This is the standard way of measuring wig length. The measurement is taken from the crown to the tips of the hair. This measurement is always given when the hair is straight.
This measurement is given to allow you to determine how long the wig will be on your body. It is taken from the hairline to the tips of the hair, going over the heads
The length of a wig is measured differently than extension hair, a wig is measured from the crown to the tips of the hair, whereas extensions are the same length all over the head, whether it's the crown or the nape. To have a wig the same length as your extension hair, please add 4 inches. For example, a 16 inch weave equates to a 20 inch wig.