How do I calculate dimensional weight?

How do I calculate dimensional weight of a package?

Dimensional-weight pricing is applicable on a per-package basis to all shipments in customer packaging. FedEx packaging may also be subject to dimensional-weight pricing. Dimensional weight is calculated by multiplying length by width by height of your package (in centimeters) and dividing by 5,000 (standard density in cubic centimeters per kg). Alternatively, if the dimensions are in inches, the divisible is 305 (standard density in cubic inches per kg) or 139 (standard density in cubic inches per pound).

Dimensional weight (kg) =	Length x Width x Height (centimeters or inches) ^{_____________________________________________________________}
Dimensional weight (kg) =	5000 for centimeters or 305 for inches

	Dimensional weight (pound) =	Length x Width x Height (inches) ^{__________________________________________}
139 for inches	Dimensional weight (pound) =