What Is Raj? Persian Rug Knot Density Explained
Raj is the most common measure of fineness for Persian handwoven rugs. This guide explains how raj is counted, how it converts to knot counts, and how much weight to give it when choosing a rug.
What raj means
Raj (رج) is the number of knots across 7 cm of the rug's width. To count it, turn the rug over and count the knots in one horizontal row over a 7 cm length.
Converting raj to knots
If the knot density is the same in both directions, knots per square metre are roughly (raj ÷ 0.07)², or about raj² × 204. Divide by 1,550 to get knots per square inch (KPSI).
| Raj | Knots per m² (approx.) | Knots per sq. inch (KPSI) | Typical use |
|---|---|---|---|
| 30 | 184,000 | 119 | Village and tribal rugs |
| 40 | 327,000 | 211 | Good city rugs |
| 50 | 510,000 | 329 | Fine rugs with silk highlights |
| 60 | 735,000 | 474 | Very fine weaving |
| 70 | 1,000,000 | 645 | Qom silk and pictorial rugs |
| 80 | 1,306,000 | 843 | Pure silk masterpieces |
What knot density tells you
- Detail: higher raj allows finer curves, faces and small motifs.
- Weaving time: doubling the raj roughly quadruples the number of knots.
- Materials: very high raj is usually woven in silk or kork on a silk foundation.
What it does not tell you
Raj alone does not decide quality. A 30-raj tribal rug in good wool with natural dyes can be more valuable and durable than a 50-raj rug with poor wool and dyes. Look at the wool, the dyeing, the balance of the design and how straight the rug is woven.
The knot density of every Jalili Collection rug is recorded on its certificate. See also our Persian rug buying guide.