The dimensions of a box are based on the opening of an assembled box. The opening of a box is a rectangle; having two sets of parallel sides. The longer side is the length, the short is the width and the perpendicular side is the depth (internationally known as length, breadth and height). Boxes can be measured two ways:
Interior- dimensions of the interior of the box must be accurate in order to ensure proper fit of the product.
Exterior- dimensions of the exterior of the box are required mainly for palletizing and distributing the final boxed product.
Be sure to identify which box dimension is more important to your individual needs before designing the package, in order to make the most economical decision.