printed large letter boxes

printed large letter boxes are slim cardboard boxes, printed with your branding, that stay within Royal Mail large letter limits so flat products post at the large letter rate and fit through most letterboxes. Well made printed large letter boxes protect contents with rigid board while keeping the finished parcel no more than 25mm thick and no heavier than 750g.

The size rules printed large letter boxes must meet

Royal Mail large letter limits are a maximum length of 353mm, a maximum width of 250mm, a maximum thickness of 25mm and a maximum weight of 750g, measured on the finished packed parcel. The Royal Mail guide to sending small parcels confirms those limits alongside the small parcel band. Thickness is the measurement sellers most often miss, because board, contents and any padding all count, and a parcel that bulges in the middle can be charged as a small parcel instead.

Designing within 25mm

Work backwards from the limit. Choose board that gives rigidity without bulk, keep internal protection thin and flat, and measure the packed box at its thickest point, including the closure. A wrap or shallow box format usually beats a deep box folded down, because the shape stays flat under sorting pressure.

Weight headroom

Cardboard, product and paperwork must together stay under 750g. Slim board helps twice here, once on thickness and once on weight, and most flat goods such as books, documents, clothing accessories and media leave comfortable headroom when the box is sized closely.

What to post in printed large letter boxes

Typical contents include A4 documents and certificates, magazines and comics, slim paperbacks, phone cases, flat clothing items, craft kits, prints and promotional packs. If the product is flexible, the rigidity of the box protects it from bending in transit, which is the main weakness of a large envelope. Our large letter postal boxes and letterbox postal boxes show the core formats, and printed postal boxes covers branded postal packaging in larger bands.

Letterbox delivery changes the customer experience. Parcels that fit through the box arrive without a missed delivery card, returns trips or a wait at a collection point, which reduces queries for the seller as well. Print that includes your name on the top panel helps the customer recognise the sender before opening, and a short message inside the lid works well for care notes or reorder details.

Print choices for slim boxes

Slim boxes have generous flat panels, ideal for a bold logo, a colour block or a clear product message. Single colour print on kraft looks smart and economical, while full colour on white board carries photography and bright branding. Keep the delivery label area in mind when laying out the top panel, and place the most important artwork where a label will never cover it.

Order printed boxes sized to your product

Custom Postal Boxes manufactures printed boxes in Wolverhampton with low minimum order quantities, free design support and free UK delivery. Pricing depends on size, material and quantity, so request a quote with your product dimensions and packed weight, and see our guide to small postage boxes UK sellers use when an order grows beyond large letter limits.

FAQs about printed large letter boxes

What are the Royal Mail large letter size limits?

The finished parcel must be no longer than 353mm, no wider than 250mm, no thicker than 25mm and no heavier than 750g. Measure the packed box at its thickest point, because board and padding count towards the thickness.

What products suit large letter boxes?

Flat and slim products suit them best, including documents, magazines, comics, slim books, prints, phone cases, flat clothing accessories and craft kits. Anything that keeps the packed parcel within 25mm thick and 750g can travel at the large letter rate.

Can large letter boxes be printed inside as well?

Yes. Inside print suits a thank you message, care guidance or reorder details and is revealed when the box opens. Outside print carries the branding and sender recognition, with space planned around the postage label.

What happens if my parcel is slightly too thick?

A parcel over 25mm thick or over 750g is charged as a small parcel, which costs more. Sizing the box closely, using slim board and measuring a packed sample before you buy postage keeps you safely in the large letter band.