What is the Norwood Scale?
Often referred to simply as “NW”, the Norwood Scale refers to a hair loss measurement system that charts the progressive stages of male pattern hair loss (MPH). It is officially known at the "Norwood Hamilton" scale because Dr. James Hamilton originally designed this chart in the 1950s but it was Dr. O’tar Norwood in 1975 that made the final modifications to the chart for classifying hair loss in males. Although this scale is widely inaccurate and incomplete, it has since become the standard in which all hair restoration clinics use to classify their patients.
What is the Purpose of the Norwood Scale?
Even though it is not fully accurate, the Norwood Scale is employed throughout the world for two reasons:
- This scale gives a visual tool for patients and doctors to use when describing male pattern hair loss (MPH). From the doctor’s perspective, it is a way to demonstrate to the patient what they can potentially expect to happen next. For the patient, this scale is an easy way to describe their MPH over the phone and during initial consultations.
- When studying MPH, the Norwood Scale gives researchers a basic set of like terms to use. It is also easier to describe the earlier and later stages of hair loss using the NW numerological phrasing. All in all, the NW terminology helps minimize confusion.
How does the Norwood Scale Work?
The scale works by showing pictorial depictions of Norwood’s seven levels of hair loss. They are:
- NW1 – no hair loss and no recession. The scalp is fully covered by healthy hair.
- NW2 – a minimal amount of recession in the temple areas. Sometimes referred to as "the corners", the temples recede normally on many men as they transition from a juvenile to an adult.
- NW2a - In addition to mild temple recession the frontal hairline has receded as well.
- NW3 – recession in this stage is considered moderate but can be very devastating for some sufferers, and a moderate concern for others. Typically, the temple area has recessed a few centimeters. No thinning occurs anywhere else on the scalp.
- NW3 Vertex – a sublevel of NW3 that refers to a more aggressive amount of thinning near the vertex and crown areas, but not heavy enough to qualify as NW4.
- NW4 – at this point, what was initially anterior hair loss now encroaches upon the back area. The vertex and crown have noticeably thinned or show bare patches as well.
- NW4a - This is complete frontal recession and temple recession with the mid-scalp remaining intact and no or little thinning in the crown.
- NW5 – only a small strip of hair separates the mid-scalp from the crown. The rest of the scalp is typically visible.
- NW5a - Progression from a NW4a with loss extending past the mid-scalp and halting at the vertex, leaving the crown mostly intact.
- NW6 – the strip of hair separating the mid-scalp from the crown vanishes. Hair still may stand tall around the temple area, however.
- NW7 – this is the final stage of hair loss according to the Norwood Scale. At this point, only a horseshoe-shaped patch of hair wraps around the back of the scalp. The top of the scalp is most likely completely bald.
These classifications do not require full and total hair loss in the designated areas as obvious thinning can be interpreted as loss. In many cases a doctor will add "diffused" to the classification to relay additional information about the type of loss, stipulating that complete loss has not occurred but rather the patient is simply thinning in the pattern stated.
Who can Use the Norwood Scale?
Anybody is eligible for the Norwood Scale, regardless of gender. The only requirement is that they are experiencing MPH, and not female pattern hair loss (FPH), or any other form of alopecia. With FPH, there are two separate measuring systems known as the Savin and Ludwig scales. While uncommon it is not considered to be unusual for woman to be affected by MPH that results in one of the classifications on the Norwood scale.