The Hamilton-Norwood classification system
The Hamilton-Norwood classification system is used by hair restoration specialists to gauge the extent and progression of male pattern baldness, also known as androgenic alopecia. This classification system was developed in 1951 by Dr. James B. Hamilton and modified by Dr. O'Tar Norwood in 1975. Also commonly referred to as the Norwood classification, it is the tool most widely used by hair restoration specialists to assess hair loss patterns and plan for hair restoration treatment.
Hamilton-Norwood has seven classifications
The higher your personal hair loss situation is on the Norwood scale, the more grafts and hair restoration sessions may be required. In most cases, the primary areas of hair loss are the crown and V-patterns in the front temporal area--either side of and above the forehead moving toward the crown. The following descriptions of the seven Norwood classifications are from the Bernstein Medical Center for Hair Restoration website:
- Norwood I: Normal head of hair with no hair loss
- Norwood II: Hair receding slightly in V-shaped pattern in front temporal area (does not represent balding)
- Norwood III: Earliest indication of balding; hair receding further into the frontal temporal area
Norwood IIIv: hair loss in the crown or vertex - Norwood IV: Additional hair loss in the temporal area; more loss from the crown; solid line of hair still visible between the two areas
- Norwood V: Increased hair loss in front temporal area and crown; line of hair between two areas decreases
- Norwood VI: Line of hair between front temporal area and crown disappears
- Norwood VII: Extensive hair loss with remaining hair only on back and sides
Three Norwood sub-classifications define a slightly different pattern of baldness. Norwood classifications IIa, IIIa, IVa, and Va describe the progression of hair loss from front to back, with limited hair loss in the crown, and without the hair bridge characterized by the primary Norwood classifications.
