The most common measurement used in classifying the level of hair loss in men is the Norwood Scale (or Hamilton-Norwood Scale). The Norwood measurement system ranges from a level one, which represents little to no hair loss, to a level 7, which is characterized by severe baldness where only a rim of hair remains.
The hairline shows minimal or no recession. Men at this stage should monitor their hair regularly for any signs of thinning.
The frontal and temporal regions start to show recession, typically in symmetrical triangular shapes. The initial signs of hair loss are becoming more visible.
This level of hair loss is considered “cosmetically significant”. The symmetrical hair loss at the temples is more pronounced and these areas may be bare or sparsely covered with hair. At this stage, the hair also begins to thin at the crown.
Hair loss in the frontal and temporal regions is more severe than in Type III. Additional thinning is visible in the front central region and thinning at the crown becomes more pronounced. A moderately thin band of hair usually separates the two areas of hair loss.
At this stage, there is still a separation between hair loss at the crown and hair loss in the front and temporal regions. However, the dividing area is becoming narrower. A “horseshoe” shape pattern of remaining hair is beginning to form.
More severe hair loss is clearly visible as the hair separating the crown and hairline areas is nearly gone, with only sparse hair remaining.
This is the most severe form of hair loss. There is a complete loss of hair in the front, temporal and crown regions. The horseshoe pattern of hair at the back and sides of the head is all that remains and it may be thinner or less dense than it was previously.