How many ounces of hair do I need for a full sew in?

While everyone’s hair is slightly different, we have provided the following list to help you determine roughly how much hair you will need for a weave: Full head sew in weave: Hair 10″ to 16″ long. 4 ounces = A half head of extensions (to add body or length) 8 ounces = A full head of extensions.