How to Measure a Cardboard Box for Custom Sizes

JETBOX Guide to Box Measurements

Internal vs External Dimensions

Understanding the difference between internal and external dimensions is essential for ensuring your custom box is perfectly suited to your needs.

Internal Dimensions:

These refer to the usable space inside the box, which is critical for protecting and fitting your items.

Why Important: When manufacturing custom boxes, internal measurements are used. JETBOX ensures that your specified dimensions are met by accounting for the board's thickness during the cutting, scoring, and slotting process.
Use Case: Internal dimensions determine how well your items fit, ensuring they’re snug and secure.

External Dimensions:

These measurements focus on the overall size of the box, which impacts storage, handling, and shipping.

Why Different: External dimensions aren’t used in manufacturing but help calculate shipping costs and meet carrier size limits.
Important Note: Always provide internal dimensions when ordering custom boxes.

Measuring Boxes in Millimetres

In Australia, we use millimetres for precise and consistent measurements across industries. This level of detail is crucial for manufacturing and ensures that your custom boxes are perfectly tailored to your needs.

Example Scenario:

Internal Dimensions: Fit a fragile electronic device securely, with padding to prevent movement.
External Dimensions: Optimise the package to meet carrier size limits and save on shipping costs.

By understanding these measurements, you can confidently make packaging decisions that maximise protection, cost-effectiveness, and shipping efficiency.

Steps to Measure the Internal Dimensions of a Box

Accurate measurements ensure the perfect fit for your contents and streamline the customisation process. Here’s how to measure your box:

Materials Needed

Measuring tape or ruler
Notepad and pen
Flashlight (optional, for better visibility)

Step 1: Prepare the Box

Empty the box and remove any contents.
Fully open the flaps or lid to access the internal space.
If required, carefully unfold glued sections to lay the box flat, with the outside facing down.

Step 2: Measure the Length

Identify the longest internal side of the box.
Place your measuring tape or ruler inside, along the middle of the score (crease).
Measure from one end to the other and record the measurement in millimetres.

Step 3: Measure the Width

Locate the shorter internal side of the box.
Use the same process as for the length, measuring across the middle of the score.
Record the width in millimetres.

Important: Do not include the flaps in this measurement.

Step 4: Measure the Height

Measure from the bottom inside crease (score) to the top inside edge of the box.
Ensure flaps are not included in the measurement.
Record the height in millimetres.