Postal Boxes
Cardboard postal boxes sized for Royal Mail: slim letterbox boxes that post as a Large Letter, folding mailer boxes for Small and Medium Parcels, and book wraps.
Select Postal Boxes Product Range
3 Sizes AvailableSlim cardboard letterbox boxes designed to post as a Royal Mail Large Letter (up to 35.3 x 25 x 2.5 cm) and fit through most letterboxes.
7 Sizes AvailableDie-cut folding postal boxes that assemble without tape underneath, sized for Royal Mail Small and Medium Parcels.
2 Sizes AvailableWrap-around cardboard book mailers that hold books, folders and flat items firmly, with adjustable depth.
Engineering & Material Standards
Rigorous manufacturing specifications & quality controls
Slim boxes kept within Royal Mail's Large Letter limits of 35.3 × 25 × 2.5 cm, so they post at Large Letter rates and fit through most letterboxes.
Die-cut boxes that fold into shape without tape underneath, sized to fit Royal Mail Small and Medium Parcel bands.
Wrap-around boxes for books, folders and flat items, holding them firmly so corners stay protected.
This range is being set up with our supplier. Sizes shown are marked out of stock until they arrive. Contact us for availability and trade quotes.
B2B Trade & Bulk Ordering Benefits
Commercial trade terms, credit facilities & custom runs
Check every Royal Mail size and weight band before you choose a box.
The exact Letter and Large Letter limits, and how to stay within 2.5 cm.
Need a box today? Our single and double wall boxes include sizes that fit Royal Mail Small Parcel.
Looking for custom postal boxes sizing or pallet truckload quotes?
Our 24/7 AI Packaging Specialist and UK sales engineers provide instant calculations.