Perm and Hair Shrinkage

Long hair with perm curls
Photo: Pathdoc/Shutterstock
Q: If you get a perm. How much does your hair shrink up?
A: This is a good question. Not many people realize that a perm changes the hair's apparent length. They imagine that if their hair is shoulder length normally, that they can get it permed into a curly style and it will still be shoulder length, only curlier. They get a rather rude shock when they discover that the hair that was brushing their shoulders before the perm, now hangs inches above the shoulders.
The amount of “shrinkage” caused by adding curl depends on a few factors: the length of the hair being permed, the firmness of the curl created, and the size of the curl. The longer the hair is the heavier it is, and this weight will “stretch” the curl, preventing it from being as tight as it would get if the hair were shorter. (This is why many women with naturally curly hair find themselves with hair that looks shorter than intended when they get their hair cut.)
The firmness of the curl created is also referred to as the “strength” of the curl. There are different perm formulas that offer differing firmnesses (or strengths) of curl. Some women prefer a tight coiling curl, while others want simple soft waves. A stronger curl is needed with longer hair to actually achieve a “curly look” instead of simple “waves” because of the weight of the longer hair. Shorter hair (or fine hair) can use a less firm curl because the hair is light enough that the curls hold their shape with even the softest curl.
The size of the curl is also a factor because larger curls tend to be softer and looser, while tighter curls tend to be firmer. This is apparent in the use of very large wrapping tools – or perm rods – for creating body waves as opposed to using smaller rods for more curl. The designations of “smaller” and “larger” rods are relative to the length of the hair being permed and the number of times the hair shaft winds around the rod when the hair is wrapped for a perm.
Generally, you can expect to lose 25-30% of the hair’s apparent length in an average perm. This percentage can vary depending on the factors above and the styling methods used after perming. However, rather than think of it as lost length, think of it as being converted into “volume”. The length is still there, it is simply resting in a different position in the hairstyle.
See also:
How much will hair stretch?
How long does hair have to be to get a body wave?
Do you know how much your hair is lifted when you get a perm?