To calculate the girth of a package, follow these guidelines:

Measure the three parcel dimensions in inches:
Example: 50 inches (Length) x 40 inches (Width) x 30 inches (Height).

Add the measurements of the two smallest dimensions together. Multiply the result by two. This is the girth of your package.
Example: 40 inches (Width) + 30 inches (Height) = 70 inches. 70 inches x 2 = 140 inches (Girth).

Now simply take the longest dimension and add this to the package girth. The result is the combined length and girth of your parcel.
Example: 50 inches (Length) + 140 inches (Girth) = 190 inches (Combined Length and Girth)