As usual, you could order three bundles for your first sew in trial, that's typically number for your average sew in. With three bundles from 8 inch to 18 inch, this unit will be full, flowy, and glamorous. If your sew-in is starting with lengths over 20 inch, then you might want to consider 4 bundles with closure. The picture below for your reference.
The other factor is the size of your head (seriously), how full you would like your hair (yaki straight bundles styles generally have a lot of hair as an example), that means the textures affects how many bundles you need. Straight hair is usually less dense than curly hair, so you’ll need more bundles for a fuller look.
One more question, what is a closure(frontal)?
A closure hair is a hairpiece, usually made of lace or silk, lace is regular choice. The hairpiece is attached to a cornrow-base and secured with loose deep wave hair with closure around the perimeter to help protect you rown natural hair and be more natural-like.
If you are confused about closure,you can read this article All You Need To Know About Hair Closure-lace closure
Are 2 bundles enough for a sew in?
Yes if your bundles are 18 inches and below. The shorter, fuller, since all bundles weigh 3.5 oz.
How many bundles of hair is needed for a full sew in?
3 is recommended but this can range from 3 to 5 depending on your desired fullness.
How many bundles for a partial sew in?
2-3 is recommended, depends on the fullness
How many bundles of hair for a lace closure wig?
2-3 bundles and a closure(frontal) are standard but again it depends on fullness
Maybe you are clear already, or you could contact our on-line service for more.