Cardboard boxes are available in single wall, double wall and triple wall construction — each designed for different weight ranges and protection levels. The range covers over 15 products across over 75 sizes, from small parcels through to large storage and shipping formats.
Single wall (B or C flute) handles most standard e-commerce dispatch up to 20–30kg. Double wall (BC flute) suits heavier items and stacked loads up to 40kg. Triple wall construction is used for industrial and pallet-level applications above 50kg.
Choosing the Right Wall Type
- Single wall (B/C flute) — lightweight, cost-effective, suitable for most e-commerce and postal applications up to 20–30kg.
- Double wall (BC flute) — greater stacking strength and impact resistance for heavier items, fragile goods or stacked pallets up to 40kg.
- Triple wall — maximum strength for industrial or very heavy loads above 50kg.
How to Measure a Cardboard Box
Box dimensions are always given as Length x Width x Depth (L x W x D) in mm, referring to the internal usable space. Measure your product at its widest points and allow 10–20mm clearance on each dimension for void fill or padding. External dimensions will be larger than stated internal dimensions — factor this in for pallet stacking calculations.
Royal Mail Size Guide for Cardboard Boxes
- Large Letter — maximum 353 x 250 x 25mm, up to 750g. Very few boxes fit this format; flat postal boxes only.
- Small Parcel — maximum 450 x 350 x 160mm, up to 2kg. Covers most standard e-commerce box sizes.
- Medium Parcel — maximum 610 x 460 x 460mm, up to 20kg. Larger shipping boxes.
Frequently Asked Questions
What is the difference between single wall and double wall cardboard boxes?
Single wall boxes have one layer of corrugated fluting sandwiched between two flat liner sheets (called B or C flute). They are lightweight and suitable for most standard postal and e-commerce applications up to around 20–30kg. Double wall boxes have two layers of fluting, giving significantly greater stacking strength and crush resistance — better suited to heavier items, fragile goods, or multiple-item cartons up to 40kg.
How do I choose the right size cardboard box?
Measure your product at its widest points (length, width, height). Add 10–20mm on each dimension for void fill or protective padding. Box dimensions are quoted as internal measurements — external sizes are larger. If you are shipping at scale and need to stay within Royal Mail or courier size bands, work back from the maximum external dimension and account for the wall thickness (typically 3mm single wall, 6mm double wall).
Are these boxes suitable for Royal Mail posting?
Yes. Single wall boxes within 450 x 350 x 160mm and under 2kg qualify as Royal Mail Small Parcel. Larger boxes fall into Medium Parcel (up to 610 x 460 x 460mm, 20kg). Flat postal boxes (large letter format) must be under 353 x 250 x 25mm and 750g. Always confirm packed weight and dimensions before selecting a postage rate.
Are the boxes recyclable or FSC certified?
Yes — cardboard boxes are fully recyclable through standard kerbside collection. FSC-certified options are available within the range — check individual product listings for certification details. Corrugated board is one of the most recycled packaging materials in the UK, with a recycling rate of over 85%.
Can I get custom printed cardboard boxes?
Yes — printed cardboard boxes are available. Contact the team for custom print options, minimum quantities and lead times. Custom printing is available for single colour flexo print through to full multi-colour options depending on specification.
