printed letterbox boxes

Printed letterbox boxes are slim postal boxes, printed with your branding, that are sized to pass through a standard letterbox and travel at Royal Mail large letter rates. Custom Postal Boxes makes printed letterbox boxes in the UK in kraft and white board, with print on the outside and inside, low minimum order quantities and free UK delivery. The customer gets a parcel that arrives even when nobody is home, and it carries your brand from the mat to the table.

Why printed letterbox boxes work so well

A parcel that fits through the letterbox removes the weakest link in online delivery: the moment the courier finds nobody in. There is no card through the door, no depot trip and no second attempt, so orders complete first time far more often. Print adds the second benefit. A letterbox parcel is picked up from the mat and carried into the home, and a branded box makes that first physical contact with your shop feel deliberate rather than anonymous.

The format suits any flat product or flat packed set: beauty refills, socks and accessories, books and stationery, pet treats, seeds, craft kits and subscription samples. Our unprinted and printed options start from the same proven shapes as our letterbox postal boxes and large letter postal boxes, so the structure is already matched to the postal bands described below.

The size limits that define the format

A Royal Mail large letter can measure at most 353 mm by 250 mm by 25 mm and weigh up to 750 g, packed and sealed. Every part of the packed parcel counts, including the board, the product and any leaflet or fill, so the working thickness of the box should sit a little under 25 mm to leave headroom. The Royal Mail size and weight guide confirms the current limits, and it is worth checking before a large print run locks in a size.

What fits inside a letterbox box

Anything flat, or anything that can be arranged flat. Products up to around 20 mm thick pack comfortably, and slim items can be layered with a leaflet or a card between them. If the product is thicker than the format allows, it belongs in a small parcel box instead, because a bulging letterbox parcel can be reclassified and charged at parcel rates.

Print choices for a small, slim box

A letterbox box has less print area than a standard mailer, so the design has to work harder. A bold logo and one strong brand colour on the top panel carry further than detailed artwork at this scale. Print inside the lid is where the format shines: the box opens flat, the whole inside is visible at once, and a message, a set of instructions or an offer sits exactly where the customer is looking. White board gives the brightest colour results, while kraft board gives a natural look that suits refill and eco led brands.

Because these boxes are ordered by subscription services, refill brands and gift sellers who send to home addresses, consistency matters. The same size and print on every send builds recognition month after month. Low minimum quantities let you start with a single design, test it with real customers and refine it before committing to a longer run.

Ordering printed letterbox boxes

Share the size of your product as packed, the weight of the finished parcel and the artwork you have, even if it is only a logo. Free design support will set the print up for the slim panels correctly. Pricing depends on size, material and quantity, and delivery across the UK is free, so request a quote through our contact page and ask for the internal size to be confirmed against the large letter limits before printing.

FAQs about printed letterbox boxes

What is the largest size for a printed letterbox box?

The packed parcel must stay within the Royal Mail large letter limit of 353 mm by 250 mm by 25 mm and 750 g. Most letterbox boxes are made a little under the thickness limit so the sealed parcel, including its contents, stays safely inside the band.

What products suit letterbox packaging?

Flat products and products that can be arranged flat work best: beauty refills, books, stationery, socks, accessories, pet treats, seeds and sample kits are all common. Anything thicker than about 20 mm as packed is usually better in a small parcel box.

Can I print inside the box as well as outside?

Yes. Inside print is one of the strengths of this format, because the box opens flat and the whole inner lid is visible at once. It is a natural place for a welcome message, product instructions or an offer for the next order.

What happens if my parcel goes over the large letter thickness?

A parcel that exceeds 25 mm in thickness or 750 g in weight is charged as a small parcel instead. That is why the box should be sized with headroom and the finished parcel weighed before you commit to a postage service.