oz to gsm Converter
An 8 oz per square yard fabric weighs about 271 GSM.
Quick answer: Multiply the ounces per square yard by 33.9057. For example, 8 oz/yd2 is 271.25 GSM, 7 oz/yd2 is 237.34 GSM and 12 oz/yd2 is 406.87 GSM.
The oz to GSM formula
GSM equals ounces per square yard times 33.9057.
The last column gives kilograms per square metre.
Take 8 oz/yd2. 8 × 33.9057 gives 271.25 GSM.
Take 7 oz/yd2. 7 × 33.9057 gives 237.34 GSM.
US weight to metric weight
NIST gives 1 oz/yd2 as 0.03390575 kg/m2, which is 33.90575 g/m2 (Canvas Etc: Oz to GSM converter using the NIST factor).
So multiply ounces per square yard by that factor to get GSM. A common shortcut is to multiply by about 34.
How to convert oz to GSM step by step
- Read the weight in ounces per square yard.
- Multiply it by 33.9057.
- Read the answer in GSM.
- Read kg per square metre in the last column.
Example 1: 8 oz/yd2
- Start with 8 oz/yd2.
- 8 × 33.9057 = 271.25.
- The fabric weight is 271.25 GSM.
8 oz/yd2 = 271.25 GSM
Example 2: 7 oz/yd2
- Start with 7 oz/yd2.
- 7 × 33.9057 = 237.34.
- The fabric weight is 237.34 GSM.
7 oz/yd2 = 237.34 GSM
Example 3: 12 oz/yd2
- Start with 12 oz/yd2.
- 12 × 33.9057 = 406.87.
- The fabric weight is 406.87 GSM.
12 oz/yd2 = 406.87 GSM
The three examples below use common sizes.
Each one shows the sum in full.
oz to GSM conversion table
| Ounces per square yard | GSM | Kilograms per square metre |
|---|---|---|
| 1 oz/yd2 | 33.906 GSM | 0.0339 kg/m2 |
| 2 oz/yd2 | 67.811 GSM | 0.0678 kg/m2 |
| 3 oz/yd2 | 101.72 GSM | 0.1017 kg/m2 |
| 4 oz/yd2 | 135.62 GSM | 0.1356 kg/m2 |
| 5 oz/yd2 | 169.53 GSM | 0.1695 kg/m2 |
| 6 oz/yd2 | 203.43 GSM | 0.2034 kg/m2 |
| 7 oz/yd2 | 237.34 GSM | 0.2373 kg/m2 |
| 8 oz/yd2 | 271.25 GSM | 0.2712 kg/m2 |
| 10 oz/yd2 | 339.06 GSM | 0.3391 kg/m2 |
| 12 oz/yd2 | 406.87 GSM | 0.4069 kg/m2 |
| 14 oz/yd2 | 474.68 GSM | 0.4747 kg/m2 |
| 16 oz/yd2 | 542.49 GSM | 0.5425 kg/m2 |
The highlighted row is the default of the calculator. The last column gives kg/m2.
A quick mental shortcut for oz to GSM
A rough rule is to multiply the ounces by 34. So 8 oz/yd2 is about 272 GSM, and the exact answer is 271.25.
Double the ounces and the GSM doubles.
Worked examples
A 7 oz/yd2 fabric is about 237.34 GSM, and an 8 oz/yd2 fabric is about 271.25 GSM (Canvas Etc: Oz to GSM converter using the NIST factor).
A 12 oz/yd2 fabric is about 406.87 GSM, and a 16 oz/yd2 fabric is about 542.49 GSM.
If the weight is per linear yard
Some sellers quote ounces per linear yard. First find ounces per square yard by multiplying the ounces by 36 and dividing by the width in inches, then multiply by 33.9057 (Canvas Etc: Oz to GSM converter using the NIST factor).
For example, 8 oz per linear yard at 60 inches wide is 4.8 oz/yd2, which is about 162.75 GSM.
Heavy fabrics
A 13 oz/yd2 fabric is about 440.77 GSM, and an 18 oz/yd2 fabric is about 610.30 GSM. A 24 oz/yd2 fabric is about 813.74 GSM.
Fabrics above 350 GSM fall in the heavy class of one guide (Minerva Patterns: Fabric weight, GSM and what it means for garments).
Why width does not matter for GSM
GSM is the mass of a one metre by one metre square, so it does not depend on the width of the roll. That makes it handy for comparing fabrics.
A per linear yard figure changes with the width, so convert it before you compare.
Going back
To turn GSM back into ounces per square yard, divide by 33.9057. For example, 300 GSM is about 8.85 oz/yd2.
The GSM to oz page does this for you.
Quick conversion answers
| Conversion | Result |
|---|---|
| 8 oz/yd2 | 271.25 GSM |
| 7 oz/yd2 | 237.34 GSM |
| 12 oz/yd2 | 406.87 GSM |
| 4 oz/yd2 | 135.62 GSM |
Where this conversion is used
Buyers and sewists compare US and metric fabric weights.
Makers of canvas and upholstery check weights from US suppliers.
Common mistakes to avoid
- Mixing square yard with linear yard. Convert using the width.
- Dividing instead of multiplying. Multiply by 33.9057.
- Mixing ounces of weight with fluid ounces. This is weight.
- Rounding too early. Keep the factor to four places.
Related converters
More ounce weights
2.5 oz/yd2 is 84.76 GSM. 4.8 oz/yd2 is 162.7 GSM. 9 oz/yd2 is 305.2 GSM.
11 oz/yd2 is 373 GSM. 13 oz/yd2 is 440.8 GSM. 18 oz/yd2 is 610.3 GSM.
24 oz/yd2 is 813.7 GSM. 0.5 oz/yd2 is 16.95 GSM. 20 oz/yd2 is 678.1 GSM.
Doubling the first number
5 oz/yd2 is 169.5 GSM. 9.6 oz/yd2 is 325.5 GSM. 18 oz/yd2 is 610.3 GSM.
22 oz/yd2 is 745.9 GSM. 26 oz/yd2 is 881.5 GSM. 36 oz/yd2 is 1,221 GSM.
48 oz/yd2 is 1,627 GSM. 1 oz/yd2 is 33.91 GSM. 40 oz/yd2 is 1,356 GSM.
Comparing two fabrics
A 10 oz/yd2 fabric is about 339.06 GSM, and a 12 oz/yd2 fabric is about 406.87 GSM. The gap is about 67.81 GSM.
Each extra ounce per square yard adds close to 34 GSM.
Weight of a piece
Once you have the GSM, you can weigh a piece. Ten square metres of an 8 oz/yd2 fabric weighs about 2,712 g, which is about 2.71 kg.
Multiply the GSM by the area in square metres to get grams.
Quick rules to remember
As a rough guide, 4 oz/yd2 is close to 136 GSM, 6 oz/yd2 is close to 203 GSM and 10 oz/yd2 is close to 339 GSM.
These anchors let you judge a fabric at a glance before you use the exact sum. Round only at the end of the work.
Frequently asked questions
How do I convert oz/yd2 to GSM?
Multiply by 33.9057.
What is 8 oz/yd2 in GSM?
About 271.25 GSM.
What is 7 oz/yd2 in GSM?
About 237.34 GSM.
How do I handle a per linear yard weight?
Multiply by 36, divide by the width in inches, then multiply by 33.9057.
Why does width matter for linear yard?
A wider fabric weighs more per yard of length.
What is the NIST factor?
1 oz/yd2 is 33.90575 g/m2.
Sources
- Canvas Etc: Oz to GSM converter using the NIST factor (canvasetc.com)
- Minerva Patterns: Fabric weight, GSM and what it means for garments (minervapatterns.com)
