Fabric GSM Converter
Fabric GSM Converter
g/m², oz/yd² and ounces per LINEAR yard — and the third of those depends on the roll width, which is why this is not a one-line conversion. A 12 oz denim is 407 g/m² whatever the width; a yard off the roll weighs a third more at 60 inches than at 45.
Fabric weight
a 12 oz denim on a 58-inch roll
Two yards, and only one of them is an area
- square yard
- an area, exactly 0.83612736 m². A weight per square yard needs no width
- linear yard
- 36 in of roll at whatever width it happens to be. A weight per linear yard is meaningless without it
- 33.90575
- the exact ratio of the avoirdupois ounce to the square yard. Both constants are exact, so this one is too
- denim oz
- oz/yd², not per linear yard. A 12 oz denim is 407 g/m²
- width
- usable width selvedge to selvedge. Nominal widths (44 in, 110 cm) are not conversions of each other
Worked example
a 12 oz denim on a 58-inch roll
The trade's “12 oz” means 12 ounces per SQUARE yard, so 12 × 33.90575 = 406.9 g/m²
That constant is exact arithmetic, not a measurement: an ounce is 28.349523125 g and a square yard is 0.83612736 m²
One linear yard of a 58-inch roll is 58 ÷ 36 = 1.6111 yd², so it weighs 12 × 1.6111 = 19.33 oz
In metric: 58 in is 1.4732 m, so a linear metre weighs 406.9 × 1.4732 = 599 g
The same denim at 45 in would be 15.00 oz a linear yard and at 60 in 20.00 — a third more cloth for the same number on the label
The same 12 oz denim on every standard roll width
| Width (in) | Width (cm) | What it usually is | Area of a linear yard (yd²) | Area of a linear metre (m²) | oz per linear yard | g per linear metre |
|---|---|---|---|---|---|---|
| 42 | 110 | quilting cotton, US mills | 1.1667 | 1.0668 | 14.00 | 434 |
| 44 | 110 | quilting cotton, UK and EU mills | 1.2222 | 1.1176 | 14.67 | 455 |
| 45 | 140 | dress fabric and broadcloth | 1.2500 | 1.1430 | 15.00 | 465 |
| 54 | 135 | drapery | 1.5000 | 1.3716 | 18.00 | 558 |
| 58 | 150 | knit and upholstery | 1.6111 | 1.4732 | 19.33 | 599 |
| 60 | 150 | upholstery, wide apparel cloth | 1.6667 | 1.5240 | 20.00 | 620 |
| 108 | 280 | wide-back quilting cotton | 3.0000 | 2.7432 | 36.00 | 1,116 |
Denim, where “oz” means ounces per SQUARE yard
| Band | As the trade says it | Computed from 33.906 (g/m²) | As the same source prints it (g/m²) | Difference |
|---|---|---|---|---|
| Lightweight denim | 6–9 oz | 203–305 | 204–305 | -0.6 / 0.2 |
| Mid-weight denim — “the sweet spot” | 10–14 oz | 339–475 | 340–475 | -0.9 / -0.3 |
| Heavyweight denim | 15 oz and up | 509 and up | 510 and up | -1.4 |
T-shirt jersey, and a published band table checked against itself
| Band | g/m² as printed | oz as printed | oz computed from the g/m² | Printed minus computed |
|---|---|---|---|---|
| Lightweight tee | 100–150 | 3.0–4.5 | 2.95–4.42 | -0.05 / -0.08 |
| Mid-weight tee | 150–180 | 4.5–5.5 | 4.42–5.31 | -0.08 / -0.19 |
| Heavyweight tee | 180–240 | 6.0–7.0 | 5.31–7.08 | -0.69 / 0.08 |
Towels, where the same GSM is the same unit
| What it is sold as | g/m² | oz/yd² |
|---|---|---|
| Quick-dry and travel towels — “thin and flat, closer to a large tea towel” | 300–400 | 8.85–11.80 |
| Hotel, gym and household bulk — “light but proper terry” | 400–550 | 11.80–16.22 |
| Retail “plush” and hotel luxury — dries overnight | 550–650 | 16.22–19.17 |
| Upper retail end and many spa ranges — “thick and heavy in the hand” | 650–750 | 19.17–22.12 |
| Spa and specialist — “very thick”, slow drying | 750–900 | 22.12–26.54 |
| Bath mats rather than body drying — “dense and mat-like” | 900 and up | 26.54 and up |
Named cloths, for sanity-checking a number
| Cloth | g/m² | oz/yd² |
|---|---|---|
| Cheesecloth | 40 | 1.18 |
| Muslin | 70–100 | 2.06–2.95 |
| Chiffon | 75–125 | 2.21–3.69 |
| Quilting cotton | 140 and up | 4.13 |
| Cotton jersey knit | 100–200 | 2.95–5.90 |
| Wool suiting | 210–300 | 6.19–8.85 |
| Denim | 130–550 | 3.83–16.22 |
| Hoodie fleece | 300–400 | 8.85–11.80 |
| Upholstery | 250–650 | 7.37–19.17 |
| Cotton towelling | 300–900 | 8.85–26.54 |
The three units, and which is which
| Unit | What it measures | Needs the width? | Who uses it |
|---|---|---|---|
| g/m² (GSM) | mass per unit AREA | no | everyone outside the US, and US mills for knits and towels |
| oz/yd² | mass per unit AREA | no | US apparel trade; this is what a denim “oz” number is |
| oz or lb per LINEAR yard | mass per unit LENGTH of roll | YES | US wovens sold by the yard, and freight |
| g or kg per LINEAR metre | mass per unit LENGTH of roll | YES | European rolls, sold by the metre at a stated width |
| yards per pound | the reciprocal, length per unit mass | YES | mills quoting yield |
| tex, denier, Nm, Ne | mass per length of a single YARN, not of cloth | no — different quantity entirely | spinners; see the yarn count converter |
A square yard is an area; a linear yard is not
Two of the units on this page are weights per unit area and two are weights per unit length, and confusing them is the commonest mistake in buying cloth. Grams per square metre and ounces per square yard both describe the fabric itself: they need nothing else, and the factor between them is exact arithmetic — an avoirdupois ounce is exactly 28.349523125 g, a square yard is exactly 0.83612736 m², so 1 oz/yd² is 33.90575 g/m² with no measurement in it. Ounces per linear yard and grams per linear metre describe a length of roll, and a length of roll is not an area until you know how wide it is.
That width is the reason this page can exist at all. One linear yard of 45-inch cloth is 1.25 square yards; one linear yard of 60-inch cloth is 1.667. Same cloth, same weight per square yard, and the second weighs a third more per yard bought — a third more money, a third more freight, a third more when the mill quotes yield. Standard widths run from 42 in quilting cotton to 108 in wide-back, so the spread is a factor of two and a half. No search engine can do that conversion, because the missing number is on the roll and nowhere else.
Which ounce does the denim trade mean? The square-yard one. A 12 oz denim weighs twelve ounces per square yard, which is 407 g/m²; the source of the published weight bands says it in terms, “an ounce tells you how much a square yard of fabric weighs”, and its own printed gram figures reproduce the 33.906 factor at every band boundary. The same applies to canvas and duck. So a denim number converts without a width, and only the linear question needs one.
A towel’s GSM and a T-shirt’s GSM are the same unit as a shirting GSM — grams per square metre of finished dry fabric — and the numbers look unfamiliar only because terry is four or five times the weight of shirting per unit area. Those are also the highest-volume questions this page gets, so both band tables are here. One warning that came out of checking them: a published T-shirt band table prints 180 g/m² as the mid-to-heavy boundary in one column and 6 oz in the other, and 180 g/m² is really 5.31 oz while 6 oz is 203. Whole-ounce rounding, but 12% of a shirt.
What this page will not do is convert a fabric weight into a yarn count. Tex, denier, Nm and Ne are mass per unit length of a single thread; g/m² is mass per unit area of cloth. Getting from one to the other needs the threads per inch in warp and weft and the crimp they took in weaving, none of which a converter can know, so there is no factor and this page offers none. The yarn count converter owns the yarn side of that boundary. For the paper-trade version of exactly the same area-versus-sheet confusion see the paper weight converter, where a pound depends on which basic sheet it was weighed on.
Frequently asked questions
What is 1 oz/yd² in GSM?
33.90575 g/m², and it is exact rather than approximate: an avoirdupois ounce is exactly 28.349523125 g and a square yard is exactly 0.83612736 m², so their ratio has no measurement in it. Most charts print 33.906 or 33.91; the same number comes out of the exact pound divided by sixteen, which is a useful second check.
What does the “oz” on denim mean?
Ounces per square yard. A 12 oz denim weighs 12 ounces per square yard, which is 407 g/m²; a 14 oz is 475. It does NOT mean the weight of a yard off the roll, which would depend on the roll’s width. Published bands put lightweight at 6 to 9 oz, mid-weight at 10 to 14 and heavyweight at 15 and up.
Why do I need the fabric width?
Because a linear yard is a length, not an area. A yard off a 45-inch roll is 1.25 yd²; a yard off a 60-inch roll is 1.667 yd² — a third more cloth at the same weight per square yard, so a third more weight, a third more money and a third more freight. Any quote in oz or lb per linear yard, or in g per linear metre, is incomplete without the width beside it.
Is a towel’s GSM the same unit as a shirt’s?
Yes, exactly the same: grams per square metre of finished dry fabric. The numbers look different only because terry is a much heavier construction — a 600 GSM bath towel is 17.7 oz/yd² against a T-shirt’s 4 or 5. Nothing about towel GSM is special; the unit is just more often quoted there because it is the main thing distinguishing one towel from another.
What GSM is a good T-shirt?
Published bands put lightweight tees at 100 to 150 g/m², mid-weight at 150 to 180 and heavyweight at 180 to 240 and up. Watch the unit when a listing quotes ounces: the same table that prints 180 g/m² as the mid/heavy boundary also prints that boundary as 6 oz, and 180 g/m² is really 5.31 oz. Six ounces is 203 g/m², a genuinely heavier shirt.
How is fabric weight different from yarn count?
They are different physical quantities. Fabric weight is mass per unit AREA of cloth; a yarn count — tex, denier, Nm, Ne — is mass per unit LENGTH of a single thread. No factor converts between them, because getting from one to the other needs the threads per inch in warp and weft and the crimp they took in weaving. The yarn count converter handles the yarn side; this page handles the cloth side; nothing bridges them.
How do I work out yards per pound?
It is the reciprocal of pounds per linear yard, so it needs the width too. At 407 g/m² on a 58-inch roll a linear yard weighs 1.208 lb, so a pound is 0.828 linear yards. Mills quote yield this way because it is what they are actually selling.
Related calculators
References
- Fashion-Incubator, Fabric Weight and Conversions (read 27 September 2026), which derives the constant this page is built on from the exact ounce and the exact yard — “1 oz/yd2 = 28.3495231g/.83612736 m2 = 33.90574744 g/m2” — and states the linear-yard trap in terms: “every linear yard of goods 54″ wide covers an area of 1.5 square yards.”
- FibreCalcs, Standard Fabric Widths Guide (read 27 September 2026), for the widths the selector offers and what each is: quilting cotton 42 to 44 in (110 cm), dress fabric 44 to 45 in (140 cm), drapery 54 in, knit and upholstery 58 to 60 in (150 cm), wide-back 108 in (280 cm). It also states the sales convention: fabric is sold “by the linear yard or metre at the stated width”.
- sanvt, Denim Oz: Guide to Meaning, Weight & Differences vs GSM (read 27 September 2026), which settles which ounce the denim trade means — “an ounce tells you how much a square yard of fabric weighs” — gives “1 ounce (oz/yd²) ≈ 33.91 GSM”, and prints the bands: lightweight 6 to 9 oz, mid-weight 10 to 14 oz (“the sweet spot”), heavyweight 15 oz and up.
- Kemet Cotton, Towel GSM Explained (read 27 September 2026), for the towel bands and for the confirmation that a towel’s GSM is the same unit as any other fabric’s: “GSM stands for grams per square meter. It is the weight of one square meter of the finished fabric, dry.”
- US Apparel Wholesale, T-Shirt Fabric Weight Guide (read 27 September 2026), for the jersey bands — lightweight 100 to 150 GSM (3 to 4.5 oz), mid-weight 150 to 180 (4.5 to 5.5 oz), heavyweight 180 to 240+ (6 to 7+ oz) — whose two columns agree with the 33.906 factor to better than 2%, and for the same point stated generally: GSM “applies to all fabric types, not just t-shirts”.
- Silver Bobbin, What Is GSM of Fabric? (read 27 September 2026), for the general weight classes and the named-cloth table: muslin 70 to 100, cotton jersey 100 to 200, wool suiting 210 to 300, denim 130 to 550, hoodie fleece 300 to 400, upholstery 250 to 650, cotton towelling 300 to 900 g/m².