Shipping rates are based either on the Actual Weight of the package or the Dimensional (Volumetric) Weight of the package and whichever is the larger of the two is adopted as the Billable Weight. We will illustrate with an example later on.

So what is Dimensional Weight?  Dimensional Weight is the shipping rate based on the package size or amount of space in cubic centimeters (Cubic inches) or Package Density that a package occupies in relation to its actual weight.

Space is important to courier or logistic companies as delivering more packages translates to higher earnings. As an example, a pair of ladies boots will weigh more than a pillow for adult use, however, the shipping rate of the pillow will be higher than the rate for the boots because it has a higher dimensional weight, in order words, it occupies more space.

Space in a truck or plane is not infinite, so maximizing space equals maximizing earnings by not losing money on lightweight but space consuming packages. That is why carriers see the need to charge by dimensional (Dim) weight.

How to Calculate Dimensional Weight based Rate

  • Dimensional Weight = (Length x Height x Width) / DIM factor


The DIM factor is a constant number considered as the base weight of one cubic centimeter (cubic foot) of space and is specific to each carrier.  For all the major carriers the domestic DIM factor differs from the International Dim factor.

What is of our concern here is the International dim factor which is 5000 cm3/kg or 139 in3/lb , so the higher  the Dim factor the lower the dimensional weight and vice versa.

How to calculate Dimensional Weight based Rate

  1. Calculate the volume of the package in cm or (in)


Length x Height x Width

  1. Dimensional Weight is equal to Volume divided by Dim Factor


Dimensional Weight kg (lb) = (Length x Height x Width) / DIM factor


  1. Determine the Billable Weight


Compare the actual weight of the package with the Dimensional Weight and the greater of the two is the Billable Weight.

Let’s find out using the pillow as an example

Actual Weight of pillow package is 3kg

Dimension of pillow package Length: 50cm, Width: 20cm, Height: 35cm

Dim Weight = 50 x 20 x 35 = 35,000 cm3

= 35,000 / 5000 = 7 kg

In this example the dimensional weight (7kg) is bigger than the Actual weight (3kg) so Dimensional weight is adopted as Billable Weight. Let’s convert to monetary terms to see the impact.

if the courier charges US $3 /kg

In Actual Weight terms the shipping rate is 3kg x3 = US $9

In Dim Weight terms the shipping rate is 7kg x3 = US $21

As you can see from the example, you will be paying more with Dim weight that with the actual weight for lightweight but space consuming packages, the difference is so marked it cannot be ignored. Thus, the key to reducing shipping rate of lightweight/bigger volume packages is to minimize the size of the package as much as possible.

MyJapanAddress has already put in place measures to optimize packaging. The measures listed below have led to significant savings that is reflected in our low shipping rates.

  1. Utilizing packaging space effectively by packing as tightly as possible without sacrificing safety.
  2. Use of packing materials that don’t bulge or expand
  3. Having in stock a wide variety of package sizes.
  4. Adoption of light package fill-ins