4.1 Dimensions are important properties in the general construction of a box, and accurate methods of measurement are required for research work, routine control, and acceptance testing for conformance to specifications. For packages to carry and protect their contents effectively and efficiently, boxes and interior components must be properly and consistently sized. Correctly dimensioned and well-made boxes can be more easily set up by hand or be erected using automatic equipment. "Square" boxes (rectangular parallelepipeds) will stack better to accept load and improve stability during storage and shipment.

4.1.1 Interior dimensions of boxes are critical when the contents of the box are intended to fill or nearly fill the box with little unused side and head space. The inside dimension by tape method are the size values most often cited in box design (see 9.1, and TAPPI T827). The interior size of a box can be estimated from the score to score measurements when the scoring allowance is taken into account (see Appendix X2). The actual inside dimensions can be measured directly using the box gauge method (see 9.2). Either method can be used to measure interior box dimensions.

4.1.2 Exterior dimensions may be the critical design criteria when attempting to optimize use of the shipping platform area and overall stack height based on transportation and storage limitations. Exterior dimensions are also key design elements when making common footprint boxes.5 The exterior dimensions of a box can be measured directly using the exterior dimensions by tape method (see Appendix X1).

4.2 Measuring a Lot Quantity of Boxes-This method determines if a lot (that is, production run) is within specified tolerance for each dimension (length, width, and depth as are shown in Practice D5118/D5118M). A minimum of five specimens are measured. The test result for each dimension is the individual measurements of that dimension on all specimens (see 9.3).

4.3 Measuring Single Boxes-Determines if one particular box is within specified tolerance for each dimension. The test result for each dimension is the average of all measurements of that dimension (see 9.4).