The hair normally stands on end when cut and styled into a crew cut. However, the classic crew cut has a slightly stricter definition, so it is important that barbers be familiar with how to give a crew cut.
Crew cut hairstyle
The classic crew cut is a sort of a fade that starts out with the sides and back of the hair cut very short, typically about 1/8 inch. At the crown of the head and forward, the length is allowed to slowly taper to a longer length as one moves toward the front of the head, usually less than 1/2 inch. The hair is then trained to stand straight up if it does not do so on its own.
If the crew cut is done properly, the top of the head will look like a landing strip. One variation on the classic crew cut is the flat top. This is accomplished by cutting the hair on top of the head shorter and tapering the length to longer as one moves away from the top so that one can lay a ruler or other straight edge on top of the head and have hair touching it all the way around the top of the head.
There are other variations on the crew cut that are more popular in different areas and among people with different occupations. The common thread that ties them together is that all a short hairstyles and all have tapered hair lengths so that part of the hair is slightly longer than the sides and back.