The quality of the carpet is directly correlated with the number of knots per unit area. However, the density can span from 25 to 1,000 knots per square inch (KPSI) or higher. Anything above 80 knots per square inch is deemed poor quality. At the same time, 120 to 330 KPSI is regarded as medium to sound quality, and anything above 330 KPSI is considered excellent quality.