You can count the knots, although knots don’t count!

Posted: April 08, 2012

Knots Alone Don’t Count

The facts pertaining to the knot count of an Oriental rug are a little complicated. Just counting the knots per square inch (kpsi) alone normally does not give a true indication of the quality of an Oriental rug. One also needs to know the type, and the village or the tribe that the rug comes from. Each country of origin has a traditional knot count specific to that area. For example, a medium knot count of 200 kpsi might be the finest example of weaving from a particular nomadic tribe. In turn, a high knot count of 6000 kpsi for a fine city rug may not necessarily be the finest for that area, as the finest rug from the area may normally be 9000 kpsi. Therefore, purely counting knots without knowing the type and origin of the rug is not a good indication of it’s quality or value.

The Parts of a Rug

The parts of an Oriental rug are:

  • The warp threads run lengthwise and make up the fringes of a rug.
  • The weft threads run across the width of the rug.
  • The selvage or edge of the rug is made by wrapping several warps at the edge of the rug with yarn to reinforce this part of the rug.
  • The knots which are tied to the warps create the pile or nap of the rug.

The warp and weft threads make up the foundation of the rug and cotton is generally used. In a hand made rug, the knots which are tied around the warp threads and make up the “pile” of a rug, can be made of wool or silk or both.

Labor Intensive

Since the knots in a rug are tied by hand and since a weaver can tie approximately 8000 knots per day, the number of knots per square inch (kpsi) times the number of square inches gives some approximation of the labor content. It can literally take 9-12 months to produce one 9′ x 12′ hand knotted Oriental rug!

Typically, the pattern and colors are what makes a rug attractive to the beholder! And since the joy of an Oriental rug is the pattern, the complexity of the pattern and the execution of the weave, these complexities make it difficult to compare similar knots per square inch from the different countries, villages or nomadic tribes. In addition, each country and tribe has a different method for defining their basis for knot counts. There are also many knot constructions used by each country or tribe. Below is a VERY brief definition and comparison chart for a few major rugs producing countries.


India developed a quality rating system that we have listed below. Two numbers are used as such; 9/9. The first number is the number of knots in 9/10 of an inch of the rugs width. The second figure is the number of knots in 4 1/2 inches of the rugs length. This is the conversion chart to knots per square inch (KPSI).

Quality   KPSI (knots per square inch)

3.5/32      28
5/28         35
5/32         40
6/6           36
6/40         59
6/45         67
7/18         31
7/40         69
8/8           64
8/36         71
9/9           81
9/25         56
9/54         120
9/60         133
10/10       100
10/14       140
10/32       79
10.5/48    124
11/32       87
12/60       178
13/65       209
14/14       196
16/80       316


A ruler of 12 inches is used to count the number of pairs of warps in one linear foot. Since the construction is square, you multiply the number of pairs of warps or the “line” count by itself and divide by 144 for the number of knots per square inch. For example 120 line is 120 x120 then divided by 144 or 100 knots per inch.

Line    KPSI

50          17

60          25

70          34

80          44

90          56

100        69

110        84

120        100

130        117

150        156

160        180

200        278

300        625

Iran: (Persian)

Persian rugs are based on a unit of measure called “raj” or about 7 cm. Most, but not all, of the best rugs have a square knot construction or the same number of knots in both width and length. Below is a basic chart converting raj to knots per square inch.

Raj     KPSI

30      118

40      210

50      329

60      473

70      675

90      1066

Mark Gonsenhauser is a foremost expert on Oriental rugs and specializes in selling one-of-a-kind hand knotted and woven rugs from around the world as well as quality machine made rugs. Come by our Virginia Beach rug and carpet store and see our vast selection of rugs.