Packaging tools
Dimensional weight calculator
Carriers bill the greater of your box's actual weight and its dimensional weight. Enter your box and see exactly what you'll be charged for — before you buy the wrong size and pay to ship air.
You'll be billed for
How dimensional weight works
Shipping a light item in an oversized box means the carrier charges you for the space, not the weight — that's dimensional weight. The fix is almost always the same: use a box that fits. A snug, right-sized box lowers the billed weight and the cost on every parcel you send.
Common questions
What is dimensional weight?
Dimensional weight prices a shipment by the space it occupies rather than how much it weighs. Carriers multiply length by width by height and divide by a fixed divisor. If that number is higher than the actual weight, you're billed on the dimensional weight.
What is the DIM divisor for UPS and FedEx?
For most UPS and FedEx daily-rate accounts the divisor is 139. Retail or counter rates can differ, so check the rate table on your account. Both carriers round each dimension up to the next whole inch before calculating.
Does USPS charge dimensional weight?
USPS applies dimensional weight only to packages larger than one cubic foot (1,728 cubic inches) for most zones, using a divisor of 166 (139 effective Jul 12, 2026). Below that size, USPS bills actual weight.
How do I lower my dimensional weight?
Use a box that fits the item with minimal void space, remove excess height, and avoid shipping small items in large cartons. Right-sizing the box is the single most effective way to cut the billed weight.
Is billable weight the actual or dimensional weight?
Billable weight is whichever is greater. If your box is light for its size, you pay the dimensional weight; if it's dense, you pay the actual weight.