Shipping & Fulfillment

# Shipping: Dimensional Weight Errors Can Cost Big Bucks

There are mistakes that can cost you when calculating shipping and handling fees. A big one is missing a UPS, FedEx or U.S. Postal Service DIM (dimensional) or oversize rule for large or lightweight packages.

The term “DIM” refers to package shipping density, meaning the weight of the package in pounds per cubic foot. If your package is big enough, or if the weight is small enough, the DIM rules can make your shipping costs dramatically increase.

For example, to ship a carton as small as 18” x 18” x 18”, UPS and FedEx DIM rules substitute 31 pounds as the minimum billing weight, even if the actual weight is much less. Or, for a carton as small as 27” x 27” x 27”, UPS and FedEx will add a \$45 oversize surcharge on top of the DIM weight.

### How UPS and FedEx DIM Rules Work

If the shipping carton exterior dimension (length x width x height) volume is greater than 5,184 cubic inches (3 cubic feet), divide the carton volume by 194. The resulting number is the arbitrary DIM weight, which becomes the billable weight if it exceeds the actual weight.

For example, assume there’s a box with a volume of 36″ x 24″ x 12″, which is 10,368 cubic inches. Divide this volume, 10,368 cubic inches, by 194 equals a DIM weight of 54 pounds. If the actual ship weight is 10 pounds, the UPS or FedEx residential ground zone 5 delivery cost would be \$13.50; but, taking into account the 54 pound DIM weight, the fee increases to \$36.36 – a cost increase of \$22.86, or 170 percent.

### DIM Rules Are Different for Air Shipments

For UPS and FedEx air-express shipments, the same DIM calculation process applies, but without the 3-cubic-foot minimum. That means a typical carton size like 12″ x 9″ x 6″ has a DIM weight of 648 cubic inches divided by 194, or 3.34 pounds, which rounds up to a 4 pound billable weight, even if the actual weight is much less.

### Additional Fee For Oversize Cartons

There is a special UPS and FedEx rule for oversize packages, which is defined as length (the longest side) plus the girth (width x 2 plus height x 2) totaling more than 130 inches, but less than a 165 inch maximum size limit. A \$45.00 surcharge is added to the DIM or actual weight delivery cost for such oversize packages.

### U.S. Postal Service Priority Mail Rules Are More Complicated

For U.S. Postal Service Priority Mail zones 1 through 4, the minimum DIM weight is 20 pounds if the length plus the girth add up to more than 84 inches, but less than the 108 inch maximum size.

There is a different rule for Priority Mail zones 5 through 8. If the package volume exceeds one cubic foot (1,728 cubic inches), divide the cubic inches (L x W x H) by 194 to get the DIM weight. But, importantly, note that all U.S. Postal Service provided Priority Mail and Flat Rate cartons are excluded from the DIM rules.

For example, for a Priority Mail package that weighs 9 pounds with a length of 60 inches, width of 8 inches and height of 6 inches, the DIM weight for zone 1 through 4 is 60″ + (2 x 8″) + (2 x 6″) = 88 inches, which exceeds the 84 inch benchmark, making the DIM billable weight 20 pounds, far exceeding the actual weight of 9 pounds.

For the same size Priority Mail package sent to zone 5 to 8, the DIM weight calculation would be 60″ x 8″ x 6″ = 2,880, which divided by 194 equals 15 pounds billable weight and takes the place of the 9 pound actual weight.

### U.S. Postal Service Parcel Post Rules Are Even More Complicated

For U.S. Postal Service Parcel Post packages, there is a 20 pound minimum if the combined length plus girth exceed 84 inches, but is less than 108 inches. If the length plus girth exceeds 108 inches, but is less than the 130 inch size limit, you must use U.S. Postal Service oversized rates, which range from \$61.80 for zones 1 and 2 to \$107.16 for zone 8, regardless of the actual weight.

### The DIM Factor for International Shipments

For U.S. Postal Service, UPS and FedEx international packages, including UPS and FedEx ground-Canada shipments, the DIM factor used is 166 rather than 194. For example, for an international package sized 14″ x 12″ x 9″, the DIM weight works out to 1,512 cubic inches divided by 166, which equals 9.1 pounds, and rounds up to a minimum billable weight of 10 pounds.

### A Spreadsheet Makes Rate Shopping Easier To Manage

To use the spreadsheet, enter the length (the longest side), the width and the height in inches for each of your stock shipping cartons, rounding fractions up or down to an even inch. The resulting DIM weights and oversize fees are displayed for each domestic carrier and delivery type.

### More DIM Resources Are Available Online

If you would like to learn more about DIM calculation rules and pricing, here are some informative web pages.