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Getting your dimensions wrong is the single most expensive mistake in custom packaging. A box that is a quarter inch too small will not close. A box that is half an inch too big lets your product slide around and arrive damaged. Learning how to measure a box properly takes about five minutes, and it protects the entire order that follows. This guide walks you through the standard method, what to do when you have no existing box to copy, and the mistakes that cause most reprints.
Packaging dimensions are always written in the same order: length, then width, then depth. Write them any other way and you risk receiving a box turned on its side.
Length is the longer side of the opening.
Width is the shorter side of the opening.
Depth is the distance from the opening down to the base.
So a box written as 8 x 6 x 4 has an opening measuring 8 inches by 6 inches, and sits 4 inches deep. Depth is sometimes called height, and both refer to the same measurement.
This is the rule that catches people out. Custom packaging is specified by internal dimensions, because what matters is the space your product actually occupies.
Board has thickness, and that thickness varies enormously between materials. Cardboard adds very little. Corrugated adds considerably more because of the fluting between the liners. Rigid board is thicker again. If you send us external measurements, the finished interior will be smaller than you expect, and your product may no longer fit.
When in doubt, measure the inside and tell us that is what you have done. If you can only measure the outside, say so and we will adjust for board thickness on our end.
Record everything in inches to the nearest sixteenth, and measure each dimension twice. Two minutes of double-checking is cheaper than a full reprint.
This is the panel your product goes through. Every measurement is taken relative to it.
Run your tape across the longer side of the opening, from inside edge to inside edge.
Measure the shorter side of the opening the same way, inside edge to inside edge.
Measure from the inside of the opening straight down to the inside of the base.
If you are packaging something for the first time there is nothing to copy, so you work from the product itself.
Measure the product at its widest, longest, and tallest points, including any cap, lid, spout, or handle.
If you are packing multiple units in one box, arrange them exactly as they will sit and measure the whole group.
Account for anything going in alongside the product, such as tissue paper, a manual, a warranty card, or a promotional insert.
If you want a foam or cardboard insert, measure the product only and tell us, because the insert is designed around it.
Your box should not match your product exactly. A little breathing room lets the product go in and out without tearing the board or scuffing the print.
How much clearance depends on what you are packing and what the box is made from. A rigid retail box holding a cosmetic bottle wants a snug fit so nothing shifts on the shelf. A corrugated shipper carrying something fragile needs more space for cushioning. Inserts, dividers, and wrapping all add to the requirement.
Rather than guessing, send us the product dimensions and tell us what else is going in the box. Our team applies the right allowance for the material and style you have chosen, then builds the packaging template around it.
Different structures need slightly different attention.
Mailer boxes
Measure the internal base, then the depth to the point where the lid folds closed.
Tuck end boxes
Measure the opening face for length and width, then the full internal depth.
Two-piece rigid boxes
Measure the internal base tray. The lid is built to sit over it.
Magnetic closure boxes
Measure the internal cavity with the lid closed, not the flat panel.
Sleeve and tray boxes
Give us the tray dimensions and we size the sleeve to slide over it.
Pillow boxes
The curved shape makes depth hard to judge, so send your product dimensions and let us calculate the box.
Gable boxes
Measure the base footprint, then the height up to where the handle panels meet.
Always work from internal dimensions unless you tell us otherwise.
Rounding 6.4 inches to 6 gives you a box your product will not enter.
A foam insert can consume half an inch on every side.
Sending 4 x 6 x 8 instead of 8 x 6 x 4 produces an entirely different box.
If your product is handmade or the size fluctuates slightly, measure the largest unit you have.
Small, medium, and large mean nothing to a die cutter. Send numbers.
A crushed or damp box has already changed shape. Use a fresh one.
You do not have to be confident in your numbers before you contact us. Send what you have and we will confirm it.
Give us your product dimensions, or mail us a sample, and our team will work out the correct internal box size, factor in the board thickness for your chosen material, allow for any inserts, and build a free dieline template around the result. Before production starts you will receive a 3D proof showing the finished box, so you can check the fit visually while changes still cost nothing.
Accurate measurements are the foundation everything else sits on, and taking five minutes to get length, width, and depth right saves you from a box that will not close or a product that arrives broken. Send your dimensions to The Custom Pack and we will verify them, build your template free of charge, and produce your order with a minimum of 100 units, free US shipping, and a 12 to 14 business day standard turnaround. Need it sooner? Rush production runs 5 to 7 business days for a 25% expedited fee.
Send us your dimensions for a free size check and quote, or call +1 717 400 8990.