An old myth within the rug evaluation world was that the "knots per square inch" would determine the value of a handmade rug. As a general rule, many of the rug districts that loomed the tightest knotted rugs were regions that made the same design with the same colors one after another. Every loom in the region would in essence be knotting identical rugs in various sizes. Therefore, because of the lack of innovation, and the incredibly low wages, this was often an inaccurate yardstick.

The quality of the wool, the quality of the dyes and the flow of colors and design often is a more accurate judge of a rug's value. Because of American fashion trends, rugs from some regions have become more sought after, therefore they have grown more scarce. The ensuing shortage has raised prices for rugs from these regions.

Another factor in determining value and price is that in many regions the majority of the looms were the same width creating size voids. Price and value here are determined by lack of supply. For example, an antique 5' x 8' is quite difficult to find, therefore, the price per square foot would be higher than a more commonly loomed size.

In summation, the artistic design and coloration and scarcity of product often determines the value of a rug more so than the density of knots in a rug.