Knit Fabric 101: Understanding GSM and Fabric Types for Your Next Loungewear Collection

Sourcing knit fabrics? Learn about GSM, French Terry, Rib, and Interlock to choose the best materials for your brand. Expert insights from SML Intimate.

Have you ever ordered a sample of a hoodie that looked thick and cozy in photos, only to have it arrive feeling thin and flimsy? Or perhaps you’ve bought pajamas that lost their shape after just two washes?

In the world of women’s loungewear and knitwear, the "feel" of the fabric isn't just about luck—it’s about two technical factors: Fabric Typeand GSM.

Whether you are a brand owner looking to source the best materials or a shopper who wants to know what they’re paying for, this guide will break down everything you need to know about knit fabrics.

Part 1: What is GSM and Why Should You Care?

If you’ve spent any time looking at fabric specs, you’ve seen the term GSM. It stands for Grams per Square Meter.

Simply put, GSM measures the weight and density of the fabric. Think of it like the "thickness" gauge. A higher GSM usually means a thicker, heavier fabric, while a lower GSM means something light and airy.

Why GSM matters for your clothing:

Transparency:Low GSM white fabrics can be "see-through," which is usually a deal-breaker for leggings or joggers.

Durability:Generally, higher GSM fabrics hold their shape better over time.

Seasonality:You wouldn't want a 400 GSM fabric for a summer tank top, just like you wouldn't want a 140 GSM fabric for winter sweatpants.

A Quick Cheat Sheet for Loungewear:

120 - 150 GSM:Lightweight. Perfect for basic T-shirts, camisoles, and summer-weight pajamas.

160 - 220 GSM:Medium weight. This is the "sweet spot" for high-quality T-shirts and lightweight loungewear sets.

250 - 350 GSM:Heavyweight. Ideal for hoodies, sweatshirts, and joggers. This weight gives that "premium," structured look.

Part 2: Common Knit Fabrics in Women’s Loungewear

Knowing the weight (GSM) is only half the battle. The waythe fabric is knitted determines its texture, stretch, and how it drapes on the body. Here are the most popular choices we use at SML Intimate:

1. Single Jersey (The All-Rounder)

This is the most common knit fabric. It’s smooth on one side and has slight loops on the other.

Best for:T-shirts, lightweight pajamas, and tank tops.

Why we love it:It’s breathable and has a natural stretch that feels like a second skin.

2. French Terry (The Hoodie King)

You’ll recognize French Terry by the "loops" on the inside and the smooth surface on the outside. It’s heavier than jersey but lighter than true fleece.

Best for:Hoodies, sweatshirts, and casual joggers.

Why we love it:It’s moisture-wicking and cozy without being overly hot. It’s the gold standard for "athleisure."

3. Rib Knit (The Flattering Stretch)

Rib knit has visible vertical lines (ribs). Because of this structure, it has much more "give" and elasticity than jersey.

Best for:Form-fitting tops, cardigans, and cuffs/necklines.

Why we love it:It hugs the body beautifully and adds a premium, textured look to even the simplest designs.

4. Interlock (The Premium Choice)

Interlock is a double-knit fabric, meaning it looks the same on both sides. It’s thicker and more stable than jersey.

Best for:High-end loungewear, soft robes, and leggings.

Why we love it:It doesn't curl at the edges and feels much more substantial and "expensive" to the touch.

Part 3: How to Match Fabric to Product

Choosing the right combination is where the magic happens. At SML Intimate, we’ve spent years perfecting these pairings. Here are a few of our "pro-tips":

For a Summer Pajama Set:Go for a 140-160 GSM Cotton/Modals Jersey. It’s silky, light, and won't make you sweat at night.

For an "Oversized" Streetwear Hoodie:You want a 320-400 GSM French Terry. The weight is what gives the hoodie that iconic "boxy" shape.

For Yoga or Active Pants:Look for a 280 GSM Nylon/Spandex blend. You need the weight for coverage (no "squat-test" fails!) and the spandex for movement.

Final Thoughts

Understanding fabric isn't just for manufacturers—it’s for anyone who values quality. When you know the difference between a 180 GSM Jersey and a 300 GSM French Terry, you can make better purchasing decisions and build a wardrobe (or a brand) that lasts.

Still not sure which fabric is right for your next project?

At SML Intimate, we specialize in high-quality knitwear, from cozy pajamas to structured hoodies. We’d love to help you find the perfect match.

[Contact our team today to request a fabric swatch book!]