Dimensional Weight Calculator
See the billable weight USPS, UPS, FedEx and DHL will actually charge for a box, using each carrier's current divisor and rounding rules.
Your numbers
Your result · updates as you type
Billable weight
15 lb
Dimensional weight (15 lb) is higher than the actual weight (4 lb), so you're billed for the box's size, not just its weight.
- Rounded dimensions
- 18 × 14 × 8 in
- Divisor used
- 139
- Extra weight billed
- 11 lb
Shrinking any one side lowers the cubic size fastest. A box that's mostly empty space is usually cheaper to downsize than to pack heavier.
Breakdown
- Cubic size (rounded sides)
- 2,016 cu in
- Dimensional weight (2,016 ÷ 139)
- 15 lb
- Actual weight (rounded up)
- 4 lb
- Billable weight (the greater of the two)
- 15 lb
How dimensional weight is worked out
Dimensional (DIM) weight estimates how much space a box takes up on a truck or plane, and carriers bill whichever is greater: the actual scale weight or the dimensional weight. A big, light box can end up costing as much to ship as a small, heavy one.
Example: an 18 × 14 × 8 in box weighing 4 lb
- Cubic size
- 18 × 14 × 8 = 2,016 cu in
- Divisor (UPS/FedEx account rate, or USPS Priority)
- 139
- Dimensional weight
- 2,016 ÷ 139 = 14.5, rounded up to 15 lb
The box is billed at 15 lb, not its actual 4 lb, because dimensional weight is the higher of the two.
- USPS Priority Mail / Priority Mail Express: divide by 139, but only when the box is over 1 cubic foot (1,728 cu in). Smaller packages are billed by actual weight.
- UPS and FedEx, account or Daily Rates: divide by 139. Both carriers moved from 166 to 139 for US domestic and export shipments in January 2017.
- UPS retail (walk-in counter) rate: still divides by 166, a higher divisor that produces a lower DIM weight than the account rate.
- DHL Express: bills in kilograms using length × width × height in centimeters ÷ 5,000. That works out to about the same result as dividing inches by 139, which is what this calculator shows for comparison.
Using this on Shopify or WooCommerce
If you print labels through Shopify Shipping, ShipStation, Pirate Ship or a similar tool, the dimensional weight is calculated for you at checkout, using the box dimensions you enter. This calculator is for planning ahead: sizing new packaging, or checking a rate before you commit to a box.
- Enter the box you actually pack, not the product's dimensions. Add an inch or two for padding before you compare.
- If dimensional weight is driving your cost, see the box size calculator for the smallest standard box that still fits the item.
- For a UPS or FedEx package, also check the surcharge checker: oversized boxes can trigger an Additional Handling or Large Package fee on top of dimensional weight.
Pitfalls
- Old advice still quotes 166. UPS and FedEx changed their US divisor to 139 in 2017. 166 now mostly applies to UPS's retail counter rate, not account shipping.
- Every dimension rounds up first. A 17.2 in side is billed as 18 in before the multiplication happens, not rounded to the nearest inch.
- International rates can differ. DHL and other couriers commonly use a metric 5,000 divisor; general air freight often uses 6,000. Use the volumetric weight calculator for centimeters and kilograms.
Questions people ask
What is the current dimensional weight divisor for UPS and FedEx?
139, for US domestic and export shipments billed at account or Daily Rates, since January 2017. UPS's retail counter rate still uses 166.
Does USPS use dimensional weight?
Priority Mail and Priority Mail Express use it, but only for packages over 1 cubic foot (1,728 cubic inches). Smaller packages are billed by actual weight.
Is dimensional weight the same as billable weight?
No. Dimensional weight is one number the carrier calculates from the box size. Billable (or chargeable) weight is whichever is higher: the dimensional weight or the actual scale weight.
How do I avoid dimensional weight charges?
Use the smallest box that safely fits the product. Every inch of unused space in a box adds to the cubic size, and therefore to the dimensional weight.
Related tools
Want this builtinto your store?
I'm Emmanuel, a Shopify and WooCommerce developer. If this tool pointed at something you'd rather have fixed for you (a faster store, cleaner product data, a migration, a custom feature), send me a note.
Emmanuel Asika
Shopify & WooCommerce developer, Dublin
I build and fix online stores: new builds, migrations, speed, SEO and the custom bits apps can't do.
Last reviewed 30 September 2026.
Sources: USPS: Priority Mail (dimensional weight formula and $100 included insurance) · DHL: How to calculate volumetric weight