How to Choose the Right Shipping Box Size
The right shipping box saves postage and protects the goods. This guide shows how to match corrugated grade, internal dimensions and the girth limits of DHL and DPD, and when volumetric weight drives the postage class.
View shipping boxesWhich corrugated grade do you need?
The corrugated board decides how much stacking pressure and impact a box withstands. Single-wall boxes suit light to medium goods up to around 20 kg, while double-wall boxes are built for heavy or fragile shipments.
The flute type sets the thickness: C-flute (about 3.5 mm) is the standard for single boxes, B-flute (about 2.5 mm) is more crush and dent resistant, and the fine E-flute (about 1.5 mm) is used for printable retail packaging. Double-wall boxes usually combine BC.
- Single-wall: books, electronics accessories, light small parts up to about 20 kg.
- Double-wall (BC): heavy components, spare parts, bottles and impact-sensitive goods.
- E-flute: printable product and outer packaging for retail.
- Always select by bursting strength or ECT, not by wall thickness alone.
Why do internal dimensions matter, not external?
Manufacturer specs always refer to the internal dimensions in the order length x width x height. Only then does the contents fit safely. The external size is 5 to 15 mm larger depending on the board and is what counts for the carrier girth.
Allow roughly 2 to 4 cm all around for cushioning material. A box that is too large wastes filler and raises the volumetric weight, while one that is too small presses on the contents and lets the board crush at the edges.
How do girth and volumetric weight affect postage?
Carriers charge postage not only by weight but also by size. Girth is the longest edge plus twice the width plus twice the height. DHL caps a parcel at 300 cm girth and 120 cm longest edge, while DPD allows 300 cm girth and up to 175 cm longest side.
Volumetric weight applies when a box takes a lot of space at little weight. Calculation: length x width x height in cm divided by the divisor 5000 gives the volumetric weight in kg. The carrier bills the higher of actual weight and volumetric weight.
Frequently asked questions
Does the box size refer to internal or external?
The stated size is always the internal dimension in length x width x height. The external size is 5 to 15 mm larger depending on the board and counts for the girth.
How do I calculate volumetric weight?
Length x width x height in centimetres divided by 5000 gives the volumetric weight in kilograms. The carrier bills the higher of actual and volumetric weight.
What is the girth at DHL and DPD?
Girth is the longest edge plus twice the width plus twice the height. Both DHL and DPD allow up to 300 cm girth; above that the shipment counts as bulky goods.
Single-wall or double-wall?
Single-wall is enough for light goods up to around 20 kg, double-wall (BC) safely carries heavy or impact-sensitive items. The deciding factor is bursting strength or ECT, not wall thickness alone.
Looking for the right shipping box?
We supply single- and double-wall boxes in tested sizes including cushioning - matched to the girth and volumetric weight rules of the carriers.
Tested quality
Corrugated board selected by bursting strength and ECT.
Exact internal sizes
Dimensions clearly declared as length x width x height.
Postage in focus
Sizes matched to girth and volumetric weight.
Expert advice
Our team helps you pick the right box.