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  • Correct size for the Royal Mail’s large letter specification
  • Fits through a letterbox for customer convenience
  • 100% recyclable and biodegradable
  • Sturdier eco-friendly alternative to bubble mailers
  • Available in five sizes that all fit within the large letter limits
  • Do not overfill to stay within large letter restrictions
  • See more product information...


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    What is a large letter postal box?

    These narrow postal boxes comply with the Royal Mail’s large letter size specifications by all having a height, sometimes called ‘thickness’, measurement no larger than 25mm. The maximum weight is 750g and the length and width must be a maximum of 353mm and 250mm respectively. 

    However, there is no need to meticulously measure your parcel when using our specifically designed postal packaging; each product on this page will fit into the large letter category provided that the boxes are not overfilled causing the contents to bulge, enlarging the dimensions of the parcel. 

    It is important to note that overstuffed boxes that cause the cardboard to bend will not be classed as large letters by the Royal Mail and may incur higher postal prices. To fit into the large letter specifications, these box lids must lie flat. 

    Why should I use a large letter sized cardboard box?

    There are several practical benefits to selecting large letter boxes for your ecommerce delivery needs.

    Firstly, your company can accurately calculate postage costs in advance by consistently using this style of packaging, establishing regularity compared to the differing widths that can occur when packaging products in flexible mailing bags. Kite’s selection of large letter boxes offer this cost-saving consistency at highly competitive wholesale prices to minimise your outgoings further.

    The corrugated cardboard boxes also have a durability advantage over mailing bags by being more rigid and hence, providing a greater degree of protection to the contents. If you are packaging particularly small or breakable items, you can surround the product with void fill or cushioning to prevent movement within the box to further safeguard against potential damages.

    The compact boxes are an aesthetic way of packaging products with the hinged lid attractively displaying the contents. This creates an enjoyable unboxing experience for your customers, elevating their impression of your entire brand. Moreover, the slim letterbox design allows the package to be safely delivered even if the recipient is not in, increasing the efficiency and ease of the order. 

    What are large letter boxes used for?

    These lightweight cardboard boxes are excellent methods of economically packaging small ecommerce goods. This includes jewellery, wrapped foodstuffs, cosmetics, handmade gifts and trinkets, to name just a few. 

    The large letter cardboard boxes are very convenient for even fragile items due to their robust construction and the size that allows for very little internal movement, particularly if combined with void fill packaging. This reduced movement equates to a reduced chance of internal impacts that can cause damage to the contents. 

    Are cardboard boxes eco-friendly?

    These cardboard large letter boxes offer a plastic-free, low-cost method of transporting small items through the post. They are fully recyclable and biodegradable, making them an eco-friendly option when compared to bubble mailers, for example, which utilise single-use plastic that may not be widely recycled. The brown cardboard boxes are recognisable eco-friendly, ensuring customer satisfaction and responsible disposal once an order has arrived. 

    What packaging should I buy with a postal box?

    By being popular with small gift and ecommerce markets, our large letter postal products are frequently paired with gift packaging. This can include wrapping the item with tissue paper and surrounding it with shredded void fill before completing the package with a strip of custom tape. 

    For an efficient dispatch system, many retailers will partner their letterbox boxes with printed labels that have customer delivery information clearly visible. Kite supply a range that are compatible with laser printers, inkjet printers and copiers in addition to labels on a roll that are ideal for smaller businesses.