The knotting density is an important indicator of the effort of a handmade carpet. It is measured per square metre and also provides information on the fineness and durability of a carpet. Very coarse carpets start at around 50,000 knots per square metre, while the finest carpets, such as Tabriz 70Raj, have a knot density of well over 1,000,000 knots per square metre. Such pieces are made by highly experienced master knotters and are also interesting for collectors. The knot density of a carpet can be quickly estimated with the help of its reverse side. The number of knots is multiplied by one hundred over a length of one centimetre and then squared. The result is the approximate knot density per square meter. It should not be forgotten, however, that the number of knots can vary with knots running up and sideways and is not always the same across the carpet surface.
The knotting of a rug is based on centuries of tradition. Thus, different knotting techniques have been developed across the different regions. Basically, four different knot types can be distinguished. The symmetrical Knot is robust and originates from the Turkish area. The asymmetrical knot allows denser knotting and is also called a Persian knot. There are also Jufti and Tibetan knots, but these are now called less widespread.
