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Dimensional Weight Calculator

Find a parcel's dimensional (volumetric) weight from its size and a carrier divisor, and the billable weight a shipper would charge you for.

Level: Grades 5–6

  • Common Core standard 5.MD.C.5.bApply the formulas V = l × w × h and V = b × h for rectangular prisms to find volumes of right rectangular prisms with whole-number edge lengths in the context of solving real world and mathematical problems.
Printable worksheet

Dimensional Weight Calculator

Know the answer you need? Pick an input to work backward.

Inputs
Units

Result

Billable weight

22 lb

A 18 × 14 × 12 in package has a dimensional weight of 21.76 lb; it is billed at 22 lb.

Dimensional weight
21.76 lb
Actual weight
15 lb
Billed on
Dimensional weight
Package volume
3,024 in³
Volume in cubic feet
1.75 ft³

See the step-by-step solution ↓

Step-by-step solution

  1. Find the package's volume: length × width × height

    18×14×12=3,024 in³

  2. Find the dimensional weight: divide the volume by the carrier's divisor, the space it counts as one unit of weight

    3,024139=21.755396 lb

  3. Round both weights up to the next whole pound, the way carriers bill

    dimensional 22 lb, actual 15 lb

  4. The carrier charges for whichever is greater, the dimensional or the actual weight. That's the billable weight

    max(22, 15) = 22 lb

Test yourself

20 quick questions built from this calculator's formula: work out results, predict what happens when an input changes, and work backward from an answer. Every answer comes with the working.

Please note: Results are estimates for planning and comparison. Lenders, banks, and tax authorities may round differently or include fees not modeled here, so confirm figures with your provider before deciding.

What this calculator does

Find out what weight a carrier will actually charge you for when you ship a box. Parcel carriers charge for the space a package takes up, not just how heavy it is. A large box of pillows weighs little, but it fills a truck just as much as a box of books.

To account for that, carriers turn a package's volume into a dimensional weight, also called volumetric weight. Then they charge on whichever is greater: the dimensional weight or the actual weight. That greater figure is the billable weight.

This calculator finds the volume and divides it by the dimensional divisor. It rounds the weights the way carriers usually do and tells you which weight sets the price. The usual divisors are 139 for inches and pounds and 5000 for centimeters and kilograms. But carriers and service levels vary, so you can change the divisor.

Where it's used

Why this math matters outside the classroom:

  • Shipping a box. A 20 × 16 × 12 inch box has a volume of 3,840 cubic inches, which is about 27.6 pounds at a divisor of 139.
  • Billable weight. If that box actually weighs 10 pounds, the carrier bills the larger dimensional weight instead.
  • Choosing box sizes. Online sellers compare a few box sizes to find one that keeps the dimensional weight close to the actual weight.
  • Warehouse packing. Packers measure length, width and height in whole inches and multiply them before dividing by the carrier's divisor.

Grade level and standards: Grades 5–6; Common Core State Standards for Mathematics 5.MD.C.5.b. © Copyright 2010. National Governors Association Center for Best Practices and Council of Chief State School Officers. All rights reserved.

How to use it

  1. Pick inches and pounds or centimeters and kilograms.
  2. Enter the package's length, width and height. Measure at the widest points, including any bulges.
  3. Enter the actual weight, and check that the divisor matches your carrier's rate.
  4. Choose the rounding rule. Then read the billable weight and whether it comes from size or weight.

What the inputs mean

Length
Measure the longest side. Many carriers round each measurement to the nearest whole inch or centimeter before calculating. If yours does, enter the rounded figures.
Dimensional divisor
Cubic inches per pound. 139 is the most common figure for domestic and international parcel services. Some services use 166 or another value. A larger divisor gives a lower dimensional weight.
Round weights up to
Carriers usually round billable weight up to the next whole pound or kilogram. Some metric services round to the next half kilogram.

Formula and method

volume = length × width × height
dimensional weight = volume ÷ divisor
billable weight = greater of (dimensional weight, actual weight), after rounding up

The divisor is how dense the carrier assumes a box is. With 139 in³/lb, the carrier treats every 139 cubic inches of box as at least one pound. A box lighter than that pays for its size. A heavier one pays for its weight.

With 5000 cm³/kg, the assumed density is 200 kg per cubic meter (1,000,000 ÷ 5000). The US figure of 139 in³/lb works out to about 199 kg per cubic meter. So the two common divisors describe almost the same density.

Both weights are rounded up before they're compared. So a dimensional weight of 21.1 lb is billed as 22 lb under whole-pound rounding.

Worked example

A box measures 18 × 14 × 12 inches and weighs 15 pounds. The carrier uses a divisor of 139 and rounds up to the next pound.

  1. Volume: 18 × 14 × 12 = 3,024 cubic inches (1.75 cubic feet).
  2. Dimensional weight: 3,024 ÷ 139 = 21.76 lb.
  3. Round up: dimensional 22 lb, actual 15 lb.
  4. Billable weight: the greater of 22 and 15 is 22 lb.

Result: The box is billed at 22 lb on its dimensional weight, 7 lb more than it actually weighs. In metric, a 45 × 35 × 30 cm box weighing 7 kg has a dimensional weight of 47,250 ÷ 5000 = 9.45 kg and is billed at 10 kg.

Understanding the result

If the result says 'Dimensional weight', a smaller box would lower the cost. Trimming even an inch from each side can drop the billable weight by several pounds.

If it says 'Actual weight', the box is already dense enough that its size doesn't affect the price.

Use the billable weight with your carrier's rate table. This calculator doesn't price the shipment.

Assumptions and limitations

  • The package is a rectangular box. Odd-shaped items are measured by the smallest box they'd fit in.
  • The same divisor and rounding apply to both weights.
  • The measurements you enter are already rounded the way your carrier requires.
  • Carrier rules change and differ by service, so confirm the divisor and rounding with your carrier.
  • Extra fees for oversized, heavy or non-standard packages aren't included.
  • Freight pallets and air cargo may use different density rules.

Frequently asked questions

Why is my shipping charge based on more than the box weighs?

Because the dimensional weight is higher than the actual weight. Carriers price by the space a parcel takes as well as its weight. They charge for whichever is greater.

Should I use 139 or 166?

Use whatever your carrier's current rate guide says for your service. 139 is the common figure for many parcel services today. 166 has been used for some retail and postal rates. The higher the divisor, the lower the dimensional weight.

How can I reduce dimensional weight?

Use the smallest box that protects the item, and don't overdo the packing fill. Think about poly mailers (plastic shipping bags) for soft goods. Volume multiplies three measurements together, so small cuts on each side add up quickly.

Is volumetric weight the same as dimensional weight?

Yes. Volumetric weight is the more common term with metric units and international shipping. Dimensional weight, or dim weight, is more common in the US. The calculation is the same.

How this calculator is checked

Method: Carrier dimensional weight method: L × W × H ÷ divisor, with billable weight as the greater of dimensional and actual weight. The calculation is covered by automated tests with known reference values and edge cases. Last updated 2026-10-18. Found a problem? Tell us.

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