Dimensional Weight Pricing

Dimensional weight pricing is calculated based on the dimensions of the package instead of the actual weight. This helps carriers manage the two main factors that affect shipping costs: package dimensions and weight.

Package dimensions are the length, width, and height of the parcel. These determine how much space the package takes up in the truck or airplane. The smaller each package, the more shipments can fit into the same space. Likewise, larger packages reduce the number of shipments each vehicle can transport.

Package weight directly affects how much fuel it takes to transport the package. Heavier packages cost carriers more in fuel than lighter ones.

Very large and very heavy parcels cost more to ship than very small and light ones. So, carriers use dimensional weight (also known as DIM weight) as a way to balance their shipping costs.

Things to know about dimensional weight pricing:

  • Dimensional weight pricing charges more for large packages that weigh very little

  • Dimensional weight pricing only applies to packages larger than 1 cubic foot.

  • Most packages are less than 1 cubic foot and are not subject to dimensional weight pricing.

Determining Dimensional Weight

DIM weight is calculated using the volume of the package (length x width x height). The volume is then converted to a dimensional weight using a carrier-specific divisor.

Each carrier has adopted a formula for determining what the dimensional weight is. This is the minimum shipping weight for a box over 1 cubic foot (1728 cubic inches).

If the rate for the dimensional weight is higher than the standard rate of the package, you will be charged the dimensional weight.

Stamps.com automatically compares the dimensions with weight to determine if dimensional weight pricing is needed, so there is nothing additional you need to do.

How big is one cubic foot?

One cubic foot is 12" x 12" x 12". Most boxes are not this large!

A common box size is the 18" x 16" x 6" box. When multiplying the length, width, and height of this box, it is 1728 cubic inches exactly - 1 cubic foot.

Any box smaller than this is less than one cubic foot and is not subject to dimensional weight.

USPS Dimensional Weight Formula

USPS considers dimensional weight when you send packages using Priority Mail, Priority Mail Express, or Ground Advantage (excluding Flat Rate boxes) to zones 5-9:

  • Shipments from the US to Canada: Multiply its length, width, and height. If the result is more than 1 cubic foot, divide that result by 139. This will help you figure out the dimensional weight.

  • Shipments to any other location: Multiply the package's length, width, and height. If the result is more than 1 cubic foot, divide that result by 166. This will give you the dimensional weight for shipping to other places.

UPS Dimensional Weight Formula

Dimensional weight can apply to any UPS service class:

  • Domestic services: Multiply the dimensions (Length x Width x Height), and if the result is more than 1 cubic foot, divide the result by 139 to determine the dimensional weight.

  • International services: Multiply the dimensions (Length x Width x Height), and if the result is more than 1 cubic foot, divide the result by 166 for Ground, Air, and Standard to Canada and 139 for all other services.

Dimensional Weight Pricing Example

Let's calculate a 14" x 14" x 10" package shipping to Zone 8 using USPS Priority Mail:

  1. Calculate the cubic volume: (14 x 14 x 10) / 1728 = 1.134, which is greater than 1. Since the package is more than 1 cubic foot…

  2. Convert dimensions into weight (14 * 14 * 10) / 166 = 11.8 lbs.

  3. Round up to the nearest pound for the DIM Weight. The DIM weight is 12 lbs.

Considerations for Dimensional Weight Pricing

To help manage shipping costs around dimensional weight pricing:

  • Examine your products and packaging. Use properly sized boxes. You should aim to use the smallest box (with the smallest volume) possible. Even trimming fractions of an inch in each dimension can save you on postage. This may also mean you will want to switch to more compact packing materials so that you are not wasting space.

  • If your box is less than 1 cubic foot, choose a Package option for your shipping service.

    Our software defaults all Package types to 1 cubic foot when no dimensions are entered for the shipment.

  • If your box is larger than 1 cubic foot, choose the Large Package option for your shipping service and enter the dimensions.

    Our software will compare the size, weight, and distance to calculate the rate required.

  • Always provide your package dimensions. If you forget to do so, you may be surprised by extra charges. If you ship a package larger than 1 cubic foot without entering dimensions, any dimensional weight charges will be subtracted from your account balance as an adjustment.

When you use Dimensional Weight Pricing, it is more challenging to figure out costs, especially if you offer free shipping. To know if it's okay for your business, look at where most of your customers are.

For example, if you're in California and sell warm clothes to people in Maine, the cost of shipping might be too much if you also want to offer free shipping and keep your prices fair. Checking these things can help you decide if free shipping works well for your business.

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