Fabric GSM Calculator
GSM (grams per square meter) is how fabric weight is quoted in most of the world, and it is the number a mill or factory will ask for first. Cut a swatch, weigh it, and this calculator turns it into GSM and oz/yd².
How to measure a swatch
- Cut a sample. A GSM cutter gives you a 100 cm² circle. Without one, cut a 10 × 10 cm square (4 × 4 in) with a ruler, a rotary cutter and a cutting mat.
- Weigh it. A pocket scale that reads 0.01 g is enough. Cut three samples from different places across the roll and average them, because knit fabric varies from selvage to selvage.
- Do not stretch or fold the sample. If it came off a roll under tension, let it relax for a few minutes first. A stretched swatch reads lighter than the fabric really is.
- Read the result. The formula is simple: GSM = weight of the sample (g) ÷ area of the sample (m²). A 10 × 10 cm square is 0.01 m², so 1.8 g of jersey is 180 GSM, and the same square of fleece at 2.5 g is 250 GSM.
Already have a number in GSM and need it in ounces? Use the GSM to oz converter.
Typical fabric weight by garment
Use this as a sanity check on your swatch. If your heavyweight tee measures 150 GSM, either the fabric is not what you ordered or the sample was mis-cut.
| Garment | Typical weight | In ounces | Why |
|---|---|---|---|
| T-shirt, lightweight | 140–160 GSM | 4.13–4.72 oz/yd² | Summer and fashion tees. |
| T-shirt, standard | 180–200 GSM | 5.31–5.90 oz/yd² | The most common retail tee weight. |
| T-shirt, heavyweight | 220–260 GSM | 6.49–7.67 oz/yd² | Boxy streetwear tees that hold their shape. |
| Polo shirt | 200–240 GSM | 5.90–7.08 oz/yd² | Cotton pique, usually with a flat-knit collar and cuffs. |
| Sweatshirt / crewneck | 300–400 GSM | 8.85–11.80 oz/yd² | Brushed-back fleece: warm and structured. |
| Hoodie | 280–400 GSM | 8.26–11.80 oz/yd² | The weight decides whether a hoodie drapes or stands up. |
| Joggers | 280–320 GSM | 8.26–9.44 oz/yd² | Heavy enough to hang straight; often the same fleece as the hoodie. |
| Shorts (French terry) | 260–300 GSM | 7.67–8.85 oz/yd² | Lighter than fleece so the short does not feel bulky. |
Ranges are typical values for knit garments. Weight varies by mill, yarn and finish, so always confirm it against the fabric you actually receive. Need the fabric itself? Ask us for a quote — we are a knit fabric mill in Guangzhou.
FAQ
What does GSM mean in fabric?
Grams per square meter: the weight of a piece of fabric one meter by one meter. It is the standard way mills and factories describe how heavy a fabric is, for knits and wovens alike.
How accurate is a swatch calculation?
The cut matters more than the scale. A 1 mm error on a 10 cm square changes the result by roughly 2%, and a sample cut from a roll under tension weighs light. Cut three samples, weigh each one and average them.
What GSM is a good t-shirt?
180–200 GSM cotton jersey is the usual retail weight: opaque but still comfortable in summer. 140–160 GSM reads as a light fashion tee, while 220–260 GSM is a heavyweight tee.
Does a higher GSM mean better quality?
No. GSM only describes weight. A 240 GSM tee is not automatically better than a 180 GSM one: it is warmer and holds its shape more, and it uses more fabric, so it costs more.
Can I use this for woven fabric?
Yes. GSM is used for wovens too, and the calculation is the same. Just cut your sample away from the selvage and from any print or coating.
Need fabric or a sample made? Ask us for a quote.