Letterbox Boxes – 218x160x20mm

Features & Benefits

• Single Wall Cartons 218x160x20mm provide slim packaging for suitable letterbox-sized products
• Nominal size of 218mm x 160mm x 20mm
• Imperial size of approximately 8.6 x 6.3 x 0.8 inches
• Measurements shown as length x width x height
• Shallow 20mm profile suits flat and compact products
• Plain brown cardboard creates a practical kraft appearance
• Single-wall construction provides lightweight everyday protection
• Compact format can help reduce unnecessary parcel space
• Folding panels make each carton straightforward to assemble
• Suitable for posting, storage and product presentation
• Easy to label and incorporate into organised dispatch systems
• Can be combined with tissue, paper, foam or another slim protective material
• Useful for e-commerce, retail, stationery and promotional products
• Customers should measure the finished package before selecting a postal service
• We deliver these cartons to UK mainland addresses

Common Uses

These slim single-wall cartons are suitable for packing:

• Photographs and printed materials
• Greeting cards and invitations
• Gift vouchers and certificates
• Small notebooks and stationery
• Jewellery and fashion accessories
• Mobile phone accessories
• Cables and small adaptors
• Craft products and handmade items
• Small textiles and fabric accessories
• Promotional materials
• Product samples
• Replacement parts
• Slim cosmetic products
• Collectables
• Small retail items
• E-commerce orders
• Boxed or separately wrapped confectionery
• Documents requiring more protection than a standard envelope

However, always check the complete dimensions, weight, shape, value and fragility of the contents. Additionally, use suitable protection whenever an item could move or contact the walls of the carton.

Our letterbox cardboard boxes fit within Royal Mail’s Small Parcel size standard, providing compact packaging for posting flat products, gifts and online orders. Royal Mail allows Small Parcels measuring up to 450mm x 350mm x 160mm (approximately 17.7 x 13.8 x 6.3 inches), with a maximum packed weight of 2kg. Therefore, check the sealed outer dimensions and total weight, including the contents and all packaging, before posting. For further details, visit Royal Mail’s size and weight specifications.

Single Wall Cartons 218x160x20mm

Our Single Wall Cartons 218x160x20mm provide a compact packaging option for shallow products that need more structure than a paper or polythene mailing envelope. Their slim profile makes them particularly useful for printed materials, accessories, samples and other low-height items.

The single-wall cardboard construction combines everyday protection with a relatively low packaging weight. Therefore, the cartons can support efficient e-commerce, retail and postal packing operations.

Moreover, the natural brown finish creates a familiar kraft appearance. Packers can apply address labels, barcodes, handling instructions or branded tape according to the intended application.

The shallow format can reduce unnecessary space around suitably sized products. As a result, businesses may require less internal filling material than they would with a deeper carton.

Because Single Wall Cartons 218x160x20mm have a nominal height of only 20mm, customers should measure the fully packed item carefully. Protective wrapping and cardboard thickness will reduce the available internal space.

Single Wall Cartons 218x160x20mm Dimensions and Specifications

The nominal carton size is:

• Metric: 218mm x 160mm x 20mm
• Imperial: approximately 8.6 x 6.3 x 0.8 inches

The main product specifications are:

• Measurement order: length x width x height
• Product type: shallow letterbox-style cardboard carton
• Construction: single-wall cardboard
• Colour: plain brown
• Finish: natural kraft appearance
• Shape: slim rectangular carton
• Suitable applications: posting, storage, presentation and dispatch
• Nominal height: 20mm, approximately 0.8 inches
• Assembly: folding panels and pre-creased sections
• Closure: secure according to the intended packing and delivery method

The stated Single Wall Cartons 218x160x20mm measurements are nominal. Therefore, small manufacturing tolerances may apply to the completed dimensions.

Furthermore, customers should confirm whether the listed dimensions represent internal or external measurements when an exact fit is essential. The usable internal space will usually be smaller because the cardboard has its own thickness.

Understanding Single Wall Cartons 218x160x20mm Measurements

The measurements follow the order length x width x height. Therefore, each carton measures approximately 218mm long x 160mm wide x 20mm high.

In imperial measurements, this equals approximately 8.6 inches long x 6.3 inches wide x 0.8 inches high. Consequently, the format works best for products that remain consistently slim after adding any necessary protective packaging.

Before ordering, measure every part of the intended item. For example, include raised fittings, clasps, cables, folded fabric and protective wrapping when checking the required space.

Additionally, allow for the thickness of the carton walls. A product measuring exactly 218mm x 160mm x 20mm will not necessarily fit inside a carton with the same nominal external dimensions.

The Single Wall Cartons 218x160x20mm may suit letterbox or large-letter postal services when the completed package remains within the carrier’s current limits. However, customers must measure and weigh the sealed parcel before selecting a service.

Choosing Single Wall Cartons 218x160x20mm

Choose Single Wall Cartons 218x160x20mm when you need shallow packaging for a suitably sized flat product. In particular, consider the item’s complete dimensions, weight, fragility and surface finish.

Single-wall cardboard provides useful rigidity for many everyday postal items. However, delicate, valuable or easily crushed products may require additional cushioning or a stronger outer package.

The product should fit without placing pressure on the side panels or closure. At the same time, excessive empty space can allow movement and reduce the effectiveness of the completed pack.

Therefore, select a carton that provides enough room for slim protection without creating unnecessary space. A close-fitting carton can improve product control and create a neater presentation.

The intended postal service also affects the choice. For example, letterbox and large-letter services normally apply maximum dimensions and weight limits to the finished package rather than the empty carton.

How to Assemble Single Wall Cartons 218x160x20mm

Before assembly, inspect the cardboard for tears, dampness, crushed edges or damaged fold lines. Next, place the carton on a clean, dry and stable surface.

To assemble Single Wall Cartons 218x160x20mm:

1. Identify the base, side panels, closing section and folding tabs.
2. Fold each panel carefully along its existing crease.
3. Bring the side sections into their intended positions.
4. Fold any retaining tabs without tearing the cardboard.
5. Make sure the base remains flat and the corners sit square.
6. Add a slim protective layer where necessary.
7. Position the product centrally inside the carton.
8. Add suitable protection around any remaining movement space.
9. Fold the closing panel into position.
10. Secure the carton according to its design and intended journey.
11. Apply any required address, barcode or handling labels.
12. Measure the completed parcel before selecting a postal service.
13. Inspect the carton before dispatch.

However, do not force the panels or tabs around an oversized item. Excessive pressure can distort the carton and create a package that exceeds the intended 20mm profile.

Finally, check that the completed carton lies flat. Bulging surfaces usually indicate excessive filling or an unsuitable product size.

Packing with Single Wall Cartons 218x160x20mm

The shallow dimensions help control appropriately sized products. Therefore, Single Wall Cartons 218x160x20mm can reduce the need to place flat items inside deeper shipping boxes.

First, identify delicate surfaces, sharp edges and projecting parts. Then, apply a suitable slim protective material before placing the item inside the carton.

Position the product centrally and keep it clear of the outer edges where possible. Afterwards, fill any remaining gaps without increasing the finished package beyond the required postal dimensions.

Suitable protective materials may include:

• Tissue paper
• Kraft paper
• Thin foam
• Corrugated paper
• Small bubble cushioning
• Cardboard pads
• Protective paper sleeves
• Glassine or compatible interleaving
• Slim product inserts
• Suitable document wallets

However, choose the material according to the product. Polished, printed or delicate surfaces may require a soft, non-abrasive layer, while electronic components may require specialist anti-static protection.

Do not overfill the carton or force the closure. Otherwise, pressure may damage the contents, distort the cardboard or increase the finished parcel thickness.

After closing the carton, gently check it for movement. If the contents shift, adjust the internal packaging before completing the dispatch.

Single Wall Cartons 218x160x20mm for Business, Posting and Storage

Our Single Wall Cartons 218x160x20mm support businesses that regularly send slim products through the post. For example, online retailers can use them for accessories, stationery, photographs and suitably sized craft items.

The plain brown surface provides space for address labels, barcodes and handling instructions. Consequently, businesses can integrate the cartons into established stock-control and dispatch processes.

Retailers may also use them for click-and-collect orders or product presentation. Meanwhile, offices can use the cartons to organise documents, samples, cards and other flat materials.

The slim profile can help businesses avoid oversized packaging for shallow products. Nevertheless, the completed parcel must still protect its contents throughout the expected delivery journey.

Where appearance matters, apply labels neatly and avoid unnecessary tape across customer-facing surfaces. Additionally, consider placing the carton inside an appropriate outer mailer if the kraft finish must remain clean.

We deliver these cartons to UK mainland addresses. Therefore, customers can include this format in purchasing plans for different offices, shops and packing stations.

Storing Single Wall Cartons 218x160x20mm

Store unused Single Wall Cartons 218x160x20mm indoors in a clean, dry and well-ventilated area. Additionally, keep the cardboard away from floors and walls where it could absorb moisture.

Protect the cartons from:

• Rain and condensation
• Damp floors and walls
• Excessive humidity
• Direct sunlight
• Naked flames and ignition sources
• Hot surfaces
• Oils and solvents
• Aggressive chemicals
• Dust and dirt
• Crushing pressure
• Rodents and other pests

Moisture can soften cardboard and reduce its structural performance. Therefore, never use a damp carton for an application that relies on dependable postal protection.

Store unassembled cartons flat and support them evenly. Otherwise, leaning or poorly supported bundles may bend, crease or develop distorted panels.

Because the cartons have a shallow profile, damaged folds can affect assembly and closure. Consequently, staff should handle unopened stock carefully.

Good stock rotation also helps maintain packaging quality. Use older undamaged stock before opening newer bundles.

Alternative Names for Single Wall Cartons 218x160x20mm

Customers may also refer to this product as:

• Letterbox cardboard cartons
• 218mm x 160mm x 20mm boxes
• 8.6 x 6.3 x 0.8-inch boxes
• Shallow single-wall boxes
• Brown letterbox boxes
• Large-letter postal cartons
• Slim cardboard mailers
• Flat postal boxes
• Small book-wrap-style boxes
• Kraft mailing cartons
• Shallow e-commerce boxes
• Compact postal cartons
• Flat product boxes
• Single-wall mailing boxes

Although these terms can describe similar products, dimensions, construction and closure styles may differ. Therefore, confirm the 218mm x 160mm x 20mm size and single-wall construction when comparing alternatives.

In particular, Single Wall Cartons 218x160x20mm should not be confused with padded envelopes or flexible mailing bags. These cartons provide a more structured cardboard format for suitable contents.

Food Safety Information

Direct food-contact suitability has not been confirmed for this product. Therefore, do not place unpackaged food directly against the cardboard.

When packing food or confectionery, keep it completely enclosed within suitable food-contact packaging. Additionally, make sure the carton cannot puncture, contaminate or otherwise compromise the primary pack.

The carton may suit secondary packaging for properly sealed products. However, businesses should complete their own hygiene assessment and request current compliance documents where required.

Furthermore, cardboard can absorb liquids, oils and odours. Replace the carton if contamination, dampness or staining occurs.

PPWR Compliance Information

The EU Packaging and Packaging Waste Regulation, Regulation (EU) 2025/40, introduces requirements affecting packaging placed on the EU market.

However, compliance depends on the complete packaging system, supply chain, intended market and applicable implementation dates. Therefore, this description should not be treated as a declaration of PPWR compliance.

Businesses should assess the finished packaging configuration, including the carton, tape, labels, inserts and protective materials. Additionally, they should request current technical evidence before making regulatory or environmental claims.

Where suitable recycling services accept cardboard, remove incompatible components and keep the material clean and dry. Nevertheless, collection requirements can vary between local authorities and commercial waste providers.

Sample Requests

Samples may be available to help customers assess the cardboard construction, kraft appearance, folded dimensions and suitability for their products.

To request a sample, email sales@expresspackaging.co.uk or call 0121 622 2347.

When contacting us, provide the dimensions, weight and type of item you intend to pack. Therefore, our team can help identify whether this carton size may suit your application.

Customers can also use the same details to discuss stock availability, larger requirements and delivery to UK mainland addresses.

Illustration Only

Product images are for general illustration only. Consequently, the precise brown shade, board texture, fold style and finishing details may vary slightly between manufacturing batches.

The stated 218mm x 160mm x 20mm and approximately 8.6 x 6.3 x 0.8-inch measurements are nominal. Therefore, small manufacturing tolerances may apply.

Any products, labels, tape or protective materials shown in an image are for presentation purposes unless the product listing specifically states otherwise.

Request a sample before committing to an application where the exact internal fit, appearance or carton performance is critical. Additionally, test the complete packaging system under realistic handling, storage and delivery conditions.