Dimensional Weight Calculator

Box size and scale weight in, DIM weight and the billable weight the carrier will charge out

Updated 2026-10-11

Carrier and divisor

Length (in)

Width (in)

Height (in)

Actual weight (lb)

DIM divisor (from your rate guide or contract)

Billable weight: 22 lb
Dimensional weight: 22 lb
Actual weight, rounded up: 9 lb
Billed on: Size: +13 lb over the scale weight
Measured box (rounded up): 18 × 14 × 12 in = 3,024 cu in
Volume: 1.75 cu ft
Tallest box billed at actual weight: 4 in high on the same footprint

Dimensional weight = L × W × H ÷ 139, each side rounded up to the next whole inch, result rounded up to the next pound. You pay for whichever is greater, dimensional or actual weight. Negotiated contracts often use a different divisor: enter yours above.

Your numbers stay on this device. The page link keeps your inputs, so a bookmark or shared link reopens these results.

Carriers charge for the space a parcel takes up, not just what it weighs. Enter the box size and the scale weight and the calculator returns the dimensional (DIM) weight and the billable weight, which is whichever of the two is higher. An 18 × 14 × 12 inch box holding 9 lb of product bills as 22 lb with UPS or FedEx, so you pay for 13 lb of air. The calculator also shows how short the box would need to be to bill at its real weight. Nothing is stored or sent.

How dimensional weight is calculated

Measure the length, width and height at their longest points and round each one up to the next whole inch. Multiply them to get the cube in cubic inches, divide by the carrier's divisor and round up to the next whole pound. That is the dimensional weight. The carrier bills the greater of the dimensional weight and the actual weight, also rounded up to the next pound.

Worked example: an 18 × 14 × 12 inch box is 3,024 cubic inches. 3,024 ÷ 139 = 21.76, which rounds up to 22 lb. If the packed box weighs 9 lb, the billable weight is 22 lb. Cut the box to 18 × 14 × 4 inches (1,008 cubic inches) and the DIM weight drops to 8 lb, so the parcel bills at its real 9 lb.

USPS works the same way for USPS Ground Advantage commercial parcels, with two differences. Dimensional weight only applies when the cube is over 1,728 cubic inches (one cubic foot), and a dimensional weight above 70 lb pays the 70-lb price. Since July 12, 2026 the divisor is 139, down from 166 (USPS Domestic Mail Manual 283, section 1.4.2).

Divisors at the time of writing (check your rate guide or contract)
Carrier and rate	Divisor	Applies to
UPS daily (account) rates	139	Every package
UPS retail counter rates	166	Every package
FedEx	139	Every package
USPS Ground Advantage commercial	139	Parcels over 1,728 cu in; 70-lb cap
International express, metric	5,000 (cm³ per kg)	Most air shipments

The same box with each divisor

The 18 × 14 × 12 inch box from the example (3,024 cubic inches, 9 lb actual) bills differently depending on the rate you ship on. A lower divisor means a heavier DIM weight.

18 × 14 × 12 in box, 9 lb actual weight
Divisor	Raw result	DIM weight	Billable weight
139 (UPS, FedEx, USPS)	21.76	22 lb	22 lb
166 (UPS retail)	18.22	19 lb	19 lb
194 (old USPS rule)	15.59	16 lb	16 lb

How to stop paying for air

DIM pricing punishes light, bulky parcels. The fixes are mostly about the box, not the product.

Stock three or four box sizes that fit your best sellers closely instead of one big box for everything.
Use mailers or poly bags for soft goods: a padded mailer has almost no height.
Measure after packing. A bulge in the lid adds an inch, and carriers round every fraction up.
Ask for a higher divisor when you negotiate. Moving from 139 to 166 cuts DIM weight by about 16%.
Compare carriers per box. A parcel under one cubic foot ships on actual weight with USPS Ground Advantage.

Metric: volumetric weight in kilograms

Outside the US, and for most international express shipments, the formula is length × width × height in centimetres ÷ 5,000, giving kilograms. A 50 × 40 × 30 cm box is 60,000 cm³, so 60,000 ÷ 5,000 = 12 kg. If it weighs 7.3 kg (7.5 kg rounded up to the half kilo), you are billed for 12 kg. Some carriers and freight forwarders use 6,000; enter your own divisor if your quote says so.

Frequently asked questions

How do I calculate dimensional weight?

Round each side up to the next whole inch, multiply length × width × height, divide by the carrier divisor (139 for UPS, FedEx and USPS Ground Advantage) and round up to the next pound. An 18 × 14 × 12 inch box is 3,024 ÷ 139 = 21.76, so 22 lb.

What is billable weight?

The weight the carrier charges you for: the greater of the actual weight and the dimensional weight, each rounded up to the next pound.

Does USPS use dimensional weight?

Yes, for parcels over one cubic foot (1,728 cubic inches). USPS Ground Advantage commercial parcels use a 139 divisor since July 12, 2026, and a dimensional weight over 70 lb pays the 70-lb price.

What divisor does UPS use?

UPS uses 139 for daily (account) rates and 166 for retail rates at the counter. Large shippers often negotiate a higher divisor, so check your contract.

How is volumetric weight calculated in kg?

Multiply the box size in centimetres and divide by 5,000 (some carriers use 6,000). A 50 × 40 × 30 cm box is 60,000 ÷ 5,000 = 12 kg.

Does dimensional weight apply to small boxes?

With UPS and FedEx it applies to every package, but a small dense box usually bills on actual weight anyway. With USPS it only applies above one cubic foot.

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