Custom Flat Cardboard Boxes for Shallow, Wide Items

What are flat cardboard boxes?

A flat box is simply a shallow one. Its height is small compared with its length and width, so it lies flat like a tray. The photos show the classic open-flap slotted version and a shallow mailer tray. There is also a slim wrap style next to a stack of flat-packed blanks.

The term can confuse people, because every box we make arrives flat packed. On this page, flat means the shape of the finished box: low, wide and thin. That shape is ideal for items that should not be folded, stacked loosely or stood on end. A low box also feels tidy in the hand, which matters for clothing and gift orders.

Why choose a flat box over a deeper one?

A box that matches the item's real height protects it better. A thin print in a deep carton can slide, lift and crease. In a shallow box sized to it, the item stays put with little or no filler.

Shallow boxes also save money further down the line. They take less board, use less void fill and often fall into a smaller parcel size. Our guide to cutting UK postage costs shows how box size affects the price you pay.

They stack neatly on shelves and in vans too. A pile of flat boxes stays stable, while a pile of deep boxes with thin items inside wastes space and can tip.

Which flat box style should I choose?

There are three main shapes for shallow boxes, and they suit different jobs. Pick based on how the item goes in and how much protection it needs on the way.

Which board stops a flat box from bending?

Wide, shallow boxes have big panels with little support from the walls. That makes the top and base more likely to bow. The right board keeps them straight. Shallow side walls also give less strength than tall ones, so the board itself has to work harder.

E flute at about 1.5 mm is fine for smaller flat boxes holding clothing or paper. B flute at about 3 mm suits most medium flat boxes. For large frames, mirrors or canvas, BC double wall at about 7 mm keeps the panels rigid. Our single and double wall comparison explains the difference in more detail.

Can I print on a flat box?

Yes, and the wide top panel gives you plenty of space. A large logo or pattern on the top reads well when the box lies on a doorstep or counter. You can also print inside the lid of a mailer tray, so the customer sees a message on opening.

Choose one colour, two colour or full colour CMYK print. Finishes such as matte or gloss lamination, foil stamping and spot UV are available on printed styles. Plain kraft also works well for trade and paperwork orders. If the box will carry a courier label, leave a clear area on the top panel so the label does not cover your logo.

What goes wrong with flat box orders?

The most common issue is measuring the height without the packaging. Even 5 mm of bubble wrap can stop a lid from closing. Take the height measurement with all wrapping in place.

Another is using thin board for a wide box. A large E flute panel can bend in the post. Choose B flute or double wall for anything over about 500 mm long. A third mistake is ordering a deep box for a thin item, which wastes space and leaves the item free to slide. Our edge protectors for frames and panels help when items have fragile corners.

How are flat boxes delivered?

Shallow boxes pack very tightly when flat, so even large orders arrive in compact bundles. We send them on a tracked service, arriving in 2 to 3 business days. Shipping costs you nothing anywhere in the UK.

Open a bundle and build one box with your real item before packing the rest. If you find misprints, transit damage or other defects, send photos within 10 days. We reprint the flat boxes or refund your order. Store the bundles lying down, never leaning against a wall, so the wide panels stay straight until you fold them.