How Many Bundles do I need for a Full Sew-in?
"To achieve a natural look, you will need 2 bundles of hair extensions for lengths between 12 and 16 inches, depending on the size of your head. For lengths between 18 and 22 inches, you will need 3 or more bundles, again depending on the circumference of your head. If you want hair that is 24 inches or longer, you will need at least 4 bundles. If you desire a fuller look, you will need more bundles than these recommended amounts."
