Dimensional weight is calculated by multiplying box length x width x height (in inches) and dividing by a carrier divisor: 139 for UPS and FedEx domestic, 166 for USPS, or 194 for some international services. If the resulting DIM weight is greater than the actual weight, carriers bill you on the higher number. Right-sizing the box is the easiest way to lower shipping cost.
Dimensional weight estimates how much space a parcel takes up. Use it to avoid choosing a box that is much larger than the product needs.
Billable weight estimate
13 lb
Dimensional weight: 13 lb. Actual weight: 8 lb.
Use the smallest safe box size and compare mailers when the item is flat or flexible.