Guidebook

1. What is hair density

Hair density refers to the number of hair strands growing per square inch of your scalp. Typically, we have 80,000 to 120,000 hairs on the scalp, and hair density is generally at its highest around the hair vertex (crown). There is no clear definition of good or bad as hair density being too high or too low, but one study in 2018 did identify that Caucasian descent has highest density when compared with Hispanic and African descents. Although hair density level is mainly determined by genes, other factors can also affect your hair density, such as age, nutrition deficiency and stress levels. For hair stylists, knowing the hair density levels is necessary to cut hair and to apply the right hair styling products. Meanwhile, monitoring hair density also helps dermatologists to determine if you are suffering from hair loss problems.

To assist diagnosis of hair density, up to 5 images can be taken under the XPL light using the Chowis Hair Analyzer. Our company algorithm then evaluates the hair density for each image and provides the final hair density level.

2. Chowis hair density grade

The following Chowis hair density grade has been co-developed by Chowis and dermatology experts. To obtain the hair density grade, we first detect hair and calculate hair density to provide a quantified result score for each image. Then we compute the final score for hair density as the average of all result scores. Finally, we grade hair density as clear, almost clear, mild, moderate and severe based on the scale shown in Table 1.

Table 1. Hair denstity grade
Grade	Scale	Description
Clear	91 ~ 99	The person has hair thicker than average
Almost Clear	75 ~ 90	Good hair density: no need to be concerned about hair loss
Mild	50 ~ 74	Normal hair density
Moderate	25 ~ 49	Low hair density: starting to notice hair thinning
Severe	0 ~ 24	Very low hair density: suffering from severe hair loss

Table 2. Representative images of hair density grade
Clear
Almost Clear
Mild
Moderate
Severe