Article in English: Use a ruler or tape measure to find the dimensions of the package’s longest side, shortest side, and standing sides. Round each of your measurements off to the nearest whole inch and write them down on a piece of paper.  When calculating the dimensional weight of a package, it doesn't matter which measurement corresponds to which side—all that matters is that all of your measurements are as accurate as possible.  Note that dimensional weight calculations can only be used with imperial units of measurement. They will not work for metric measurements. (To use the formulas below with the metric system, replace 166 with 5000.) Cubic size is essentially the same thing as volume, which indicates the amount of space inside the box. If you have a package with a length of 12 inches (30 cm), a width of 8 inches (20 cm), and a height of 4 inches (10 cm), it’s total cubic size would be 384 inches (980 cm). Some shipping services may use the term “volume” in place of “cubic size.” Shipping costs differ based not only on a package’s size, but its destination. For shipments being sent within the U.S or Puerto Rico, divide the cubic size of your package by 166. For international shipments, divide the cubic size by 139.  Going off the cubic size calculated in the previous example, the dimensional weight would be 2.31 for domestic handling and 2.76 for international shipments.  Don’t round your dimensional weight. It needs to be exact in order to properly tab up your shipping costs. Place your package on the scale and wait for it to display a reading. Be sure to record the weight accurately, as you’ll be checking it against the package’s dimensional weight to see how much you can expect to pay for shipping. You can request to have your package measured at the post office if you don’t own a postage scale. If the dimensional weight is greater than the actual weight, it will be designated as the “billable weight,” or the weight you’re being charged to ship. Most shipping services set the larger of the two measurements as the...

Summary in Chinese:
测量包裹的长宽高。 将箱子的长宽高相乘，算出立方尺寸。 将立方尺寸除以正确的除数，就能得出体积重量。 用邮资秤称出包裹的准确重量。 将包裹的实际重量与体积重量进行比较。