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What is dimensional (DIM) weight and how does it affect my rates?

Created:   |   Updated:

Dimensional (DIM) 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 defined by 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 that 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 (DIM weight) as a way to balance their shipping costs.

TIP: if you ship small packages, find out if you qualify for discounted dimensional rates.

To better understand DIM weight, it helps to define the three types of weights that most carriers use:

  • Actual weight is measured with a standard scale. U.S. carriers measure actual weight in pounds and ounces.
  • 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.
  • Billable weight is the larger of the actual and DIM weight. It is used with the carrier's rate table to find postage costs.

Many major carriers, including USPS, UPS, and FedEx, have a set of DIM weight standards and rates.

Click through each section below to learn about the ways carriers handle dimensional weight.

Which carrier services are eligible for DIM weight?

Each carrier maintains their own guidelines for which shipments qualify for DIM weight.

USPS:

As of June 2019, USPS assesses DIM weight pricing for the following domestic package services:

  • USPS Priority Mail
  • USPS Priority Mail Express
  • USPS Parcel Select Ground (Retail Ground)

In addition, DIM weight only applies to shipments that meet these criteria:

  • Volume is greater than one (1) cubic foot, or 1728 cubic inches
  • Shipment for all domestic Zones

 

UPS:

Dimensional weight may apply to all UPS domestic and international, package and freight services.

 

FedEx:

FedEx assesses DIM weight pricing for the following U.S. (domestic) and international, package services:

  • FedEx Express
  • FedEx Ground

 

How do I find the billable weight of a package?

DIM weight is an important factor in finding the shipping cost for a package. The DIM weight is compared with the actual weight to find the billable weight. In the end, the billable weight determines how much it will cost to ship a package.

NOTE: be careful not to over pack boxes. Carriers may measure bulging packaging at the widest point on each side. This may cause the carrier's DIM weight calculations to differ from your own.

USPS:

  1. Calculate the cubic (volume) size of your package in inches.
    • Measure the outside of each side - length, width, height - to the nearest whole inch.
      For example: 20.25" rounds down to 20 inches, 20.75" rounds up to 21 inches (via USPS.com).
    • Multiply the length x width x height.
    • The total is the cubic size of the package.
  2. If the cubic size is less than 1,728 cubic inches (1 cubic foot):

    The actual weight of the package is the billable weight.

  3. If the cubic size is greater than 1,728 cubic inches (1 cubic foot):
    1. Find the DIM weight.
      • Divide the cubic size of the package by 166.
      • Round the weight up to the next whole pound. This is the DIM weight.
    2. Find the actual weight.
      • Use a standard scale to weigh the package.
      • Round the weight up to the next whole pound. This is the actual weight.
    3. Find the billable weight.
      • Compare the package actual weight to its DIM weight.
      • The larger of the two weights is the billable weight.
      • Use the billable weight with your USPS rate tables to find the postage cost.

Find an alternate method to calculate DIM weight for non-rectangular parcels.

 

UPS:

  1. Calculate the cubic (volume) size of your package in inches.
    • Measure the outside of each side - length, width, height - to the nearest whole inch.
      For example: 1.4 inches rounds down to 1 inch, 1.9 inches rounds up to 2 inches (via UPS.com).
    • Multiply the length x width x height.
    • The total is the cubic size of the package.
  2. Find the DIM weight.
    • Divide the cubic size of the package by 139.
    • Round the weight up to the next whole pound. This is the DIM weight.
  3. Find the actual weight.
    • Use a standard scale to weigh the package.
    • Round the weight up to the next whole pound. This is the actual weight.
  4. Find the billable weight.
    • Compare the package actual weight to its DIM weight.
    • The larger of the two weights is the billable weight.
    • Use the billable with your UPS rate tables to find the postage cost.
    • For multiple-package shipments, add the billable weight of all packages in the shipment.

 

FedEx:

  1. Calculate the cubic (volume) size of your package in inches.
    • Measure the outside of each side - length, width, height - to the nearest whole inch.
    • Multiply the length x width x height.
    • The total is the cubic size of the package.
  2. Find the DIM weight.
    • Divide the cubic size of the package by 139.
    • Round the weight up to the next whole pound. This is the DIM weight.
  3. Find the actual weight.
    • Use a standard scale to weigh the package.
    • Round the weight up to the next whole pound. This is the actual weight.
  4. Find the billable weight.
    • Compare the package actual weight to its DIM weight.
    • The larger of the two weights is the billable weight.
    • Use the billable with your FedEx rate tables to find the postage cost.
    • For multiple-package shipments, add the billable weight of all packages in the shipment.

 

Keep in mind, ShippingEasy will automatically run these calculations and comparisons for you. It's one of the many ways that ShippingEasy can save you time when shipping.

Start your 30-Day Free Trial with ShippingEasy.

 

What is the DIM weight of common package sizes?

This table shows the dimensional weight of popular package sizes.

* Where a DIM weight is not noted, the package is smaller than the carrier's threshold for dimensional weight.

DIM Weight of Package (lbs)
* package does not qualify for DIM weight; use actual weight.

Package Dimensions
(inches)

USPS

UPS

FedEx

4 x 4 x 4" * 1 1
5 x 5 x 5" * 1 1
6 x 4 x 4" * 1 1
6 x 6 x 4" * 2 2
6 x 6 x 6" * 2 2
8 x 6 x 4" * 2 2
8 x 6 x 6" * 3 3
8 x 8 x 4" * 2 2
8 x 8 x 6" * 3 3
8 x 8 x 8" * 4 4
9 x 9 x 9" * 6 6

Package Dimensions
(inches)

USPS

UPS

FedEx

10 x 8 x 6" * 4 4
10 x 10 x 10" * 8 8
12 x 6 x 6" * 4 4
12 x 9 x 3" * 3 3
12 x 9 x 4" * 4 4
12 x 9 x 6" * 5 5
12 x 10 x 4" * 4 4
12 x 10 x 6" * 6 6
12 x 10 x 8" * 7 7
12 x 12 x 4" * 5 5
12 x 12 x 6" * 7 7

Package Dimensions
(inches)

USPS

UPS

FedEx

12 x 12 x 8" * 9 9
12 x 12 x 10" * 11 11
12 x 12 x 12" 11 13 13
13 x 13 x 13" 14 16 16
14 x 10 x 6" * 7 7
14 x 10 x 10" * 11 11
14 x 14 x 6" * 9 9
14 x 14 x 10" 12 15 15
14 x 14 x 14" 17 20 20
15 x 15 x 15" 21 25 25

Package Dimensions
(inches)

USPS

UPS

FedEx

16 x 12 x 6" * 9 9
16 x 12 x 8" * 12 12
16 x 12 x 10" 12 14 14
16 x 12 x 12" 14 17 17
16 x 16 x 8" 13 15 15
16 x 16 x 16" 25 30 30
18 x 12 x 6" * 10 10
18 x 12 x 8" 11 13 13
18 x 12 x 10" 14 16 16
18 x 12 x 12" 16 19 19
18 x 14 x 12" 19 22 22
18 x 18 x 12" 24 28 28

Package Dimensions
(inches)

USPS

UPS

FedEx

20 x 12 x 12" 18 21 21
20 x 14 x 6" * 13 13
20 x 14 x 12" 21 25 25
20 x 16 x 14" 27 33 33
20 x 20 x 12" 29 35 35
20 x 20 x 20" 49 58 58
24 x 12 x 12" 21 25 25
24 x 16 x 16" 38 45 45
24 x 18 x 12" 32 38 38
24 x 18 x 18" 47 56 56
24 x 24 x 12" 42 50 50

Package Dimensions
(inches)

USPS

UPS

FedEx

48 x 4 x 4" * 6 6
48 x 6 x 6" * 13 13

What can I do to reduce the impact of DIM weight on my shipping costs?

Using the wrong sized package is costly for everyone. As a merchant, it means that you are paying too much for packing materials and postage. For carriers, it means that they cannot ship as many items with each truck and airplane load. Although it may seem like more to track, DIM weight incentivizes everyone to optimize packaging.

Here are a few strategies to mitigate the affects of DIM weight:

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.

Aim to use boxes that are less than 1 cubic foot. When you are shipping with USPS, this will allow you to avoid DIM weight all together. You may even qualify for lower cost dimensional (cubic) rates. Learn more about dimensional pricing.

Always provide your package dimensions. If you forget to do so, you may be surprised by extra charges.

  • On USPS shipments: USPS' Automated Package Verification (APV) system double checks that you pay the correct rate. Shipments with insufficient postage are invoiced by the USPS. When shipping via ShippingEasy, your USPS postage account will be automatically debited the difference. Learn about APV.
  • On FedEx and UPS shipments: you may find rate quotes differ from the postage billed on your invoice.

Save your custom package dimensions into your shipping solution. ShippingEasy makes this easy with the PACKAGE SETUP settings. Not only will you save time entering dimensions, but you can include the DIM weight in the package name. This will make it easy for you to match the right box with each shipment. Learn more about saving your custom packaging.

Use automation to streamline your packing decisions. ShippingEasy's Shipping Presets enable you to save combinations of carrier services and packaging. You can then use Shipping Rules to automatically assign your Shipping Presets to your orders. Learn more about using Shipping Rules to optimize packaging.

 

Examples of DIM weight vs actual weight for a USPS package:

12" x 12" x 12" package | Shipping to zone 5
DIM Weight: Actual Weight: Billable Weight:
  1. Calculate the cubic volume.
    (12 x 12 x 12) / 1728 = 1
    Package is 1 cubic foot.
  2. Convert dimensions into weight
    (12 * 12 * 12) / 166 = 10.4
  3. Round up to nearest pound.

    DIM Weight = 11 lbs

  1. Weight the package.

    Actual Weight = 14 lbs

  1. Find the greater of the actual weight and DIM weight.

    Billable Weight = 14 lbs

 

14" x 14" x 10" package | Shipping to zone 8
DIM Weight: Actual Weight: Billable Weight:
  1. Calculate the cubic volume.
    (14 x 14 x 10) / 1728 > 1
    Package is more than 1 cubic foot.
  2. Convert dimensions into weight
    (14 * 14 * 10) / 166 = 11.8
  3. Round up to nearest pound.

    DIM Weight = 12 lbs

  1. Weight the package.

    Actual Weight = 8 lbs

  1. Find the greater of the actual weight and DIM weight.

    Billable Weight = 12 lbs


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