Knots per Square Inch, or KPI in Rugs
What do the KPI, or Knots per Square Inch, in Carpets and Rugs really mean
Learning about the KPSI or Knots Per Square Inch – The density of the knots in a rug or fineness of a pile rug is measured by multiplying the vertical knot count by the horizontal knot count within a given area measurement, either square inches or square decimeters.
Anything up to around seventy to eighty knots per square inch is considered coarse. As the number approaches 100 or exceeds it, the count enters the medium range.
When a rug begins to approach about 200 knots per inch, the weave begins to be considered as fine. The finely woven rugs may have as many as three or four hundred knots per inch, but such a count is considered to be exceptionally and even unusually fine.
To some extent the knot count depends on the size of the knots and the warps, i.e. the thickness and horizontal spacing of the yarns. But it also reflects how tightly the rows of knots and wefts are compacted vertically.