In short, carpet density is measured by how close each carpet fiber is tufted into the carpet backing. It is also important to note that carpet density and face weight are not the same and should not be used interchangeably. Additionally, carpet face weight and carpet pile height are both needed to calculate the carpet density.
Carpet face weight is defined as the weight in ounces of carpet fiber found in one square yard. On average, carpet face weight ranges from 20 ounces to 100 ounces.
Carpet pile height is the length of the carpet fibers, starting from where they attach to the carpet backing to the end tips of the fibers.
Pile height reference:
To find out the carpet density, take the carpet face weight and multiply it by 36. Then you will divide that number by the pile height of your carpet. After those two calculations, you will get the density of your carpet measured in ounces.
For example, if a carpet has a 40-ounce face weight and a pile height of half an inch, it would have a density of 2,880 ounces per cubic yard.
(40 x 36 / 0.5 = 2,880)
Carpet density is also greatly influenced by its gauge, which is how far apart the yarns are in a carpet across width. The higher the number, the denser the carpet. An 1/8 gauge carpet has 8 tufts per inch or 64 tufts per square inch while a 1/10 gauge carpet has 10 tufts per inch or 100 tufts per square inch.
When shopping for a new carpet, carpet density should be one of the factors you consider related to quality. It is important to note that one factor alone will not give you a good indication of carpet quality. It would be best to consider various factors, including carpet density, fiber type, face weight, and backing material. The only time you can rely on carpet density alone is if all the other factors are equal. In that case, a carpet with a higher carpet density would be considered a better-quality carpet, and it will feel thicker and lusher as you walk on it.
For typical household carpets, a carpet density value of 3,000 or higher is standard. A value lower than this number should cause pause and might indicate that you should consider a different carpet for your home.