How to Choose the Right Size Shipping Box to Cut Dimensional Weight

What dimensional weight means for your shipping bill

Dimensional weight, often called DIM weight, is a pricing method carriers use to account for package volume. They compare the actual weight of a package to a weight calculated from its length, width and height, and bill you for whichever is greater.

The result is simple. A light product shipped in a large box can be billed as if it were much heavier. The formula and divisor vary by carrier and change over time, so check your carrier's current rules instead of relying on a number you remember.

• Billable weight is the greater of actual weight or dimensional weight.
• Light, bulky items are the most exposed to DIM charges.
• Heavy, dense items are usually billed on actual weight.
• Every inch you remove from a box dimension can reduce the billed size.

Measure the product the way you will actually pack it

Start with the packed product, not the bare product. Measure length, width and height of the item as it will sit in the box, including its retail packaging, inserts or sleeves. Write the numbers down in the same order every time so your box sizes stay consistent.

Then decide how much protection the item needs on each side. Sturdy goods may need only a small gap. Fragile goods need room for cushioning. Add that allowance to each dimension, and you have the interior size you are looking for.

• Measure length, width and height of the packed item.
• Add cushioning allowance on every side that needs it.
• Remember that box sizes are listed as interior dimensions: length x width x height.
• Round up to the nearest standard size rather than building around a custom one.

Aim for a snug fit, not a tight squeeze

A box that is too big wastes money on postage and void fill. A box that is too tight offers no protection and can bulge or burst at the seams. The goal is a snug fit with a small, controlled amount of cushioning.

A practical check: close the box and shake it gently. If the product shifts or rattles, there is too much space. If the flaps will not close flat, the box is too small.

• Too much space: higher DIM charges and more damage from movement.
• Too little space: crushed corners and bulging walls.
• Just right: product stays in place with a thin layer of protection around it.

Related: Shipping and protective packaging from American Price Mark

Pick the box style that matches the product

The standard regular slotted carton is the workhorse for most shipping, and it is available in a wide range of sizes. For flat items such as books, framed prints or apparel, a low-profile or mailer-style box can cut height and volume sharply.

Long, narrow products often ship better in telescoping boxes or tubes than in a large cube. If you ship a variety of items, a depth-scoring box lets you cut the height down to fit, so one stocked size can serve several products.

• Regular slotted cartons: general purpose, many sizes.
• Mailer boxes: flat or low items, less height.
• Telescoping boxes: adjustable length for long items.
• Scored or adjustable-depth boxes: fewer stocked sizes for mixed products.

Match board strength to weight, not just size

Right-sizing does not mean using thin cardboard. A smaller box carrying a heavy item still needs the board strength to hold it. Corrugated boxes are rated by edge crush test or burst strength, and the right rating depends on the weight of the contents and how the box will be stacked.

If you are shipping heavy goods, choose a stronger grade and consider double-wall construction. Saving a dollar on the box does not help if a failed carton means a replacement shipment.

• Lighter items: single-wall board is usually enough.
• Heavier items or stacking: higher-rated or double-wall board.
• Check the rating printed on the box certificate when ordering.

Related: Corrugated and shipping supplies

Reduce void fill and standardize your sizes

Once your boxes fit better, you need less void fill. Paper, air pillows and foam all add cost and labor. A well-sized box often needs only a little filler to keep the product from moving.

Standardizing helps too. Most operations are best served by a short list of box sizes that cover most orders. Fewer sizes mean simpler purchasing, easier storage and faster packing. Review your shipped orders every few months and see whether a new size would cover a recurring product.

• Pick a small set of sizes that cover most orders.
• Review order data periodically for patterns.
• Use the smallest filler that keeps the product from shifting.
• Train packers to choose the smallest box that fits.

Label your boxes clearly and get the supplies in one place

A correctly sized box still needs a readable label. Shipping labels, barcode labels and handling marks should sit flat on a clean surface, not across seams or edges. We are a Florida manufacturer with more than 40 years in the label industry, and we make custom and barcode labels for shipping operations. Proofs go out within 24 hours, and we are available 8am to 8pm, seven days a week.

For the boxes, tape, stretch film and other shipping supplies, our sister company American Price Mark carries a wide range at competitive prices.

Related: Barcode labels · Custom product labels · Get a free quote · American Price Mark packaging supplies

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