Cardboard Boxes

Step up to double wall if any of these apply

Rule of thumb: it's the consequence of damage that decides, not the weight. A 4kg box of mugs needs double wall. A 12kg box of paperbacks doesn't.

Source: Royal Mail size and weight guide. Our sizes are internal dimensions, so check the external size of any box close to a limit before choosing the band. Long Postal 635mm is over the Medium Parcel limit, so send it by courier. The weight limit includes the contents.

The box you pick decides two costs, not one: what you pay for the packaging, and what the courier charges you to move it. Get the size wrong and the second one quietly costs more than the first, on every order, forever.

This range covers corrugated cardboard boxes for packing and protecting — single wall and double wall in standard sizes, plus purpose-shaped boxes for mugs, bouquets and long items. Everything is sold by the pack for UK trade and online sellers, with a £75 minimum order.

If your priority is hitting a cheaper Royal Mail band rather than protecting a heavy item, start with postal boxes and mailers instead — those are sized to the bands. This page is about protection and fit.

Single wall or double wall: the only decision that really matters

Corrugated board is fluting sandwiched between liners. Single wall — also written single-walled — is one fluted layer between two liners. Double wall, or double-walled, adds a second flute and a third liner. That extra layer is what resists crushing when something heavy sits on top of your parcel in a cage.

Weight is the obvious test, but it isn't the deciding one. Fragility and stacking pressure matter more. A 4kg box of glassware needs double wall. A 12kg box of paperbacks doesn't. If you've had damage claims on a product line, that line wants double wall regardless of what it weighs.

The other case for double wall is storage. If boxes will be stacked more than three high in a stockroom, or held for months, the extra edge crush resistance is what stops the bottom row deforming.

How thick is the board?

Single wall corrugated is typically around 3–4mm thick; double wall roughly 6–7mm. But thickness on its own tells you very little, because two boards of the same depth can differ enormously in strength depending on the flute profile and the weight of the liners either side of it.

What actually decides whether a box holds is the board grade — the flute type paired with the liner weights. A B-flute board is thinner but takes print better; a C-flute is deeper and cushions more. If you're comparing quotes between suppliers, compare grades rather than millimetres, because millimetres are the number that hides the difference.

If you're not sure what grade you're currently buying, send us a sample or the spec you were quoted and we'll tell you what it is.

Sizing: the cost most sellers never see

UK couriers charge on the greater of actual weight or volumetric weight — length × width × height in centimeters, divided by a figure the carrier sets. Most use 5,000, but it varies, so check the divisor in your own contract.

Worked through: a 356 × 356 × 356mm double wall box has a volumetric weight of about 9kg even if the contents weigh two. You are paying to ship air.

Three habits fix most of it:

Measure your product, then add 20–30mm per side, not 100mm. Void fill is there to stop movement, not to fill a box you shouldn't have bought.

Count how many sizes you actually need. Most operations dispatch 80% of orders from two or three formats. Carrying six sizes ties up capital in slow lines and slows the picking bench.

Check the next size down before reordering. If you consistently use more than a handful of void fill per parcel, the smaller box is cheaper twice — less board, less volumetric weight.

Purpose-shaped boxes

Some items don't fit a cube efficiently, and forcing them into one costs more than buying the right shape.

The square-section tubes are worth a note. A 635mm poster in a standard box means buying a box far larger than the item in two dimensions. A 110 × 110mm section carries the same poster at a fraction of the volumetric weight.

Three mistakes that cost real money

Buying on unit price alone. A box that's cheaper per unit but one size larger can cost more per parcel in volumetric weight than you saved on board. Compare cost per dispatched order, not cost per box.

Using double wall as a default. It's heavier, so it adds to actual weight, and it costs more per unit. Reserve it for what genuinely needs it — over-specifying across your whole range is a slow, invisible margin leak.

Assuming flat-packed means no storage cost. Everything here ships flat, but a pallet of six sizes still needs a rack. Fewer formats, more of each, is the cheaper operation.

Why the price works

We're part of a manufacturing group, and the corrugated board in these boxes is made in-house rather than bought in and marked up. There's no middleman margin in what you pay — you're buying from the people who make it.

That's also why the lead time behaves. When board is made on your own plant you control when it runs, instead of joining a supplier's queue behind their bigger customers.

Trade packs and pricing

Boxes are supplied in trade pack quantities — 20 or 25 for wall boxes, 40 to 100 for postal formats — with a £75 minimum order. Prices shown exclude VAT, which is added at checkout. Current pack prices are on each product page.

Concentrating volume into fewer lines is what earns the better break price. If you're carrying five sizes and using two of them for most orders, consolidating usually costs less overall even if the unit price on paper looks similar.

Alongside our boxes we now make ventilated cardboard delivery trays for bakeries, greengrocers, florists and caterers — open-top, stackable and available to order on a 14-day lead time.

Not sure which formats cover your mix? Send us your dimensions and typical weights and we'll work it through with you.

Still deciding?

• Trying to hit a cheaper Royal Mail band? Start with postal boxes and mailers — sized to Large Letter and Small Parcel.
• Sending flat items or documents? See envelopes.
• Sending books, records or media? Variable-depth book wraps and record mailers fold to the contents.
• Want something lighter than a box? See padded and paper mailing bags.