How To Measure A Box

Boxes are the initial level of protection against damage to your products whilst being handled, stocked, or shipped. Your products travel through several hands before they make their way to your customer’s front door. Choosing the right dimensions to effectively secure your product in transit whilst utilising the best shipping and volume configuration is an important consideration.

In order to ensure you know exactly what dimensions you require for your custom boxes, we've created these a guidelines on How to Measure A Box for easy reference. With this guide, you'll have no trouble getting the precise dimensions of any box, ensuring that your packing and shipping processes go smoothly.

Why do we use Millimetres?

In Australia, box dimensions are measured in millimetres (mm) due to the metric system. This ensures precision and consistency in manufacturing.

Internal vs. External Measurements


A very common mistake to make while measuring a box is using the dimensions of the outside of the box. This way of measuring the box does not properly account for the thickness of the corrugated cardboard. When measuring a box for custom manufacturing, it's important to focus on internal dimensions. These are the usable spaces inside the box where your product will fit. We use these internal dimensions to ensure that your box is built precisely to your specifications.

External dimensions, on the other hand, relate to the overall size of the box, which impacts shipping and storage but isn't used in the manufacturing process. Always provide internal dimensions when submitting your measurements. Interior measurements guarantee a perfect match for the product no matter how thick or thin the packaging walls are. Relying on the outside measurements can lead to boxes where your products will not fit inside the box. 

Internal Dimensions

Ensure the device fits snugly with padding.

External Dimensions

Make sure the box meets shipping carrier size restrictions.

Consider Your Product Size

A very common mistake to make while measuring a box is using the dimensions of the outside of the box. This way of measuring the box does not properly account for the thickness of the corrugated cardboard.

Interior measurements guarantee a perfect match for the product no matter how thick or thin the packaging walls are. Relying on the outside measurements can lead to boxes where your products will not fit inside the box. 

Steps to Measure

You will need to use a ruler or measuring tape to measure.

The order of measurements is Length x Width x Height with length being the longest dimension first. 

Remove any contents and fully open the flaps or lid. If the box is glued, carefully unstick the glue flap so the box can lay flat with the outside facing down.
The length of the box is the longest side when looking at it from the top. Place your measuring tape or ruler inside the box, at the centre of the score (the indented crease). Measure from one end of the inside score to the other, and record the length in millimetres.
The width of the box is the shortest side when looking at it from the top. Measure from one end of the inside crease to the other, in the centre of the score. Record the width in millimetres.
The height (or depth) is the side that’s perpendicular length and width. Place your measuring tape or ruler at the bottom inside score of one of the vertical sides. Measure from the bottom to the top inside crease, only from score to score, excluding any flaps. Record the height in millimetres.

Ready To Design Custom Boxes?

Boxes are the multi-tool of the product packaging world, making your products look good while protecting them from damage as they make their way to consumers. Measuring the dimensions of the boxes you’ll need for your product line is just the first step.  

We work with a range of businesses to create custom boxes that look great and provide plenty of protection during shipping. Build your own box online using our Box Builder tool or contact us today for a free no-obligation quote. 

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