How this calculator works
Carriers price a parcel on the greater of its actual weight and its dimensional weight, so a large light box is charged as though it were heavier. The dimensional weight is the parcel volume divided by a contractual divisor. US domestic carriers commonly use 139 cubic inches per pound, international services often use 166, and metric tariffs use 5000 or 6000 cubic centimetres per kilogram. A parcel that is 12 by 12 by 12 inches holds 1,728 cubic inches, which is 12.43 pounds at a divisor of 139. If the scale says 10 pounds, the billable weight is 12.43 pounds.
Formula
dimensional weight (lb) = length x width x height in inches / 139 (or 166). dimensional weight (kg) = length x width x height in centimetres / 5000 (or 6000). billable weight = the greater of dimensional weight and actual weight.
Worked example
A 12 x 12 x 12 inch parcel has a volume of 1,728 cubic inches. At the 139 divisor the dimensional weight is 1,728 / 139 = 12.43 pounds, which is 5.64 kilograms. A 10 pound parcel is therefore billed at 12.43 pounds. The same parcel under the metric 5000 divisor, which is 30.48 cm on each side and 28,316.8 cm³, gives 28,316.8 / 5000 = 5.66 kg.
Advertisement
Frequently asked questions
Which divisor does my carrier use?
Check the tariff, because carriers change it and some use different divisors for domestic and international services. The 139 figure is common in the United States, 166 is used for some international parcels, and metric tariffs usually use 5000 or 6000 cubic centimetres per kilogram.
Why is my billable weight higher than the scale weight?
The carrier charges the larger figure. Bulky, light parcels pay for the space they occupy, which keeps a truck from filling with air. Packing more tightly, or choosing a box that matches the contents, usually reduces the charge.
Do the dimensions include the box or just the contents?
Measure the outer box, including any bulges, handles or padding, and round each dimension up to the carrier's stated increment. Most tariffs measure the longest point on each side, not the nominal box size.
Is dimensional weight used for freight as well as parcels?
Yes, though freight often uses density and freight class instead. Less-than-truckload shipments are rated by class, which comes from density and handling characteristics, while parcel networks use a divisor like the ones on this page.