Fabric Weight Converter
Switch fabric weight between GSM and oz per square yard.
What it does
Fabric weight reports mass per area. Metric mills quote grams per square meter, US mills quote ounces per square yard. The two differ only by mass and area units.
The tool above converts between gsm and oz/yd2. The defaults convert 150 gsm, so the page opens showing 4.424 oz/yd2. Swap units to update the result.
The link is exact from definitions: 1 ounce is 28.349523125 grams, 1 yard is 0.9144 meters, so 1 square yard is 0.83612736 square meters. Dividing gives 33.905747 grams per square meter in one ounce per square yard.
Use gsm for tech packs and imports, oz for US denim and canvas. T-shirt jersey near 150 gsm, denim 300 plus, canvas higher. Hand feel also needs weave and fiber, not just weight.
This page shows the factor, one full hand checked example at 150 gsm, a reference table, and practice checks that run through the tool.
How to use
- Type the weight number, for example 150.
- Pick the starting unit in From unit.
- Pick the target unit in To unit.
- Read the main result with unit name.
- Compare swatches at the same weight across weaves.
- Check spec sheets for GSM versus oz before ordering.
Formula
- gsm
- Grams per square meter.
- oz/yd2
- Ounces per square yard.
- 33.905747
- GSM in one oz/yd2, exact by definition.
Factors use exact ounce, yard, and meter definitions. Same weight in different weaves can drape very differently.
Worked example
Example: 150 gsm to oz/yd2
Jersey spec 150 grams per square meter. Express in US units.
- Write 150, from gsm, to oz/yd2.
- Divide: 150 / 33.905747 = 4.424036.
- Round to four decimals: 4.424 oz/yd2.
- Check: 4.424 x 33.905747 = 150.00 gsm.
- Read as light shirting weight.
- Order swatch to confirm hand.
Reference table
| Fabric | gsm | oz/yd2 |
|---|---|---|
| Voile | 80 | 2.36 |
| Jersey | 150 | 4.424 |
| Denim | 300 | 8.848 |
| Canvas | 400 | 11.797 |
Limits
- Weight only. Weave and fiber set hand too.
- Two units only here.
- Four decimals suit specs. Cutting needs less.
- Coated weights include finish mass.
Common mistakes
- Reading oz/yd2 as oz per linear yard.
- Multiplying by 33.9 when converting gsm to oz.
- Comparing weights across different weaves as warmth.
- Ignoring finish mass in coated weights.
- Rounding before converting.
Try it yourself
Quick checks. Answers sit tucked under each question.
5 oz/yd2 in gsm?
5 x 33.905747 = 169.5287 gsm.
80 gsm in oz?
80 / 33.905747 = 2.3596 oz/yd2.
Questions
150 gsm in oz?
4.424 oz/yd2.
GSM or oz?
Metric specs use gsm, US mills often oz/yd2.
Heavier warmer?
Often, but weave and fiber matter too.
Exact factor?
33.905747 gsm per oz/yd2.
Denim?
Often 300 gsm plus, near 9 oz.
Swatch?
Yes. Weight alone does not fix drape.