How to measure a box: length, width and height, in the right order

Length x width x height: which side is which

Box dimensions always refer to the opening, not to how the box sits on a table.

Here's where it goes wrong. Say you sell a candle in a tall tuck-end carton that opens at the top, 3 inches square and 5 inches tall. The opening is 3 x 3, so the box is 3 x 3 x 5. Order it as 5 x 3 x 3 and you get a carton that opens on its long side, which won't stand up on a shelf with the tuck on top.

Inside or outside dimensions

Box makers quote inside dimensions, because that's the space your product has to fit. Measure from inner wall to inner wall, with the tape pressed flat and the flaps open.

The outside is bigger by the board thickness on each side: barely anything for paperboard, roughly 1/16 inch per wall for E-flute corrugated and 1/8 inch for B-flute. Our materials overview shows which board goes with which box.

How to measure a box for shipping

Carriers work the other way around. They measure the outside, and they don't care where the opening is. Under the USPS Domestic Mail Manual, a parcel's length is simply its longest dimension, and girth is the distance around the thickest part. Most parcels can't go over 108 inches in length and girth combined.

Size also changes the price. UPS and FedEx bill whichever is greater: the actual weight or the dimensional weight, which comes from the outside size. UPS works it out as length x width x height divided by 139 on daily rates, then rounds up to the next pound, per its shipping dimensions and weight guide. So a 12 x 10 x 8 inch box bills as 7 lb, even with a 2 lb candle inside. Empty space costs money. Other carriers set their own divisors, so check theirs.

• Measure the outside of the sealed box, including any bulge.
• Length is the longest side, whichever way it faces.
• Girth is 2 x width + 2 x height, taken around the thickest part.

Measuring your product for a custom box

Here is how to measure box dimensions for a custom order: measure the product, not a box you already have. Then we work out the box.

• Measure at the widest point of each side. A pump bottle's widest point is the pump, not the bottle.
• Decide which way it goes in. That sets the opening, and so which numbers are length and width.
• Add anything that goes in the box with it: an insert, a card, tissue paper.
• Send the numbers in length x width x height order, or a photo of the product on a ruler.

Don't add clearance yourself. We add it when we draw the dieline, based on the board and any insert. Structural design is free, and the next steps are in how it works.

If a stock box already fits and you don't need it printed, buy stock. It's cheaper and faster. Custom pays off when the box has to fit tightly or carry your brand, as with custom kraft boxes or anything in our box range.