The twist of a carpet is defined as the number of times the fibers are turned (or twisted) in a one-inch length, represented by a number. For example, strands that are twisted 6 times in a one-inch length have a twist number of 6. This number is sometimes referred to as the TPI—turns per inch. This referred to as carpet twist, yarn twist, turns or Turns Per Inch (TPI).
Why is Twist Important?
The twist number is a very good indicator of carpet quality. The higher the twist number (i.e., the more the carpet strands have been twisted), the better the performance of the carpet. Twisting the fibers together increases their strength, resulting in a carpet that will be more able to withstand traffic and resist crushing. Long fibers that have a high twist, such as friezes, are very durable.
Fiber twist is a factor only in cut pile carpets. Looped styles (Berbers) are not gauged by twist because the yarns are looped back into the carpet.
Most residential cut pile carpets have a twist number of between 3 and 6, while some friezes have up to 8 turns per inch.
Not all manufacturers indicate the twist number of a carpet on their labeling. Luckily, though, it is something that is relatively easy to determine on your own simply by examining the carpet up close. Isolate a strand of fibers, measure a one-inch length, and count the number of twists in it. If the carpet pile is less than one inch, measure half an inch and double the number to determine the twist number.
While the twist is an important factor in determining the overall performance of a carpet, it is not the only consideration. All factors must be regarded together to form the whole picture of a carpet's quality.