How to Choose the Right Mailer Box Size

Choosing the right mailer box size starts with the product and everything that will travel inside it. A useful measurement brief distinguishes the product’s dimensions from the required internal box dimensions and records the unit used. Include protective wrap, inserts and accessories in the pack-out plan. The examples in the product grid link to existing packaging products; their specifications should be checked individually rather than treated as standard sizes for every order.

Measure the product before choosing a mailer box

Measure length, width and height at the product’s widest points. Include fixed caps, handles or protrusions that remain attached when packed. Record whether the figures describe the bare product or a wrapped item, and label the units clearly as millimetres, centimetres or inches. If the product is irregular, provide a photo and note which faces need protection or support.

For more than one item, measure the complete arrangement as well as each individual item. A set may need a divider or insert, and the insert can change the usable space. Do not add a guessed allowance without explaining the pack-out: the team can review the intended fit and discuss suitable clearance for the actual structure.

Account for inserts, closure and shipping

Draw or photograph how the products sit in the box, including any partitions, wrap or documents. Note the opening direction, closure style and whether the box will be shipped alone or packed into another carton. These details help distinguish internal dimensions from outside dimensions and flag any storage, shelf or parcel limits that should be reviewed before a size is approved.

After a structure is selected, ask for a dieline or drawing that shows the dimensions being quoted. Compare it with the product and pack-out, not just the outside appearance. Use the approved proof to check orientation and any artwork that relies on a particular panel size. Keep the final drawing with the order so future reorders use the approved specification.

Turn the measurements into a complete quote

Include the dimensions, measurement units, product weight if known, quantity, board or finish preferences, artwork status and delivery postcode. The published minimum order is 100 boxes per size and design, so list each size separately when the project includes multiple variants. The quote can then identify which specification and quantities it covers.

Ask for a written schedule based on the final dimensions, quantity and delivery destination. Confirm the final size and charges in the quote. Do not rely on a generic size chart if the product, insert or transport route has special requirements; the approved drawing and specification should describe the box you intend to order.

Related packaging guidance

• Mailer boxes — Browse mailer products after preparing your measurements.
• Postal boxes — Compare other listed products used for shipping briefs.
• Get a quote — Send dimensions, quantity and delivery details for review.

Mailer Boxes products

• Custom Mailer Boxes — Plan custom mailer boxes around the item going in the parcel, how it is packed and the artwork you want customers to see.
• Flat Pack Boxes — Flat Pack Boxes planned around the assembled size, product and dispatch route. Send dimensions, closure, quantities and artwork for a specification-led quote.
• Archive Boxes — Archive boxes planned around document size, file arrangement, labelling and where the packed boxes will be stored.

Request a packaging quote with your dimensions, quantity and artwork details.