postal boxes

postal boxes are cardboard boxes sized for sending goods through the UK postal and courier networks, from slim letterbox packs for flat items to sturdy cartons for small parcels. Custom Postal Boxes manufactures postal boxes in Wolverhampton for UK businesses that need the right size, reliable protection and their own print on every parcel they send.

Choosing the correct postal box is a cost decision as much as a protection decision. Royal Mail charges by size band as well as weight, so a box that keeps a parcel inside a lower band saves money on every single order, while board that is too light risks damage, returns and refunds that cost far more than the box.

Types of postal boxes and what each one suits

Letterbox boxes are shallow and wide, designed to pass through a standard letterbox so the recipient does not need to be home. Large letter boxes follow the same idea within the Royal Mail large letter limit. General cardboard postal boxes cover the small parcel sizes most online shops use daily, and heavier shipping cartons in single or double wall board handle weight and stacking on longer journeys.

Browse the range by size in our postal boxes by size category if you already know your band, or look at letterbox postal boxes if avoiding missed deliveries matters most to your customers.

Royal Mail size bands explained simply

Royal Mail large letter allows up to 353mm by 250mm by 25mm and 750g. Small parcel allows up to 450mm by 350mm by 160mm and 2kg. Medium parcel allows up to 610mm by 460mm by 460mm and 20kg. Always measure the finished packed box, including tape and any bulge, and check the current Royal Mail size and weight guidance before fixing a size, because crossing a band boundary by a few millimetres moves the whole parcel into a higher price.

Why packed size matters more than product size

Board thickness, protective wrapping and the way flaps overlap all add millimetres. A product that measures 20mm thick can easily become a 27mm parcel in the wrong pack, which is over the large letter limit. Testing a real packed sample is the only reliable check.

Materials and strength in postal boxes

Most postal boxes are made from corrugated cardboard, where a fluted inner layer gives strength at low weight. Kraft board gives a natural brown finish, white board carries bright print, and recycled content options suit brands with published sustainability aims. Slim letterbox styles often use a finer flute to stay shallow, while parcel cartons use stronger grades that resist crushing when stacked in sacks and vans.

Closure matters as much as board. Peel and seal strips speed up packing and remove tape costs, crash lock bases pop into shape for fast assembly, and standard taped cartons remain the most flexible for varied order sizes. Match the closure to your packing speed and the value of the contents.

Printed postal boxes as a marketing surface

A parcel is the one piece of marketing every customer is guaranteed to hold. printed postal boxes carry your logo outside for recognition on the doorstep and a message, offer or social prompt inside the lid where the unboxing moment happens. Even a single colour print on kraft board lifts a plain delivery into something that looks considered and trustworthy.

How to choose and order postal boxes

Start with your three most common orders. Measure each product packed as you would send it, note the weight, and pick the smallest box that fits without forcing. Order a small range of sizes rather than one compromise size, because most returns for damage and most postage overspend trace back to a box that was nearly right.

Custom Postal Boxes is a project of Vertex Packaging, with low minimum order quantities, free design support and free UK delivery. Ordering is quote based because pricing depends on size, material and quantity. Send your product sizes through our contact page for a quote and we will recommend sizes, board and print in one reply.

FAQs about postal boxes

What size postal box do I need for Royal Mail small parcel post?

A small parcel must stay within 450mm by 350mm by 160mm and 2kg including the box and contents. Choose the smallest postal box that fits your packed product and always measure the finished parcel before buying postage.

Can postal boxes really go through a letterbox?

Yes, letterbox postal boxes are shallow enough to pass through a standard letterbox when packed within the large letter limits of 353mm by 250mm by 25mm. That means the recipient does not need to be at home for delivery.

What is the difference between postal boxes and shipping boxes?

Postal boxes are sized for postal networks and lighter goods, often with letterbox and large letter formats. Shipping boxes are larger cartons, often double wall, built for heavier loads and courier journeys where stacking strength matters more.

Can postal boxes be printed with my branding?

Yes. Postal boxes can be printed outside and inside with your logo, colours and messages, from a single colour on kraft board to full colour designs. Free design support is included and checks artwork against fold lines before production.

Are cardboard postal boxes recyclable?

Yes. Cardboard postal boxes are widely recycled through UK household and business collections once tape and labels are removed where practical. Choosing the smallest suitable box also reduces the amount of material your customers need to recycle.