Dimensional Shipping Weight Calculator
Find the dimensional (DIM) weight of a box with the 139, 166, 5000 or 6000 divisor, compare it with the actual weight and see the billable weight.
Carriers bill light, bulky boxes by the space they take up rather than what they weigh. This calculator works out the dimensional (volumetric) weight of a package with the divisor your carrier uses, compares it with the actual weight and tells you which one goes on the invoice, for one box or a batch of identical ones.
How to use this tool
- Measure the length, width and height at the widest points, including any bulges.
- Enter the actual weight from your scale.
- Pick the divisor your carrier uses, or enter a custom one from your contract.
- Check the rounding assumptions against your service; USPS mode applies its July 2026 rule.
Formula
Dimensional weight = length × width × height ÷ divisor; billable weight = the greater of dimensional and actual weight
Divisors 139 and 166 work with inches and give pounds; 5,000 and 6,000 work with centimetres and give kilograms. The calculator converts your measurements to match the divisor, so you can enter either unit.
Example
A 12 × 10 × 8 in box weighing 5 lb, shipped with a 139 divisor: 12 × 10 × 8 = 960 cubic inches, and 960 ÷ 139 = 6.91 lb, which rounds up to 7 lb. That is more than the actual 5 lb, so the carrier bills 7 lb, and you pay for 2 lb of air. Ten of these boxes are billed as 70 lb.
Frequently asked questions
Which divisor does my carrier use?
UPS Daily and FedEx US parcel rates use 139; UPS Retail domestic uses 166. USPS Ground Advantage commercial changed to 139 on July 12, 2026. Metric 5,000 and 6,000 are selectable assumptions; confirm your contract.
Does USPS charge dimensional weight on small boxes?
USPS applies dimensional weight only to parcels larger than one cubic foot (1,728 cubic inches). The dedicated USPS mode applies this threshold and a 70 lb DIM price cap. It covers rectangular parcels, excluding cubic, ounce and oversized price calculations.
How can I lower the billable weight?
Use the smallest box that still protects the item and cut down oversized cartons. In the example, an 11 × 9 × 7 in box gives 693 ÷ 139 = 4.99, so it would bill at 5 lb instead of 7 lb.
What is the difference between DIM weight and volumetric weight?
They are the same idea. US parcel carriers say dimensional or DIM weight; air freight and international couriers usually say volumetric or chargeable weight.
Sources
Last updated: 2026