Dimensional Weight Calculator: Dim Weight by Carrier Divisor
Calculate the dimensional weight of a parcel from its size and the carrier's divisor, compare it with the actual weight and see which one is billed. Enter length, width, height and the scale weight, pick UPS, USPS, air freight or express courier, or type your carrier's divisor, and get the cubic size, the dimensional weight, the billable weight and the difference, for up to 50 parcel sizes.
Your numbers
The carrier's published rule is the default: UPS rounds each side to the nearest inch and the result up; USPS rounds sides and result up; the metric sources state no rounding.
Up to 50 sizes. Measure the outside of the packed box at its longest points; use the scale weight of one packed parcel.
Billable weight
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- Dimensional weight
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- Actual weight
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- Billed above actual
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- Billed on
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- Cubic size
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- Rule applied
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Divisors and rounding rules as published by the carriers on 2026-10-13; the carrier's own rate quote decides. Surcharges for large packages are not included.
The calculation runs in your browser and ParrotNotes does not store your numbers. They sit in the page address so you can bookmark or share the result.
How to calculate dimensional weight
Measure the packed box on the outside at its longest points, multiply length × width × height for the cubic size, and divide by the carrier's divisor. The result is the dimensional weight. Compare it with the weight on the scale: the carrier bills whichever is greater, and that is the billable weight. The difference between the two is what the box's size, rather than its contents, is costing you.
Worked example at UPS's divisor of 139: a 20 × 16 × 12 inch box is 3,840 cubic inches; 3,840 ÷ 139 = 27.6, rounded up to 28 pounds. If the box weighs 10 pounds on the scale, it is billed at 28 pounds, 18 pounds above its actual weight. A 40-pound box of the same size is billed at 40 pounds, because actual weight is the greater figure. Add a row per box size for a multi-parcel shipment; the table under the result shows each size and the total.
Carrier divisors, as published
The presets above use the figures each carrier publishes, read on 2026-10-13. The divisor's units matter: 139 is cubic inches per pound; 5,000 and 6,000 are cubic centimeters per kilogram. The calculator converts your dimensions to the divisor's unit before dividing, so you can enter centimeters against UPS or inches against an express courier.
| Preset | Divisor | Applies to | Rounding, as published |
|---|---|---|---|
| UPS | ÷ 139 in³/lb | UPS domestic and international package services | Each side to the nearest whole inch; result up to the next whole pound |
| USPS | ÷ 139 in³/lb | Priority Mail Express, Priority Mail and Ground Advantage parcels over 1,728 in³ | Each side up to the next whole inch; result up to the next whole pound; 70-pound price above 70 lb |
| Air freight | ÷ 6,000 cm³/kg | IATA standard divisor for air cargo (Maersk) | None stated |
| Express courier | ÷ 5,000 cm³/kg | DHL Express (1 m³ = 200 kg) | None stated |
FedEx publishes its own divisor, but its pages could not be read on the day these figures were checked, so there is no FedEx preset: choose the custom divisor and type the figure from your FedEx rate guide. The same applies to regional carriers, consolidators and negotiated contracts, where the divisor is often higher than the list figure.
Why the rounding rule changes the answer
Carriers round before and after they divide, and the rules differ. UPS rounds each side to the nearest whole inch: 20.4 inches counts as 20, 16.5 counts as 17. USPS rounds every side up: 20.4 counts as 21. Both round the resulting weight up to the next whole pound. For a 20.4 × 16.5 × 12 inch box that is 4,080 cubic inches at UPS, billed as 30 pounds, and 21 × 17 × 12 = 4,284 cubic inches at USPS, billed as 31 pounds.
The rounding selector lets you apply a different rule than the preset's, for example when a rate card you hold states its own. The metric sources used here state no rounding, so those presets divide the exact cubic size; if your courier rounds up to the whole kilogram, choose that option.
Metric divisors: 5,000 and 6,000
In centimeters and kilograms the common divisors are 5,000 for express couriers (DHL Express publishes it: 1 cubic meter counts as 200 kilograms) and 6,000 for air freight, which Maersk describes as the IATA standard. A 60 × 40 × 40 cm carton is 96,000 cubic centimeters: 19.2 kg at 5,000 and 16 kg at 6,000. If it weighs 15 kg, the courier bills 19.2 kg and the airline 16 kg.
The inch and metric figures are the same factors expressed differently: UPS's air freight table lists 139 inches/pounds next to 5,000 centimeters/kilograms, and 166 next to 6,000. So a parcel priced at 139 in the US and at 5,000 in Europe is being measured by the same density.
How to lower a dimensional weight charge
Dimensional weight is a charge for air inside the box. The box that fits the product with the padding it needs, and nothing more, is the first fix; an inch off each side of the 20 × 16 × 12 box above takes it from 3,840 to 2,945 cubic inches and from 28 to 22 pounds at a divisor of 139. Check whether the box you ship in exists in a smaller standard size before ordering custom cartons.
For USPS, staying at or under one cubic foot keeps a light parcel on its actual weight. For dense goods, dim weight rarely applies, so splitting a mixed order into a heavy carton and a light one can cost more than one carton that is billed on actual weight. Run both layouts here before you decide.
Dim weight, freight class and CBM are three different numbers
Parcel carriers use dimensional weight. US LTL trucking uses the NMFC freight class, worked out from density in pounds per cubic foot: the Freight Class Calculator covers that. Ocean freight and most suppliers outside the US quote in cubic meters: the CBM Calculator does the cube, the volumetric weight for a whole shipment and the container fill. For how many cartons fit on a pallet, use the Pallet Calculator.
For reps who quote shipping
Distributor, packaging and wholesale reps hear the shipping question on the call: what will freight add to the order, and can it go parcel instead of pallet. Dim weight decides whether the light, bulky items in a catalogue ship for their weight or for their size, and which box size keeps them on the right side of that line.
The facts that set the quote come from the conversation: the pack size the buyer wants, how many per carton, whether the goods can be nested, who pays freight. Those move as the deal moves, and the quote has to match them.
Sources, each read on 2026-10-13. All results are estimates; the carrier's rate quote decides:
- UPS Rate and Service Guide, Daily Rates (as served on ups.com on 2026-10-13): cubic inches ÷ 139, sides to the nearest inch, result up; air freight factors 139/5,000 and 166/6,000
- USPS Domestic Mail Manual 123.1.3, Priority Mail: over 1,728 in³, sides rounded up, ÷ 139, result rounded up, 70-pound price above 70 lb
- USPS DMM 113.1.3, Priority Mail Express: the same rule
- USPS DMM 133.1.4, USPS Ground Advantage: the same rule
- DHL Express: volumetric weight = length × width × height in cm ÷ 5,000; 1 m³ = 200 kg; the higher weight is charged
- Maersk: the air cargo divisor of 6,000 is the IATA industry standard; the chargeable weight is the higher of actual and volumetric
More for distributor, packaging and wholesale reps: Distributor sales, Packaging sales, Wholesale sales rep, What is an RFQ.
The divisor is published. The deal terms are not.
Who pays freight, which box the goods ship in and when: those get agreed on the call, not in a rate table. Record the call in ParrotNotes and get a summary with the numbers and the action items, so the quote matches what was promised.
Get ParrotNotes freeRelated tools
- Freight Class CalculatorEnter a shipment's dimensions and weight to get its density in pounds per cubic foot and the density-based freight class it points to.Open the tool
- CBM CalculatorWork out the cubic meters of a shipment from carton sizes and counts, its volumetric weight, and how many cartons fit a 20 ft or 40 ft container.Open the tool
- Cubic Feet and CBM CalculatorWork out cubic feet and cubic meters (CBM) for boxes, pallets and rooms from inches, feet or centimeters, for one item or a whole shipment.Open the tool
- Pallet CalculatorWork out how many boxes fit on a pallet, per layer and in total, with the stack height, load weight and pallets for an order.Open the tool