Understanding Box Packing Calculations

In some of our premium shipping methods — such as USPS, UPS, and FedEx — the boxes used to ship are automatically calculated based on dimensions of items in the customer’s cart.

This page details how shipping calculators work and ways you can ensure proper setup and calculation.

Product Dimensions vs. Shipping Dimensions ↑ Back to top

The most important part of all calculators is the individual product page – specifically, the “Shipping” tab available. There, you’ll see weight, length, width, and height, all in the units chosen in your WooCommerce Settings.

The standard product dimensions field. Shipping dimensions for variable products will be in each variation, or default back to this standard. Set per-product.
The standard product dimensions field. Shipping dimensions for variable products will be in each variation, or default back to this standard. Set per-product.

It’s important to realize that this area is where you input the shipping dimensions of the product, not the actual, laid out dimensions. Whatever size the item or package will be when it’s shipped will be what you input here, including any extra padding or wiggle room you choose to have.

As an example scenario, let’s say you’re selling movie poster One Sheets – laid out, these posters are 27″ wide, 41″ tall, and 0.01″ thick. However, if we entered those dimensions, we would need a box at least 27.01″ by 41.01″ by 0.02″ thick, something that would certainly result in wasted space and an extremely inflated fee.

Instead, you would likely roll the poster and place it in a tube. One Sheets are rolled so the smallest edge is the height – this means it will roll into a package approximately 27″ by 3″ by 3″. It would be circular, but by establishing these measurements, you’re sure that it fits into the tightest, most reasonable packaging possible.

Box Selection ↑ Back to top

For most methods, default box sizes will be used depending on the methods you select. These sizes can be found at the following websites.

Unless otherwise mentioned, you should assume dimensions given for the boxes are the outside dimensions. You’ll want something slightly bigger than your product, as a 12″ product will be larger than the 11.75″ interior dimension, due to the physical walls of the cardboard box.

Using Custom Boxes ↑ Back to top

In some methods, you can also use your own boxes and envelopes. For this, you’ll need to measure both the exterior dimensions of the packages at their widest points as well as interior dimensions and maximum weight. Note that these boxes will be used alongside the default boxes, not entirely in place of them.

How to see the Calculated Boxes ↑ Back to top

All shipping methods have a debug mode – this shows the information sent to and from the shipping provider’s calculator, along with what boxes were selected for shipping. The output will vary depending on the method. See the documentation covering Shipping Methods & Debug Mode here.

While Debug Mode is active, your customers will be able to see the same information you do. Be sure to disable debug mode when you’re finished.

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