What Does Weight of Fabric Mean?

Weight of fabric is the mass of a textile over a specific area — as in 2-D space, length-times-width area. In plain language, it’s how much one square yard or one square meter of fabric weighs when you drop it on a scale.

Factors that impact fabric weight include:

• Thickness of yarns that make up the material.
• How tightly the fabric is woven or knitted.
• The fiber (i.e., wool, silk, nylon, etc.) of which the textile is made.

If you’ve sewn for any amount of time, you know that a square of denim is heavier than a square of cotton jersey. But what does that REALLY mean for sewists?

In this article, you will learn why fabric weight matters in sewing clothes and how fabric weight is calculated. Plus, there are tables with the weights of popular fabrics for garment sewing for easy reference. TABLES, guys — get stoked!

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Why is Fabric Weight Important?

As a sewist, it’s to your benefit to understand fabric weight. The top three reasons why fabric weight is important are (in no particular order): 

1.) Fabric weight is a shorthand for how to use a fabric.

A fabric labeled “lightweight” could be good for tops. A fabric labeled “heavyweight” could be good for bottoms and outerwear. And mid-weight fabric could be good for tops OR bottoms. You obviously need to check your sewing pattern for fabric recommendations. But, fabric weight can be a first filter when choosing a fabric for a project.

2.) Fabric weight can reveal lifespan.

A heavyweight fabric — for example, denim — likely will stand up to more wear, tear, and laundering vs. a lightweight fabric — for example, chiffon. If you have to choose between two similar fabrics for the same project, the option with the greater fabric weight probably will make a garment that lasts longer.

3.) Fabric weight impacts the look of a garment.

Fabric is made of yarn, and fabric weight is a reflection of the thickness of that yarn. In general, lighter-weight fabrics are more flexible, fluid, and easier to fold than heavier-weight fabrics. Thinner sticks are easier to bend vs. thicker sticks, right? It’s similar to thin and thick yarns. Thick yarns make fabrics that provide structure to garments, because heavier-weight fabrics (often) stay in place when released.

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How Do You Calculate the Weight of Fabric?

As mentioned, the thickness of yarn that composes a fabric determines a fabric’s weight. The thicker the yarn, the heavier the fabric.

The density of a weave or knit also impacts fabric weight. A loose weave or knit creates a fabric with more open spaces (e.g., mesh, gauze), and open spaces don’t have mass. (A fabric with more open spaces also will be more sheer and breathable.)

Fabric weight is measured in either ounces per square yard (oz/yd²) or grams per square meter (gsm). Fabric weight in ounces vs. fabric weight in grams depends on where you are in the world and who’s selling you the fabric. Pro tip: If you’re buying fabric in a unit that’s unfamiliar to you, do a web search for “convert grams per square meter to ounces per square yard” (or vice versa). I PROMISE you’ll find a calculator!

The mass units give away how fabric weight is calculated: by weighing one square yard (a piece of fabric 36-by-36 inches) or one square meter (a piece of fabric 100-by-100 centimeters). If you were so inclined, you could cut a square yard or square meter of fabric and weigh it on a kitchen scale.

Fabric Weights for Sewing Clothes

You know WHY fabric weight matters to sewists, and HOW fabric weight is calculated. Now, let’s get into some practical application — the fabric weights of popular garment textiles.

Lightweight fabric for sewing (sometimes called top weight) is best for sewing projects that don’t need to stand up to a lot of use, abuse, and laundering. For example, a rayon blouse is better for office work than yard work.

Heavyweight fabric (sometimes called bottom weight) is best for the bottom half of your body and outerwear. This fabric does a good job protecting your person from the outside environment, whether that’s wind or a rough park bench.

Medium-weight fabric is between lightweight and heavyweight. It’s more robust than lightweight fabric but not as sturdy as heavyweight fabric.

Sewists who have a good handle on fabric weights don’t waste time and money on stitching mismatched fabrics and patterns. That’s because they don’t ask a fabric to be something that it’s not.

This is a skill that develops over time, so don’t get discouraged if you’re a newbie who’s made poor fabric choices (we’ve ALL been there!). A good place to get a fabric-weight education is to check out pattern hashtags on Instagram to see what works — and what doesn’t.

Common Garments by Fabric Weight

The following garments are some of the most-searched on the internet when it comes to fabric weight. So, if you’re fixing to sew one of these garments (or something similar) here’s where to start in terms of fabric weight.

The right fabric makes a garment — and the wrong fabric surely breaks it. And, fabric weight is an important factor in whether your me-made clothes fly or flop. With hope this little guide gives you more confidence in analyzing fabrics by their weight.

Over to you: How often do you look at fabric weight when you choose fabric? TBH, I’m probably 50-50 on checking weight (but I’ve been sewing for awhile and have a decent handle on fabric weight at this point). There are certain projects where I’m particular about fabric weight — sewing jeans, for instance. I like stretch denim that’s at least 9-10 oz/yd².