Our Royal Mail PiP Medium Parcel cardboard boxes are the ideal solution when you need more capacity than a Small Parcel, while still keeping packaging strong, presentable, and cost-effective. This range includes both single wall and double wall boxes, giving you the right balance of strength and weight depending on what you’re shipping.

All Medium Parcel boxes are delivered flat-packed to save storage space and assemble quickly with packaging tape. The single wall options are perfect for everyday e-commerce packing, while the double wall boxes add an extra layer of corrugated protection for heavier or more fragile items in transit.

Pricing in proportion (PiP) sizes

All of the boxes below fall into Royal Mail’s Medium Parcel category. Choose the closest internal size to your product for the safest, most cost-effective postage.

Key Benefits

• Royal Mail Medium Parcel compatible: all sizes listed fall into the PiP Medium Parcel category
• Single wall & double wall options: choose lightweight everyday boxes or heavy duty protection
• Strong corrugated board: reliable protection for e-commerce, storage, and removals
• Flat-packed delivery: saves storage and arrives ready to assemble
• Quick assembly: folds into shape easily and seals with tape
• Professional brown finish: clean kraft outer and inner for a neat presentation

Size Guide – PiP Medium Parcel Boxes

Single Wall Boxes

• 229x229x229mm: Internal size 229x229x229mm – Board grade: R flute 2.3mm – SKU: MCP-400528-PSUK & MCP-400528
• 254x254x254mm: Internal size 254x254x254mm – Board grade: R flute 2.3mm – SKU: MCP-400590-PSUK & MCP-400590
• 305x229x229mm: Internal size 305x229x229mm – Board grade: R flute 2.3mm – Multiscore: 76mm – SKU: MCP-403168-PSUK & MCP-403168
• 305x305x305mm: Internal size 305x305x305mm – Board grade: R flute 2.3mm – Multiscore: 152mm,229mm – SKU: MCP-400592-PSUK & MCP-400592
• 350x250x170mm: External size 350x250x170mm – SKU: MCP-MCPiP352-PSUK, MCP-MCPiP352-RM & MCP-MCPiP352
• 381x254x254mm: Internal size 381x254x254mm – Board grade: B flute 3mm – Multiscore: 127mm – SKU: MCP-400545-PSUK & MCP-400545
• 457x305x254mm: Internal size 457x305x254mm – Board grade: B flute 3mm – SKU: MCP-400556-PSUK & MCP-400556
• 457x305x305mm: Internal size 457x305x305mm – Board grade: B flute 3mm – Multiscore: 270mm,229mm – SKU: MCP-402070-PSUK & MCP-402070

Double Wall Boxes

• 229x229x229mm: Internal size 229x229x229mm – Board grade: B/C flute 6mm – SKU: MCP-BX-B-229x229x229-PSUK & MCP-BX-B-229x229x229
• 254x254x254mm: Internal size 254x254x254mm – Board grade: B/C flute 6mm – SKU: MCP-BX-B-254x254x254-PSUK & MCP-BX-B-254x254x254
• 305x305x305mm: Internal size 305x305x305mm – Board grade: B/C flute 6mm – SKU: MCP-BX-B-305x305x305-PSUK & MCP-BX-B-305x305x305

Product Details

• Material: Single wall or double wall corrugated cardboard (size and style dependent)
• Colour: Brown outer & brown inner
• Delivery format: Flat-packed
• PiP size: Medium Parcel
• Board grades: R flute 2.3mm, B flute 3mm, or B/C flute 6mm (size and style dependent)
• For size guidance only this would replace the Kite Packaging codes: CSW090909, CSW101010, CSW120909M, CSW121212M-P30, CSW151010M, CSW181210, CSW181212M_P30, CDW101010, CDW121212M, CDW121212M-P30, CDW090909

Please note: Dimensions may vary slightly (±10–20mm) due to manufacturing tolerances. A sample service is available for testing prior to bulk orders. Branding/barcodes may appear on parts of the cardboard box. Images are for reference purposes only and there may be slight variances to the product supplied.

All of our products are manufactured and dispatched right here in our own UK warehouse, which means we can offer some of the fastest turnaround times in the country. And because everything is produced in the UK (unlike many other providers), you’ll never have to worry about customs delays or surprise charges. Delivery is calculated at checkout based on order value - free over £100, from £6.95 under that or select Next Day delivery upgrade for only £9.95. All orders are shipped flat-packed for maximum efficiency.