Postal Boxes

Choosing the right postal box

The most important factor is size — specifically, whether your packed box fits within a Royal Mail postal size band. Getting this wrong can add up to 40% to your per-item postage cost. Our Royal Mail size guide sets out the exact thresholds for large letter, small parcel, medium parcel, and large parcel, so you can match your box to the right band before you buy.

A few other things worth considering:

Peel and seal vs standard. If you're despatching at volume, peel-and-seal postal boxes save meaningful time on the packing line — no tape required. ColomPac are a popular choice here, with a range built around fast, efficient despatch.

White or brown. Brown postal boxes are the everyday workhorse. White postal boxes give a cleaner, more consumer-facing presentation — worth considering if your customer's unboxing experience matters to your brand.

Letterbox friendly. If you want to eliminate missed deliveries entirely, our letterbox-friendly boxes are sized to pass through a standard letterbox — no signature required, no redelivery cards.

Postal boxes and sustainability

All postal boxes in our range are made from recycled and responsibly sourced corrugated cardboard, and are fully recyclable at the end of their life — by you and by your customers. Using the right-sized box for your product also reduces void fill, cuts material costs, and means fewer wasted cubic metres on the delivery van.

For a full guide to cardboard box types, sizing, and what to look for when buying, see our complete guide to cardboard boxes. Or browse the full cardboard boxes range if you need something beyond postal and mailing boxes.