Understanding GSM in Fabrics: What It Means and How It’s Determined

When sourcing fabrics or developing apparel — especially especially activewear, yoga wear, and performance garments — one technical term appears repeatedly: GSM.
But what exactly is GSM?
How is it calculated?
And why does it matter so much in product development, comfort, durability, and performance?

This article breaks down everything brands and designers need to know about GSM, how it is regulated, and hot to choose the right GSM for your collection.

What Is GSM?

GSM = Grams per Square Meter
It is a standardized measurement that indicates the weight or density of a fabric.

In simple terms:

• Higher GSM = thicker, denser, heavier fabric
• Lower GSM = lighter, thinner, more breathable fabric

For example:

• Lightweight yoga tops might use 160-200 GSM
• Standard leggings use 220-260 GSM
• High-support or winter leggings may use 280-350 GSM

GSM does not directly equal quality — but it does determine how the fabric performs.

How Is GSM Determined? (The Industry Standard Method)

The textile industry follows a regulated, standardized testing method–usually based on ISO, ASTM or GB/T standards — to ensure GSM measurement is accurate and consistent.

Step 1: Cut a Fabric Sample

A specific tool called a GSM Cutter is used.
It cuts a perfect circular fabric swatch of 100 cm² (10 cm x 10 cm equivalent).

Step 2: Weight the Sample

The circular fabric piece is placed on a precision digital scale, measured in grams.

Step 3: Convert to GSM

Because the swatch is 1/100 of a square meter:

GSM = Sample Weight (g) x 100

Example:
If the test swatch weights 2.5 grams, then:

GSM = 2.5 x 100 = 250 GSM

This process ensures fabric mills, brands, and manufacturers speak the same technical language, regardless of country or factory.

Why GSM Matters in Activewear & Yoga Wear

1. Opacity & Squat-Proof Performance

Women’s leggings typically require GSM 240+ to avoid transparency.
Lower GSM can fail squat tests.

2. Support & Compression

Higher GSM fabrics (260-320 GSM) offer:

• Stronger compression
• Sculpting effect
• Better elasticity retention

Perfect for performance bottoms.

3. Breathability & Comfort

Lower GSM fabrics (160-200 GSM):

• Feel cooler
• Enable airflow
• Are ideal for tops pr summer wear

4. Durability & Pilling Resistance

Higher GSM often improves:

• Abrasion resistance
• Lifespan
• Pilling performance

Especially important for activewear washed frequently.

5. Seasonal Use

• Summer active tops: 160-190 GSM
• Everyday leggings: 220-260 GSM
• Winter yoga pants / fleece-lined: 280-350 GSM

Choosing the right GSM ensures the garment matches its intended climate.

Is a Higher GSM Better?

No. Although many marketing companies will have you believe that higher GSM is better.

All else being equal, higher GSM towel have more more microfiber, and are therefore more expensive. It will also also be thicker and will absorb more total liquid.

But, there are other factors that determine the quality of a towel.

The main factor is the quality of the yarn. Secondary factors are construction of the towel. The machines that the material is woven on. The precision of the fiber “splitting” process.

Lower quality microfiber material can be made to have a higher GSM and use less microfiber material, by utilizing a thicker “base layer” of 100% polyester.

Most microfiber material is made by weaving the surface yarn through a base layer. The surface yarn is the part of the material with pile, on the outside, that you feel. The base layer is the structure that the surface layer yarn is woven through.

It is possible to make less expensive and lower quality towels that feel heavier and weigh (higher GSM) more by using a thicker base layer yarn. For example, there are some towels in which the base layer is up to 50% of the total fabric weight.

How GSM Differs Across Fiber Types

GSM is influenced by fiber density. For example:

Fabric Type	Common GSM Range	Characteristics
Nylon/Spandex	220-300	Dense, smooth, high stretch
Polyester/Spandex	180-260	Lightweight, breathable
Cotton/Spandex	180-260	Softer, thicker feel
Seamless Knits	160-250	Lighter depending on knit density
Brushed Fabrics	240-320	Warm, soft, winter-friendly

Activewear relies heavily on nylon and polyester blends because they achieve performance with lower weight.

GSM vs. Fabric Thickness: Not Always the Same

A common misconception:

“Higher GSM = thicker fabric.”

Not exactly.

Two fabrics can have:

• Same GSM but different thickness
• Same thickness but different GSM

Because:

• Fiber density varies
• Knit structure changes
• Finishes (brushed, peached) affect surface weight

Thus GSM is only one factor — brands should evaluate GSM + stretch + opacity + handfeel together.

How Brands Should Use GSM When Developing New Products

1. Define the product purpose

• Yoga: soft, stretchy, mid-GSM
• Running: lightweight, sweat-wicking
• Shapewear leggings: high GSM compression

2. Align with competitors

Benchmark bestsellers to understand market expectations.

3. Test GSM variations

Small changes (10-20 GSM) dramatically impact:

• Opacity
• COmpression
• Drape

4. Confirm with physical samples

GSM on paper is not enough-handfeel matters.

Recommended GSM Ranges for Activewear

Category	GSM Range	Notes
Yoga Tops	160-200	Lightweight, breathable
Sports Bras	200-260	Structured support
Yoga Leggings	220-260	Everyday yoga
Squat-Proof Leggings	240-300	High opacity
Compression Wear	260-320	Firm support
Winter Leggings	280-350	Thermal & brushed

Conclusion

GSM is a foundational concept in fabric selection–especially for activewear and yoga wear.
Understanding GSM helps brands breate products that align with performance needs, customer expectations, and market trends.

Whether you focus on compression leggings, soft yoga sets, or technical gym wear, choosing the right GSM ensures your garments achieve the perfect balance of:

✔ Comfort
✔ Performance
✔ Durability
✔ Functionality