How is dimensional weight calculated?

Round each dimension up, multiply length × width × height for the cubic volume, then divide by the carrier's divisor (e.g. 139 for UPS/FedEx imperial). Billable weight is the greater of actual and DIM weight, rounded up to the next pound or kilogram.

What divisor does UPS use?

UPS uses 139 for US domestic Daily / commercial accounts and 166 for retail (UPS Store) shipments. The metric divisor is 5000 (cm³/kg). A smaller divisor produces a higher DIM weight.

What is billable weight?

Billable weight is the figure the carrier actually charges on — the greater of the parcel's actual weight and its dimensional weight, rounded up to the next whole unit.

Does USPS charge dimensional weight?

USPS applies dimensional weight only to parcels larger than 1 cubic foot (1728 in³) on applicable Priority Mail zones. Smaller parcels are billed by actual weight.

Dimensional (Volumetric) Weight Calculator

Enter a parcel's dimensions and actual weight to see the dimensional (DIM) weight for each carrier and the billable weight — the greater of actual and DIM. It shows instantly where you're paying for empty space, and which carrier is cheapest for this box.

Inputs

Your parcel

Units

Length (in)Width (in)Height (in)Weight (lb)

Carrier	Divisor	DIM weight	Billable
UPSUS domestic (Daily / commercial)	139	22 lb	22 lb
UPSUS retail (UPS Store)	166	19 lb	19 lbCheapest
FedExUS domestic & most services	139	22 lb	22 lb
USPSPriority Mail (over 1 ft³)	166	19 lb	19 lb
DHLExpress international	139	22 lb	22 lb

Highlighted = DIM weight is billed (heavier than actual).

For this parcel, UPS is cheapest at 19 lb billable.

How dimensional weight is calculated

Round each dimension up to the next whole unit, multiply length × width × height to get the cubic volume, then divide by the carrier's divisor. The billable weight is the greater of the actual weight and the DIM weight, rounded up to the next whole pound or kilogram. A smaller divisor means a higher DIM weight — so divisor 139 is more expensive than 166.

dim_weight = ceil(L) × ceil(W) × ceil(H) / divisor
billable   = ceil( max(actual_weight, dim_weight) )

Round each fractional dimension up before calculating (UPS & FedEx, 2025+).
Billable weight = max(actual weight, DIM weight), rounded up.
A lower divisor → higher DIM weight → higher cost. 139 is stricter than 166.
USPS only bills DIM for parcels larger than 1 ft³ (1728 in³).
Large shippers can often negotiate a more favourable (higher) divisor.

Frequently asked questions

How is dimensional weight calculated?: Round each dimension up, multiply length × width × height for the cubic volume, then divide by the carrier's divisor (e.g. 139 for UPS/FedEx imperial). Billable weight is the greater of actual and DIM weight, rounded up to the next pound or kilogram.
What divisor does UPS use?: UPS uses 139 for US domestic Daily / commercial accounts and 166 for retail (UPS Store) shipments. The metric divisor is 5000 (cm³/kg). A smaller divisor produces a higher DIM weight.
What is billable weight?: Billable weight is the figure the carrier actually charges on — the greater of the parcel's actual weight and its dimensional weight, rounded up to the next whole unit.
Does USPS charge dimensional weight?: USPS applies dimensional weight only to parcels larger than 1 cubic foot (1728 in³) on applicable Priority Mail zones. Smaller parcels are billed by actual weight.

Disclaimer

DIM weight is an estimate based on published divisors. Your real billable weight depends on your rate agreement, service type and surcharges (Large Package, Additional Handling). Verify against your carrier's rate card.

Divisors current for 2026 — carriers revise them periodically; verify against the latest rate card.

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