gsm to oz Converter
A 200 GSM fabric weighs about 5.9 ounces per square yard.
Quick answer: Divide the GSM by 33.9057. For example, 200 GSM is 5.899 oz/yd2, 100 GSM is 2.949 oz/yd2 and 300 GSM is 8.848 oz/yd2.
The GSM to oz formula
Ounces per square yard equal GSM divided by 33.9057.
The last column gives ounces per square foot.
Take 200 GSM. 200 ÷ 33.9057 gives 5.899 oz/yd2.
Take 100 GSM. 100 ÷ 33.9057 gives 2.949 oz/yd2.
Metric weight to US weight
GSM means grams per square metre, the mass of a piece of fabric that is one metre by one metre. Because it does not depend on the width of the roll, it is handy for comparing fabrics from different sellers (Minerva Patterns: Fabric weight, GSM and what it means for garments).
NIST gives 1 oz/yd2 as 33.90575 g/m2, so you divide GSM by that number to get ounces per square yard (Canvas Etc: Oz to GSM converter using the NIST factor).
How to convert GSM to oz step by step
- Read the weight in GSM.
- Divide it by 33.9057.
- Read the answer as ounces per square yard.
- Read ounces per square foot in the last column.
Example 1: 200 GSM
- Start with 200 GSM.
- 200 ÷ 33.9057 = 5.899.
- The fabric weight is 5.899 oz/yd2.
200 GSM = 5.899 oz/yd2
Example 2: 100 GSM
- Start with 100 GSM.
- 100 ÷ 33.9057 = 2.949.
- The fabric weight is 2.949 oz/yd2.
100 GSM = 2.949 oz/yd2
Example 3: 300 GSM
- Start with 300 GSM.
- 300 ÷ 33.9057 = 8.848.
- The fabric weight is 8.848 oz/yd2.
300 GSM = 8.848 oz/yd2
The three examples below use common sizes.
Each one shows the sum in full.
GSM to oz conversion table
| Weight in GSM | Ounces per square yard | Ounces per square foot |
|---|---|---|
| 50 GSM | 1.475 oz/yd2 | 0.1639 oz/ft2 |
| 80 GSM | 2.359 oz/yd2 | 0.2622 oz/ft2 |
| 100 GSM | 2.949 oz/yd2 | 0.3277 oz/ft2 |
| 120 GSM | 3.539 oz/yd2 | 0.3932 oz/ft2 |
| 150 GSM | 4.424 oz/yd2 | 0.4916 oz/ft2 |
| 180 GSM | 5.309 oz/yd2 | 0.5899 oz/ft2 |
| 200 GSM | 5.899 oz/yd2 | 0.6554 oz/ft2 |
| 250 GSM | 7.373 oz/yd2 | 0.8193 oz/ft2 |
| 300 GSM | 8.848 oz/yd2 | 0.9831 oz/ft2 |
| 350 GSM | 10.323 oz/yd2 | 1.147 oz/ft2 |
| 400 GSM | 11.797 oz/yd2 | 1.311 oz/ft2 |
| 500 GSM | 14.747 oz/yd2 | 1.639 oz/ft2 |
The highlighted row is the default of the calculator. The last column gives oz/ft2.
A quick mental shortcut for GSM to oz
A rough rule is to divide the GSM by 34. So 200 GSM is a little under 6 oz/yd2, and the exact answer is 5.8987.
Double the GSM and the ounces double.
Fabric weight classes
One guide groups woven apparel fabrics as very light under 100 GSM, light from 100 to 150, medium from 150 to 250, medium-heavy from 250 to 350 and heavy above 350 (Minerva Patterns: Fabric weight, GSM and what it means for garments).
The guide notes these ranges overlap and vary by fibre.
Worked examples
A 100 GSM fabric is about 2.95 oz/yd2, and a 150 GSM fabric is about 4.42 oz/yd2.
A 300 GSM fabric is about 8.85 oz/yd2, and a 400 GSM fabric is about 11.80 oz/yd2.
Per square yard or per linear yard
Check that an ounce figure is per square yard and not per running yard, especially for denim (Minerva Patterns: Fabric weight, GSM and what it means for garments).
A per linear yard weight depends on the width of the fabric, while GSM does not.
Ounces per square foot
The last column shows ounces per square foot. Since a square yard holds 9 square feet, 9 oz/yd2 is exactly 1 oz/ft2.
So 305.15 GSM is 1 oz/ft2.
Paper weights
GSM is also used for paper. The same sum turns an 80 GSM sheet into about 2.36 oz/yd2.
Paper is mostly quoted in GSM, so you rarely need ounces for it.
Quick conversion answers
| Conversion | Result |
|---|---|
| 200 GSM | 5.899 oz/yd2 |
| 100 GSM | 2.949 oz/yd2 |
| 300 GSM | 8.848 oz/yd2 |
| 150 GSM | 4.424 oz/yd2 |
Where this conversion is used
Sewists and buyers compare fabric weights from US and metric sellers.
Printers and crafters compare paper and card weights.
Common mistakes to avoid
- Mixing square yard with linear yard. Check the width.
- Multiplying instead of dividing. Divide GSM by 33.9057.
- Treating the classes as strict. The ranges overlap.
- Mixing GSM with thread count. They are different things.
Related converters
More GSM values
60 GSM is 1.77 oz/yd2. 75 GSM is 2.212 oz/yd2. 90 GSM is 2.654 oz/yd2.
130 GSM is 3.834 oz/yd2. 160 GSM is 4.719 oz/yd2. 220 GSM is 6.489 oz/yd2.
270 GSM is 7.963 oz/yd2. 450 GSM is 13.27 oz/yd2. 600 GSM is 17.7 oz/yd2.
Doubling the first number
120 GSM is 3.539 oz/yd2. 150 GSM is 4.424 oz/yd2. 180 GSM is 5.309 oz/yd2.
260 GSM is 7.668 oz/yd2. 320 GSM is 9.438 oz/yd2. 440 GSM is 12.98 oz/yd2.
540 GSM is 15.93 oz/yd2. 900 GSM is 26.54 oz/yd2. 1,200 GSM is 35.39 oz/yd2.
Comparing two fabrics
A 150 GSM fabric is about 4.42 oz/yd2, and a 250 GSM fabric is about 7.37 oz/yd2. The gap of 100 GSM is about 2.95 oz/yd2.
This shows that a step up of 100 GSM adds close to 3 ounces to every square yard.
Weight of a length of fabric
GSM makes it easy to weigh a piece. A roll 1.5 m wide and 10 m long covers 15 square metres, so at 200 GSM it weighs 3,000 g, which is 3 kg.
Check the answer by converting back. A fabric of 5.9 oz/yd2 times 33.9057 comes to about 200 GSM.
Quick rules to remember
As a rough guide, 100 GSM is close to 3 oz/yd2, 200 GSM is close to 6 oz/yd2 and 300 GSM is close to 9 oz/yd2. The exact values are 2.95, 5.90 and 8.85.
These anchors let you judge a fabric at a glance before you use the exact sum.
Frequently asked questions
How do I convert GSM to oz?
Divide the GSM by 33.9057 to get ounces per square yard.
What is 200 GSM in oz/yd2?
About 5.90 oz/yd2.
What is 300 GSM in oz/yd2?
About 8.85 oz/yd2.
What does GSM mean?
Grams per square metre.
Why check square yard?
A per linear yard figure depends on the fabric width.
What is 1 oz/ft2 in GSM?
About 305.15 GSM.
Sources
- Minerva Patterns: Fabric weight, GSM and what it means for garments (minervapatterns.com)
- Canvas Etc: Oz to GSM converter using the NIST factor (canvasetc.com)
