Dimensional Weight Calculator (DIM Weight and Billable Weight)
Enter your box's length, width and height and, if you have it, the actual weight. You'll instantly see the dimensional (DIM) weight, the billable weight your carrier will charge for, and whether you're paying to ship empty space.
Measure the packed box at its longest points, including any bulges. The calculation runs in your browser; your numbers are not sent to us.
Dimensional weight (per box)
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Enter length, width and height.
- Billable weight
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- Total (boxes: 1)
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- Volume
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Your result appears here once you enter the dimensions.
How to calculate dimensional weight
Dimensional weight turns the space a box takes up into a weight. Multiply the length, width and height of the packed box, then divide by your carrier's divisor (also called the DIM factor). In the US, parcel carriers measure in inches and divide by 139 to get pounds.
DIM weight (lb) = Length (in) × Width (in) × Height (in) ÷ 139In centimeters: Length × Width × Height (cm) ÷ divisor = kg (UPS lists 5,000 for some of its Air Freight services)
Example (assumption): a 16 × 12 × 10 in box is 1,920 cubic inches; 1,920 ÷ 139 = 13.81, which UPS and USPS round up to 14 lb.
Carriers round before they bill. UPS rounds each dimension to the nearest whole inch (1.00 to 1.49 counts as 1, 1.50 to 1.99 as 2) and increases any fraction of a pound to the next whole pound. USPS rounds each measurement up to the next whole inch and the result up to the next whole pound. This calculator shows the exact figure, so check your carrier's rounding before you quote a price.
Dimensional weight vs actual weight: which one you pay for
Your carrier compares the box's actual weight with its dimensional weight and charges for the greater of the two. UPS calls this the billable weight. USPS bases postage on the actual weight or the dimensional weight, whichever is greater, but only for parcels larger than 1 cubic foot (1,728 cubic inches) on the pages we read: commercial Priority Mail and Parcel Select Destination Entry.
Light but bulky products (pillows, toys, lampshades) are usually billed by size; small, heavy ones (tools, books, metal parts) by weight. DHL Express prices a large but lightweight shipment on the space it takes up and calculates volumetric weight for each piece in the shipment.
Why 139? Dimensional weight divisors by carrier
The divisor sets how much weight a carrier counts for a given amount of space. One cubic foot is 1,728 cubic inches; divided by 139, that's about 12.43 lb. So a one-cubic-foot box is billed as at least 12.43 lb (14 lb after rounding up), whatever is inside. A larger divisor means a lower dimensional weight for the same box.
| Divisor | Units | 1 cubic foot counts as | 1 m³ counts as | Where it's used |
|---|---|---|---|---|
| 139 | in / lb | ≈ 12.43 lb | ≈ 439 lb (≈ 199 kg) | USPS (commercial Priority Mail and Parcel Select Destination Entry, over 1 cubic foot), UPS packages, DHL Express (US) |
| 5,000 | cm / kg | ≈ 5.66 kg (≈ 12.49 lb) | 200 kg | Some UPS Air Freight services (for example UPS Air Freight Premium Direct) |
Divisors read on October 29, 2026 in the carriers' own guides: USPS Domestic Mail Manual 223 and 253, the UPS Rate and Service Guide (daily rates) and the DHL Express US Service & Rate Guide 2026. Negotiated contracts can use a different divisor; enter yours under "Another divisor".
How to lower your dimensional weight
- Pick the box for the product, not the other way round: an inch of empty space on every side adds up fast. Example (assumption): trimming a 16 × 12 × 10 in box to 14 × 10 × 8 in takes it from 1,920 to 1,120 cubic inches, or from 13.81 to 8.06 lb at ÷ 139, and below USPS's one-cubic-foot line.
- Ship soft goods (clothing, bedding, cushions) folded or vacuum-packed so the box can be smaller.
- Set a few standard box sizes for your best sellers, so you know the billable weight and the shipping cost before the order comes in.
- When an order has several items, compare one large box with two smaller ones; the single box isn't always cheaper.
- Measure the box after packing: a lid that bulges or tape that adds height counts in the carrier's measurement.
Set shipping rates by weight or size in your own store
In Favenda you set shipping rates by weight or by size and add a free shipping threshold. For international orders, DHL Express, UPS and FedEx are built in: labels print from the order screen and tracking updates automatically. Each order shows real profit after shipping and payment costs, so you can see whether your rates cover what you spend.
FAQ
What is dimensional weight?
Dimensional weight (DIM weight) is the weight a carrier assigns to a package based on its size: length × width × height divided by a divisor. If it's higher than the actual weight, you're billed for the dimensional weight. US parcel carriers use 139 for inches and pounds.
Does USPS charge dimensional weight on small boxes?
Not on the USPS pages we read. For commercial Priority Mail and Parcel Select Destination Entry, dimensional weight applies only to parcels larger than 1 cubic foot (1,728 cubic inches); smaller parcels are priced on actual weight. UPS says dimensional weight may apply to all of its domestic and international package services.
How do I calculate dimensional weight in cm and kg?
Multiply length × width × height in centimeters and divide by your carrier's metric divisor to get kilograms. UPS lists 5,000 for some of its Air Freight services (1 m³ counts as 200 kg). US parcel services publish their divisor in inches and pounds (139), so for those, measure in inches or use the divisor in your contract.
Do carriers round the dimensions and the weight?
Yes. UPS rounds each dimension to the nearest whole inch and any fraction of a pound up to the next whole pound. USPS rounds each measurement up to the next whole inch and the dimensional weight up to the next whole pound. This calculator shows the unrounded figure.