The Hamilton-Norwood Scale, better known simply as the Norwood Scale, is a way of measuring and categorizing male pattern baldness using an illustrated representation of the progression of hair loss in men. The scale ranges from stages I to VII. A hair restoration doctor or clinician will refer to a patient as, for example, a “Norwood 4A”
The measurement scale was first conceived by Dr. James Hamilton in the 1950s. It was later revised and updated by Dr. O’Tar Norwood in the 1970s. It is widely used among hair restoration professionals throughout the USA, Canada, Britain, and to some extent globally.
It is quite useful in its simplicity, such that a layperson is generally able to determine that his hair loss was at, say, a 3A two years ago, but has progressed nearer to a 3V recently.
More advanced, accurate methods of measuring hair loss include the patented Hair Check, a device that measures the area of a bundle of hair in a specific scalp area and provides a number, the Hair Mass Index (HMI), that can be compared from one year to the next.
If you would like to know exactly where you are on the scale, download the ARTAS® Hair App from Restoration Robotics, take photos of your head with your iPhone, and upload them directly to Dr. Harris at RESTORE.
A similar chart exists for female pattern baldness, known as the Ludwig Scale.