Fabric Weight Explained: GSM, Ounces, and Linear Yards

Today I want to talk about something that can be a little confusing: fabric weight—how to understand it and how to know what you're buying. Scroll to the bottom to listen to the video.

We’re going to cover:

• GSM (grams per square meter)

• Ounces per square yard

• Ounces per linear yard

• What these terms mean and how to compare them

  
  

Understanding these helps ensure that when you buy fabric—especially online—you get exactly the weight you need with no surprises when it arrives.

A couple of weeks ago I made a video/blog post with 9 Tips for Ordering Fabric Online. One of those tips was to pay attention to GSM, and today we’re going deeper into exactly what that means.

Why Fabric Weight Matters—Especially for Knits

With woven fabrics, the name often gives you a clue about weight. A lawn is always lightweight. A batiste is lightweight. But in the world of knits, “jersey” might be tissue thin or sweater-weight, and everything in between. So you really need the weight of the fabric to know what you’re buying.

GSM (Grams per Square Meter)

GSM is the simplest and clearest measurement. It tells you the weight of a square of fabric that is 1 meter by 1 meter, measured in grams.

Because the area is always the same, GSM lets you compare fabrics easily and accurately.

My preferred range: For pleating and smocking knit fabrics, I love working with 175–220 GSM. That’s the “sweet spot.” Most cotton/spandex jerseys fall here and many interlocks do as well But Some interlocks are heavier—up to 300 GSM. I once had a student using a 300 GSM interlock—she was breaking pleater needles, and the fabric wouldn’t pleat nicely. It was simply too heavy, something we didn’t realize until troubleshooting. Knowing the GSM from the start prevents problems like this.

Ounces per Square Yard

Sometimes fabric weight is listed in ounces per square yard, which is similar to GSM but uses a yard instead of a meter. It refers to a piece of fabric 1 yard by 1 yard weighed in ounces. Converting between GSM and oz/yd² is simple—you can Google it, and I also include a full chart in my Enjoying the World of Knits book so it is right there for you.

The Tricky One: Ounces per Linear Yard

Here’s where things get confusing. Sometimes the weight is listed as ounces per linear yard. This is not the same as ounces per square yard.

A linear yard measures:

• 1 yard in length by

• The full width of the fabric bolt (42", 45", 55", 60", 63", etc.)

Because widths vary, this measurement isn’t standardized, which makes comparisons tricky. If the listing doesn’t explicitly say “square yard” or doesn’t include the little squared symbol (yd²), it’s often referring to linear yard.

How to Convert Ounces per Linear Yard to Ounces per Square Yard

Use this formula:

(ounces per linear yard × 36) ÷ fabric width = ounces per square yard

Once you have that number, you can compare it to GSM or to other fabrics you’re familiar with.

Track Fabric Weights With a Swatch Book

If you haven't grabbed it yet, I offer a free downloadable PDF swatch book. It helps you track:

• Where a fabric came from

• Its GSM or weight

• Fiber content

• What you used it for

• How it performed

Over time you’ll build a personalized reference that makes shopping—especially online—so much easier. For example:If you made a lovely dress for your granddaughter from a 220 GSM cotton jersey, recording that means that a year later, when you want something similar, you’ll know exactly what weight worked well. You won’t accidentally choose a 160 GSM knit, which would behave very differently.

Wrap-Up

I hope this helps clarify the differences between GSM, ounces per square yard, and ounces per linear yard.

Grab the free swatch book below, and you’ll also check out the Enjoying the World of Knits if you’d like a more in-depth guide to understanding knit fabrics.

Happy sewing!