Measure a Regular Slotted Carton Shipping Box

How to measure a Regular Slotted Carton Shipping Box is a question that frequently comes up. The formula is simple: Length x Width x Depth, where the “Length” should always be the longer side of the box. To measure a box may seem very simple to some people, while it gets confusing to others. Keep in mind three important things:

  • Length x Width x Depth (height). With the assembled box and a measuring tape in your hands, determine the longest side of the box. Measure that side of the box, placing your measure tape horizontally inside the box. That will be your Length.

Now measure the inside of the smaller side of the box. It will be you Width.

Last, but not least, place your measure tape vertically from the bottom of the box, to the limit of the lateral wall. Do not include the flaps in this measurement and remember to always go from score (where the box folds) to score. That will show you the height, or the Depth of your box. Now that you already have the 3 measurements that you need, express them in this exact order: Length x Width x Depth.

See the example below:

18” x 12” x 9”. This box is 18 inches long, 12 inches wide, and 9 inches deep.

  • Have in mind that the box measurements always correspond to the inner dimensions of the box and you measure from score (where the box folds) to score. We do not measure the flaps of the box. In that way, it’s possible to ensure that the box will fit and protect your product comfortably. Be sure to allow a minimum of 1/8 of an inch extra to each dimension in order to have a snug fitting.

Note that the length and the width measures are supposed to correspond to the opening of the box. Remember that the length always corresponds to the longer side of the box, what that means is the length will always be longer than the Width.

Important: Do not measure the flaps of the box. Flaps are the parts that fold to close the box.

Last but not least, be sure you and your box provider are both using the   “Imperial”,  “English Measuring System”, which uses inches and feet. In the US, in most of the cases, boxes measurements are expressed in inches: E.G.:  The box on Step 1 measure is 18” x 12” x 9”, what that means is the box is 18 inches long, 12 inches wide, and 9 inches deep.

If you have a sample box in hand, and you would like to order more regular shipping brown boxes like the one you have, you can simply measure it open:

How to measure a regular shipping box open?

In order to measure an open corrugated box, first you have to fully open the carton until it becomes a flat cardboard sheet. Use the 3 Steps above, and be sure to write your measure in the formula: Length x Width x Depth (height), where the “Length” should represent the longer side of the box.  This type of measuring is very useful when quoting for Die-Cut Boxes, which is a type of box manufactured with the use of shaped die-cutting tools.

How to find the specs for a RSC – Regular Slotted Carton?

A Regular Slotted Carton is the most common type of corrugated box. There is no special tooling required to manufacture this style box.  RSCs can be measured by using the same 3 Steps above, and the formula: Length x Width x Depth (height).  Always measure using inside dimensions.

If you need further help to figure out how to measure your box, or if you would like to have information about any of our Packaging Solutions, please call 713.559.0570, or e-mail us at