How to measure a box
Length, width, height: it sounds simple, but one wrong centimetre is enough for the product not to fit. Here is how to do it.
Updated 16 October 2026
The order of the dimensions
Box dimensions are always written in the same order: length × width × height, in centimetres.
- Length: the longer side of the opening.
- Width: the shorter side of the opening.
- Height: from the bottom to the opening.
For example, 40 × 30 × 20 cm is a box 40 long, 30 wide and 20 high.
Inside and outside dimensions
Inside dimensions tell you how much room there is in the box: they are what matters for the product to fit, and they are what we ask for on the website.
Outside dimensions are slightly bigger, because the thickness of the board is added. For example, for a double wall slotted box we allow about 1 cm more on length and width and 2 cm more on height; with single wall about half that.
If the box has to fit a specific space, such as a shelf, a pallet or a courier limit, also tell us the outside dimensions you must not exceed.
How much room to leave
- Measure the product at its widest points, including caps, handles and anything that sticks out.
- Add about 1 cm per dimension if the product goes in on its own or is already in its packaging.
- Add more if you put bubble wrap, paper or other protection around it.
- Do not overdo it: more empty space means more filler and a product that moves during the journey.
Let the website do it
In Design your box you enter the inside dimensions and see the box in 3D straight away. The website stops you if a dimension goes beyond the limits of the chosen style. If you only have the product dimensions, ask Tomi "Which box do I need?": it suggests a ready-stock box or a made-to-measure one with 1 cm of extra room.
Frequently asked questions
Are the dimensions on the website inside or outside?
Inside, in centimetres. We work out the outside dimensions based on the board.
What is the difference between length and width?
They are the two sides of the opening: length is the longer one, width the shorter. Height goes from the bottom to the opening.
What if I get the dimensions wrong?
Before production we make a sample: you can try your product inside and correct the dimensions.
Found the box you need?
Draw it with your own dimensions in Design your box and get a quote, or tell us what you need to pack or ship.