The Army regulation for haircuts differs for men and women. For men, their hair must present a tapered appearance and the hair will not fall over the ears or the eyebrows. The hair will also not touch the collar except for where it is closely shaved at the base. Side burns will be nicely trimmed and not exceed below the the lowest part of the exterior ear opening. For females, they will ensure their hair is neatly groomed, and does not present a ragged or unkempt appearance. Hair will not fall over the eyebrows or extend below the bottom edge of the collar at any time during normal activity. You can also find more army grooming standards in AR-670-1.