Fabric Weight Conversion
GSM and oz/yd² are the two units fabric weight gets listed in — convert between them instantly.
Rough weight-to-fabric-type reference
| GSM | oz/yd² | Typical fabric |
|---|---|---|
| Under 100 | Under ~3 | Voile, chiffon, lightweight lawn |
| 100–150 | ~3–4.4 | Quilting cotton, lightweight shirting |
| 150–220 | ~4.4–6.5 | Medium shirting, poplin, chambray |
| 220–300 | ~6.5–8.8 | Denim (bottomweight), twill |
| Over 300 | Over ~8.8 | Canvas, upholstery weight, heavy denim |
The exact conversion factor
1 oz/yd² = 33.906 g/m² (GSM), derived directly from the exact yard-to-meter and ounce-to-gram conversions — this isn't an approximation, so the numbers here match whatever a fabric's actual GSM or oz/yd² rating is.
Why fabric weight matters beyond "thick vs. thin"
Weight affects drape, structure, and how a pattern's ease reads on the body — a pattern drafted for a light quilting cotton will hang and fit differently in a heavy canvas even at the identical cut measurements. When a pattern specifies a weight range, matching it (rather than just matching the general fabric type) keeps the finished garment's silhouette closer to what the pattern was designed for.