box Sizes to Gain Economies of Scale

A firm can lower its average costs by limiting the number of formats it uses. Ordering larger quantities of fewer sizes allows it to benefit from economies of scale, particularly the purchasing economies that come from buying in bulk. Standard sizes also make packing quicker and simplify staff training.

The challenge is choosing a range that fits most products closely. Retailers selling jewellery, cosmetics, electronic accessories or spare parts often settle on a few sizes of small parcel boxes for compact items, keeping movement inside the pack low while avoiding the postage penalty of a carton that is too large. The aim is to balance the savings from standardisation against the cost of extra void fill when a box does not fit well.

Damage, Returns and the Expected Cost of Under-Packaging

Cutting packaging to the minimum is not always the cheapest option. A thinner board or a tighter fit lowers material and postage costs but may raise the probability that goods arrive damaged. Economists calculate the expected costs of each option by multiplying the cost of damage that will occur by the likelihood that it will occur. The expected total costs include the return shipping cost for the original order, the cost of shipping a replacement product, additional shipping from the replacement product, and any goodwill lost from customers due to the issues caused by return shipping.

For low-value items, a small risk of damage may be acceptable. For fragile or high-value products, spending more on protection can lower total costs. For many businesses, the optimal level of packaging protection is reached when the marginal cost of additional protection equals the expected savings from reduced damage. By testing actual product samples, businesses can derive and estimate these probabilities instead of relying on speculation.

Packaging Waste as a Negative Externality

Packaging also creates costs that fall outside the firm. When boxes are thrown away, local authorities and taxpayers bear the cost of collection and disposal. Economists classify this among the negative externalities of production: costs borne by third parties that are not reflected in the price the buyer pays.

UK policy now aims to shift more of that cost back to producers. Under extended producer responsibility for packaging, organisations that import or supply packaging may be responsible for the cost of dealing with packaging waste, and from 2026 household packaging disposal fees are being adjusted according to recyclability.

Supporters argue that this internalises the externality and rewards lighter, more recyclable designs. Critics argue that businesses will pass most of these costs on to consumers through higher prices. They also point out that the reporting requirements create additional administrative costs for affected businesses. With the current popularity of boxes and materials being used to package goods, it can still be argued that the size of the box being used will impact a business's total shipping costs, as well as the amount businesses are charged by the shipping companies for postage or freight charges.