GSM Calculator & Fabric Weight Converter

GSM means grams per square metre. It measures the mass of one square metre of fabric and gives brands, mills and manufacturers a common way to describe fabric weight.

GSM equals sample weight in grams divided by sample area in square metres. A 10 × 10 cm swatch has an area of 0.01 m², so a 3.2 g swatch equals 320 GSM.

Divide GSM by 33.9057. For example, 320 GSM is about 9.44 oz/yd². To convert oz/yd² to GSM, multiply by 33.9057.

Often, but not always. Thickness also depends on yarn size, knit or weave structure, brushing, loft and compression. A brushed fleece can feel thicker than a dense interlock at a similar GSM.

No. GSM is a weight measurement, not a quality grade. Fiber quality, yarn, knitting or weaving, finishing, shrinkage control, colorfastness and sewing quality also matter.

It can. Shrinkage changes the fabric area, while moisture and finishing can change measured mass. For production decisions, compare fabric using an agreed conditioning and test method and confirm the washed sample as well as the original sample.

For many tops, lighter fabrics around 120–190 GSM are common because they can feel less bulky and more breathable. The best choice still depends on fiber, knit, color, fit and how much coverage the garment needs.

Winter sweatshirts and hoodies often use roughly 300–500+ GSM fabrics, especially fleece and dense French Terry. Warmth also depends on brushing, fiber, layers and garment construction, so GSM alone is not a thermal rating.

A practical range for many T-shirts is about 140–220 GSM. Premium or structured T-shirts often move into 200–260 GSM, while heavyweight streetwear tees may use roughly 220–320 GSM depending on the silhouette and construction.

Yes, 180 GSM is a common all-round T-shirt weight. It can provide a balance of comfort, coverage and everyday wear, especially in cotton single jersey.

220 GSM is a popular starting point for a more substantial premium tee. It usually gives more body and opacity than a lighter jersey, but the yarn, knit density and finish still determine whether it actually feels premium.

Many oversized or heavyweight streetwear T-shirts use roughly 220–300 GSM, with some going higher. The pattern, shoulder drop, neck rib and fabric recovery should be developed together with the GSM.

300 GSM is a useful midweight hoodie range, especially for French Terry or lighter fleece. It can work well for layering or milder climates. Heavy streetwear hoodies often move higher.

400 GSM is a common heavyweight hoodie target when a brand wants more structure and a substantial hand-feel. Whether it feels soft, stiff, warm or bulky depends on construction, fiber and finish.

500 GSM is very heavy for most apparel. It can create a dense, structured hoodie with strong physical presence, but it also increases fabric mass, cost and shipping weight and may be too warm or bulky for some customers.

French Terry sweatshirts commonly sit around 240–360 GSM, while brushed fleece sweatshirts often use roughly 280–420 GSM. Choose according to climate, fit, warmth and the hand-feel you want.

Many polo programs use roughly 180–260 GSM piqué or interlock. A lighter polo can feel more breathable, while a denser fabric can give more body and shape retention.

Joggers and sweatpants often use about 260–420 GSM French Terry or fleece. Lighter weights suit training or warmer climates; heavier weights create more structure and warmth.

Performance tops and lightweight sportswear often use roughly 120–220 GSM polyester, nylon or blended knits. Stretch, moisture management, recovery and construction are usually more important than chasing a high GSM.

French Terry typically has loops on the inside, while fleece is brushed to create a raised nap. Fleece can therefore feel warmer, softer and thicker even when the GSM is similar.

Start with the customer and product, not the highest number. For a first collection, choose a proven middle range for the garment—such as 180–220 GSM for an everyday tee or 300–380 GSM for a hoodie—then adjust after sampling, wash testing and customer feedback.

Usually not. Premium perception comes from the whole product: fabric quality, fit, stitching, finishing, trims, print or embroidery and consistency. A very heavy fabric can raise cost and reduce comfort without improving the product for your target customer.

Higher GSM generally means more fabric mass is used for the same garment area, so material cost can increase. It can also affect cutting, sewing, decoration, packing and freight. Exact cost depends on fabric price per kilogram or metre, yield and construction.

Yes. Higher GSM usually increases finished garment weight, which can increase carton weight and freight cost. For DDP or international shipping, this matters when planning retail price and margin.

GSM affects fabric body and stability, which can influence how a garment supports decoration. But surface finish, fiber, stretch and knit structure matter too. Dense embroidery on a light or stretchy fabric may need backing, while printing results depend strongly on the fabric face and pretreatment.

Compare the same specification: fiber content, construction, finished GSM, width, finish, stretch, shrinkage and color. Then wash both samples the same way. A heavier sample is not automatically the better sample.

State the fabric construction, fiber composition, target finished GSM, agreed tolerance, color, finish, usable width when relevant, stretch requirements and shrinkage expectations. Attach an approved swatch or reference whenever possible.

Do not assume every roll will match one exact number. Agree a tolerance with the manufacturer based on the fabric, mill capability and test method, then record it in the approved specification. The tolerance should be confirmed before bulk production.

Keeping the first collection focused can simplify sampling, purchasing and quality control. Many startups benefit from using one core T-shirt fabric and one core sweatshirt or hoodie fabric before expanding into many weights and constructions.

Yes. Long-staple fiber, clean yarn, compact knitting, good finishing, controlled shrinkage and a well-developed pattern can make a lower-GSM fabric feel refined and expensive. Premium is not a synonym for heavy.

It can be useful when the dimensions and scale are accurate. For production quality control, test multiple specimens from different parts of the roll and average the results rather than relying on one small swatch.

Use: GSM × width in metres × length in metres ÷ 1000 = net kilograms. Actual shipping weight will be higher once the tube, packaging and other materials are included.

Ask for construction, composition, target finished GSM and tolerance, finish, usable width, shrinkage, colorfastness, stretch or recovery where relevant, and an approved pre-production sample. Also confirm how the mill will handle substitutions or lot-to-lot variation.