Qom (Ghom) knot density: KPSI, knots/m² and raj

By Hassan Farahani, MMA Last reviewed: 1 November 2026

Updated November 2026 · sources linked

At a glance

One square inch measures 6.4516 cm². 100 KPSI therefore corresponds to roughly 15.5 knots per cm² or 155,000 knots per m².
Raj is not a measure of area; it counts knots along a length. Converting it into an area requires an assumption.
At least three definitions of raj are in circulation: the Iranica gives a gereh of 6.25 to 6.95 cm, Wikipedia and dealers give 7 cm.
European auction houses usually state modern Qom (Ghom) silk at 800,000 to 1,200,000 knots per m², that is, about 520 to 775 KPSI.
Raj figures from Qom itself exist: 65 raj (leading product of the province in 2006/07), 75 raj (Jamshidi, formerly), 100–110 raj (Jamshidi today) and a single piece with 200 raj.

Hardly any figure is cited as often for Qom carpets (Ghom, Qum, Kum; Persian قم) as knot density. It appears in three systems: knots per square inch (KPSI) in the English-speaking trade, knots per m² or dm² in Europe, and raj in Iran. The figures look entirely different and often mean the same thing. This article offers a conversion table, explains the definitions of raj and shows why density figures should be read with caution.

The units

Knots per m² or dm². The German Wikipedia gives knots per square decimetre as the usual measure. English-language catalogues add KPSI (Wikipedia: Perserteppich). The Dorotheum in Vienna states density in knots per m², for instance “c. 1. mill. kts/sqm” (Dorotheum). One m² has 100 dm² and 10,000 cm².

Knots per cm². The London auction house Chiswick counts the two directions separately, for instance at approximately 11 × 10 knots per cm² (Chiswick, Lot 84). This means 11 knots side by side times 10 knots one above the other, that is, 110 knots per cm².

KPSI. The English Wikipedia defines KPSI as the knots counted vertically along one inch times the knots counted horizontally over the same area (Wikipedia: Knot density). The German Wikipedia gives the rule of thumb: knots per dm² divided by 15.5 gives KPSI.

Raj. The Encyclopaedia Iranica defines raj as the number of rows of knots per lengthwise gereh (Iranica, Carpets iii). Gereh literally means “knot” and is a measure of length, one sixteenth of the ell (zar’). Raj thus measures a length, not an area.

Examples in the trade: Qom silk rugs at BazarPort (our own shop)

Video from Hassan Farahani’s YouTube channel (Teppichbazar) Playing loads the video from YouTube (Google), which transfers data to Google.

The definition of raj used in this article

For the table below: raj = the number of knots over 7 cm, counted in one direction. To derive an area density from this, it is assumed that there are equal numbers of knots horizontally and vertically. The formula is then: knots per cm² = (raj ÷ 7)².

The 7 cm follow the English Wikipedia, which gives a gereh as about 7.0 cm (Wikipedia: Knot density), and the carpet trade (Bakhtiyar, trade claim; Jupiter International, trade claim). The assumption of equal density in both directions is a simplification. The German Wikipedia describes a ratio of 1:1 as common in very fine silk carpets from Kashan (Wikipedia: Perserteppich). In many carpets, however, the ratio is unequal. In that case any raj conversion gives only an approximate value.

The sources disagree

Length of the measured section. The Iranica gives 6.25 to 6.95 cm for the gereh (Carpets iii). The English Wikipedia gives about 7.0 cm (Knot density). Bakhtiyar counts raj over 7 cm and a second unit, kheft, over 6.5 cm, which according to the site is customary above all in Isfahan (Bakhtiyar). Direction of counting. The Iranica counts rows of knots lengthwise, that is, in the direction of the warp. Bakhtiyar and Jupiter count across the width (Jupiter). Where density is unequal, the two methods yield different raj values for the same carpet. Consequence. The same carpet with 1,000,000 knots per m² has 70 raj by the 7-cm definition, roughly 65 by 6.5 cm and roughly 62 by 6.25 cm. A raj figure without a definition is therefore imprecise by around ten per cent.

Conversion table

All values are rounded. Basis: 1 square inch = 6.4516 cm²; raj assuming equal density in both directions.

KPSI	Knots/cm²	Knots/dm²	Knots/m²	Raj (7 cm)	Kheft (6.5 cm)	Raj according to the Iranica (6.25–6.95 cm)
100	15,5	1.550	155.000	28	26	25–27
200	31	3.100	310.000	39	36	35–39
300	46,5	4.650	465.000	48	44	43–47
400	62	6.200	620.000	55	51	49–55
500	77,5	7.750	775.000	62	57	55–61
600	93	9.300	930.000	68	63	60–67
700	108,5	10.850	1.085.000	73	68	65–72
800	124	12.400	1.240.000	78	72	70–77
900	139,5	13.950	1.395.000	83	77	74–82
1.000	155	15.500	1.550.000	87	81	78–87
1.200	186	18.600	1.860.000	95	89	85–95

Conversely, starting from the figures of European auction houses:

Knots/m²	Knots/cm²	KPSI	Raj (7 cm)	Kheft (6.5 cm)
500.000	50	323	49	46
800.000	80	516	63	58
1.000.000	100	645	70	65
1.200.000	120	774	77	71
1.500.000	150	968	86	80
2.000.000	200	1.290	99	92

As a check: Jupiter International assigns 60 to 70 raj to a density of up to about 900,000 knots per m² (Jupiter, trade claim). According to the formula, 60 raj gives roughly 735,000 and 70 raj exactly 1,000,000 knots per m². The trade claim lies in the same range.

What Qom carpets actually measure

Auction catalogues

The most reliable public figures come from auction catalogues. They are rounded, but recorded by specialists on the object.

House, date	Object	Catalogue figure	≈ KPSI	≈ Raj (7 cm)
Dorotheum, 21.10.2020	Ghom silk, hunting scenes, approx. 395 × 290 cm	approx. 800,000/m²	516	63
Dorotheum, 23.03.2016	Ghom silk, approx. 400 × 297 cm	approx. 1 million/m²	645	70
Chiswick, 27.01.2026	Silk Qum, approx. 345 × 243 cm	approx. 10 × 10/cm²	645	70
Chiswick, 24.03.2026	Silk Qum, approx. 147 × 98 cm	approx. 11 × 10/cm²	710	73
Nagel, 27.02.2019	Silk Ghom, 340 × 250 cm	over 1 to 1.2 million/m²	645–774	70–77
Dorotheum, 24.02.2023	“Ghom silk 11 x 11”, approx. 98 × 43 cm	approx. 1.2 million/m²	774	77
Dorotheum, 2025	Ghom silk, approx. 300 × 207 cm	approx. 1.2 million/m²	774	77

Sources: Dorotheum 2020; Dorotheum 2016; Chiswick Lot 76; Chiswick Lot 84; Nagel via veryimportantlot; Dorotheum 2023; Dorotheum 2025.

The title “Ghom silk 11 x 11” shows a notation that is widespread in the trade. What is meant is 11 knots per centimetre in both directions. This gives 121 knots per cm², that is, roughly 1.2 million per m². The Dorotheum’s catalogue figure agrees with this.

A further example with known dimensions is the state gift to Japan’s Prime Minister in 2019. According to Wikipedia, the carpet has more than four million knots over 205 × 205 cm (Wikipedia: Qom rug). This gives roughly 950,000 knots per m², about 615 KPSI or 68 raj by the 7-cm definition.

Raj figures from Qom

Persian sources now give concrete raj values for Qom. None of them says over what length and in which direction the count was made. The conversion below therefore assumes both common lengths and equal density in both directions.

Source	Figure	Type of source	≈ knots/m² (7 cm)	≈ KPSI (7 cm)	≈ knots/m² (6.5 cm)
Goljaam, study of Qom province, data 2006/07	65 raj, silk warp, pile of silk and kork, leading product of the province	specialist journal	860.000	556	1.000.000
Mohammad Jamshidi, according to his son	75 raj, the father’s earlier quality	oral history	1.150.000	741	1.330.000
Alireza Jamshidi	100–110 raj, the sons’ present-day quality	oral history	2.040.000–2.470.000	1.317–1.593	2.370.000–2.860.000
Alireza Jamshidi	200 raj, a single piece, on the loom for ten years	oral history	8.160.000	5.267	9.470.000
Hossein Erami brand	fine knotting over 100 raj	company portrait	over 2,040,000	over 1,317	over 2,370,000

Sources: Goljaam; Hawzah News, 20.10.2022; carpetour.net (the firm’s own statement).

The values of 65 and 75 raj are consistent with the auction catalogues at 800,000 to 1,200,000 knots per m². The values from 100 raj upwards, by contrast, clearly exceed every auction lot examined. There are two possible explanations for this. Either the figure counts only one direction and the other is less dense. Or these are rare top pieces that do not come to auction. The sources do not allow a decision between the two.

Trade claims

The trade claims diverge considerably more.

Source	Figure	Converted
rugs.net (trade claim)	typically 400–700 KPSI; finest 900–1,000+; pure silk elsewhere 650–1,000 or 400–1,000+; below 200 “not a quality Qum”	620,000–1,085,000/m² typical
Bizsan (trade claim)	average 700,000–1,000,000/m²; top 1.2–2 million/m²	452–645 KPSI; top 774–1,290
persianrugs.com.au (trade claim)	up to 1,200 KPSI	1,860,000/m²
Djoharian (trade claim), kheshti design	approx. 650 KPSI	approx. 1,008,000/m²
rugs.net, Kashizadeh listing (trade claim)	approx. 1,000 KPSI; about twelve knots per centimetre	12 × 12/cm² would give 929 KPSI

Sources: rugs.net guide; bizsan.hu; persianrugs.com.au; Djoharian; rugs.net Kashizadeh.

The gap is striking. No auction lot examined gives more than about 1.2 million knots per m² for Qom, that is, roughly 775 KPSI. Several dealers advertise 1,000 KPSI and more. This need not be wrong. It does show, however, that trade figures and catalogue figures are not readily comparable. For comparison: one dealer gives 300 to 600 KPSI for kork Qom with a wool pile (rugs.net); more on this in the article Qom (Ghom) in kork wool on a silk warp.

Counting correctly

Counting is best done on the back, advises the German Wikipedia (Wikipedia: Perserteppich). This is where a typical source of error lies. Where the warps lie flat, both loops of a knot are visible. Together they count as one knot. Anyone who counts each loop doubles the horizontal figure.

With offset warps, one loop is concealed. The Iranica describes this construction with wefts of unequal tension. It produces two warp levels, and on the back one part of the knot is at least partly hidden (Iranica, Carpets iii). Here only one loop per knot is visible.

The German Wikipedia also recommends stating the horizontal and vertical counts separately. This reveals more than a single area figure. Anyone counting for themselves should therefore note two figures and multiply only afterwards. The figure “11 × 10 per cm²” in the Chiswick catalogue is structured in exactly this way.

What density does and does not tell you

Density shows fineness and the labour involved. Christie’s puts it simply: the more knots, the finer the carpet and the finer the possible design (Christie’s Collecting Guide). The German Wikipedia adds that artistic value depends hardly at all on the knot count. Sotheby’s even calls fineness a disadvantage at times, because very fine knotting can lose the free drawing of older village carpets (Sotheby’s).

Common quality scales are of little help with Qom. The English Wikipedia calls 330 KPSI and above “very good” (Wikipedia: Knot density). Almost every silk Qom lies above this. Bakhtiyar classes 85 raj and above as “very high” (Bakhtiyar, trade claim). By the 7-cm formula this would correspond to roughly 1.47 million knots per m². No Qom auction lot examined reaches this value. The oral history of the Jamshidi family gives considerably more, at 100 to 110 raj.

Raj values in the Western trade almost always refer to Tabriz. The raj columns of the conversion table are therefore conversions. Genuine raj figures from Qom appear only in the table “Raj figures from Qom”.