The Norwood scale (or Hamilton-Norwood scale) is the leading classification system used to measure the extent of male pattern baldness. Men typically lose their hair in one of several common patterns over many decades. The Norwood scale provides easy-to-reference images that indicate different stages of balding.
There are several other classification scales used by doctors, researchers, and hair transplant surgeons. Some classification scales include both sexes or focus on female pattern baldness.
The Norwood scale, however, is the measurement that’s most commonly used by clinicians when discussing male pattern baldness. It provides a reference point to diagnose the extent of baldness, discuss treatment options, and measure the effectiveness of treatment.
What are the 7 stages of hair loss?
The Norwood scale has seven stages. Each stage measures the severity and pattern of hair loss.
- Stage 1. No significant hair loss or recession of the hairline.
- Stage 2. There is a slight recession of the hairline around the temples. This is also known as an adult or mature hairline.
- Stage 3. The first signs of clinically significant balding appear. The hairline becomes deeply recessed at both temples, resembling an M, U, or V shape. The recessed spots are completely bare or sparsely covered in hair.
- Stage 3 vertex. The hairline stays at stage 2, but there is significant hair loss on the top of the scalp (the vertex).
- Stage 4. The hairline recession is more severe than in stage 2, and there is sparse hair or no hair on the vertex. The two areas of hair loss are separated by a band of hair that connects to the hair remaining on the sides of the scalp.
- Stage 5. The two areas of hair loss are larger than in stage 4. They are still separated, but the band of hair between them is narrower and sparser.
- Stage 6. The balding areas at the temples join with the balding area at the vertex. The band of hair across the top of the head is gone or sparse.
- Stage 7. The most severe stage of hair loss, only a band of hair going around the sides of the head remains. This hair is usually not dense and may be fine.