extra large postage box

An extra large postage box is a strong cardboard box sized for bulky, long or awkward orders that no longer fit standard letter and parcel bands, so the contents can travel with proper protection and clearance. Custom Postal Boxes makes an extra large postage box to the dimensions your product needs, with custom printing, low minimum order quantities, free design support and free UK delivery.

When an order needs an extra large postage box

Standard Royal Mail bands top out at the medium parcel, which allows up to 61 cm in length, 46 cm in width and 46 cm in depth, with a weight limit of 20 kg. Anything longer, wider, deeper or heavier than that moves beyond the standard bands and needs either a large parcel service or a courier, and it needs a box built for the job. Typical loads include framed prints, lamps, board games in bulk, sports kit, homeware sets, tools and multi item orders that cannot be split sensibly.

Our heavy duty shipping boxes and double wall shipping boxes show the board strengths usually chosen at this size, and cardboard shipping boxes cover the wider shipping range for smaller loads.

Measuring bulky and awkward products correctly

Measure the longest side first, because carriers and postal services classify large parcels by their greatest dimension and often by a combined length and girth figure as well. Measure the product in the position it will travel in, including stands, handles or packaging that cannot be removed. Then add clearance for cushioning on every side, because a large item that touches the box walls transfers every knock straight into the product.

Why weight distribution matters at this size

In a large box, a heavy item that sits in one corner can tear a hand hole, burst a seam or tip the parcel during handling. Centre the weight, support the base with the strongest panel downwards and fill empty corners so the load cannot shift. If one item is far heavier than the rest, pack it lowest and closest to the centre of the base.

Board strength, sealing and protection for large parcels

Double wall corrugated board is the usual starting point for an extra large postage box, because larger panels flex more than small ones and the contents are often heavier. Corners and edges need the most help, so add corner protection for framed or rigid items, wrap fragile surfaces separately and use paper fill to stop movement without adding unnecessary weight. Seal every seam with wide strong tape and tape across the centre join as well as the edges, because large lids carry more strain when the parcel is lifted.

Labels and handling marks that actually get seen

Place the address label on the largest flat panel, away from tape joins and edges, and add handling marks where the carrier will see them during lifting. A second label or a copy of the address inside the box helps if the outer label is damaged. Check the packed size and weight against the Royal Mail guidance on sending parcels for standard services, and confirm large parcel limits with your chosen carrier before printing labels, because each service sets its own maximums.

Ordering an extra large postage box in the UK

Custom Postal Boxes is a project of Vertex Packaging, based in Wolverhampton and manufacturing in house. Because oversize boxes are made to order, you can match the internal dimensions to the product rather than padding out a stock size that almost fits. Pricing depends on size, material and quantity, so request a quote through our contact page with the product dimensions, packed weight and quantity. Sellers reviewing packaging waste duties can also read the GOV.UK guidance on packaging producer responsibilities. For fully bespoke dimensions across a whole range, see our custom shipping boxes as well.

FAQs about an extra large postage box

What counts as an extra large postage box?

A box counts as extra large when the packed parcel exceeds standard medium parcel limits, which are 61 cm long, 46 cm wide and 46 cm deep up to 20 kg with Royal Mail. Beyond those limits the parcel usually travels on a large parcel or courier service with its own size rules.

How do I measure a bulky item for its box?

Measure the length, width and height of the item in the position it will travel in, including any parts that cannot be removed or folded. Add clearance on every side for cushioning, then use those internal box dimensions when you request a quote.

What board strength suits a large postage box?

Double wall corrugated board suits most large and heavy orders because larger panels flex more and loads are usually greater. Very heavy or fragile items may need extra corner protection and internal supports, which can be planned when the box is specified.

Can an extra large postage box be printed?

Yes. Large panels carry logos, handling guidance and branding well, and print can help warehouse and delivery teams identify contents quickly. Keep the main address label area clear in the artwork so labels sit flat and nothing important is covered.

Should I split a large order into two parcels instead?

Splitting can help when one item is much heavier than the rest or when a single parcel would pass a carrier size limit. Compare the total cost and damage risk of both options, because two smaller well packed parcels sometimes travel more safely than one overstretched box.