When your package is large but not that heavy, it could get charged based on the dimensional weight (or DIM weight) instead of the actual weight 🙈 This can typically happen when you're shipping items like pillows, wreaths, or a handbag.
DIM weight can apply to any domestic package that is larger than 1 cubic foot (for example, if the dimensions are 12x12x12" or larger). For USPS, these surcharges will apply only to weight-based Priority Mail, Priority Mail Express, and Parcel Select Ground...and for UPS, they apply to all services except for Ground and 3 Day Select 👍
Calculating DIM weight
To determine if DIM weight pricing will apply to your shipment, multiply the Length * Width * Height of your shipment, and divide that total by 166 ✏️ If the number you get is higher than the actual weight of your shipment, USPS will use that number as the "dimensional weight" of your package when determining the cost of postage.
A quick example
Let's imagine we've got a box measuring 26x26x5" that weighs 3 lbs, being sent from New York to Los Angeles. The Priority Mail rate for this shipment would cost $65.22 😮
By multiplying the dimensions (26 * 26 * 5), the total we get is 3,380
When dividing 3,380 by 166, we receive a total of 20.4
Because 20.4 is higher than the original weight of 3 lbs, USPS will calculate the rate of this shipment as if it weighed 20.4 lbs
How can I avoid DIM weight pricing?
USPS no longer offers a way to avoid those dimensional weight surcharges, even if you choose to ship directly from the Post Office 😥 However, there are still ways to help reduce your cost to ship!
Use the smallest packaging possible for the item you're sending
See if you can cut your box down to a smaller size
If possible, separate the items being sent into multiple, smaller shipments
If the box can fit inside of an envelope or poly mailer with room to spare, see if you can find a lower rate through the "box in a bag" trick
UPS handles DIM almost exactly the same as USPS
DIM for UPS shipments works almost identically to DIM for USPS.
UPS uses the same divisor as USPS (166), which means that the math stays the same as it does for USPS shipments. However, unlike USPS, UPS applies DIM charges to both domestic and international shipments. For domestic shipments, UPS uses 166 as the volumetric divisor when calculating DIM. For international shipments, they use 139 as the divisor (so, DIM charges on international packages are even more expensive).
Another difference is that UPS only waives dimensional weight for packages that are less than 1728 cubic inches (1 cubic foot) for the domestic services Ground and 3 Day Select.
That means that for Ground and 3 Day Select services only, if your package's Length x Width x Height is 1728 cubic inches or more, divide the cubic volume by 166 to determine the minimum billed weight. That new weight is what will used to determine the cost of shipping.
For all other domestic UPS services (like 2nd Day Air, Next Day Air, etc.) there is no size threshold. So, dimensional weight will be taken into account even if your package is smaller than 1 cubic foot (1728 cubic inches), and applied if it leads to a "heavier" weight than the actual weight. Basically, even if your UPS package is tiny, if it's super lightweight then the DIM weight will probably be heavier, and that's the rate you'll pay for 😅
Still sailin' in murky waters? Our support team is happy to help 😃