Fabric Files: Demystifying Fabric Weight

This content was originally written for Indiesew and has been adapted for this blog. It was originally published on December 12, 2017

It wasn’t until I started the Indiesew Fabric Shop, that I started to understand the intricacies of textiles. I knew of a few broad categories of fabric (chambrays, lawns, and those I referred to as simply rayons), but I didn’t understand how all of the different characteristics of fabric work together to create a wearable textile. Perhaps the most mysterious of those characteristics was fabric weight. 

Today I thought it would be useful to offer a primer on fabric weight. You may not consider fabric weight useful in your sewing hobby right now, but eventually you’ll come face to face with ordering fabric online and lacking one very vital piece of information, the per square yard/meter weight. Fabric weight is just one piece of the entire makeup of a fabric, but an incredibly useful one.

Fabric Weight Defined

Fabric weight is generally listed in the US as ounces per square yard and in many other countries as grams per square meter (GSM). Sometimes in the US, you'll see fabric weights listed as just ounces (for example, a 10-ounce French terry or a 6-ounce cotton shirting). It can be assumed that this is the weight of the fabric per square yard.

This is the standardized way of listing fabric weights because fabric can come in a wide range of widths from the manufacturer. Thus, fabric is weighed on a scale as a 36” by 36” square, or a formula is used to find that value based on a different size of fabric.

The per square yard/meter weight of the fabric only tells us how much the fabric weighs. It doesn’t indicate how loose or dense the weave or knit is. And it varies widely depending on the type of fiber that is used to create the fabric.

Why is fabric weight important?

In many sewing patterns, designers will list a suitable fabric weight for the garment. This information is important to note. For example, sewing the Lonetree Jacket in a 10-ounce canvas (the pink version) gives the jacket a very different look than the 7-ounce Tencel twill Lonetree vest (the green version).

Generally, the less a fabric weighs, the more pliable and drapey it will be, and the more it will breathe in hot weather. Also, the lighter a fabric is, the more sheer or see-through it may appear. For reference, fabrics that weigh less than 2-ounces per square yard will generally be somewhat sheer. Once in the 4-ounce range and above, a fabric tends to be less see-through.

The heavier a fabric is, the more durable it will be to wearing and washing. This is particularly true of twill weave fabrics like denim (shown below). Heavier fabrics are generally more opaque, rarely needing a lining for skirts and dresses.

But these are not hard and fast rules. Many lawns and chambray can be very lightweight, but have a stiffer appearance due to the fiber content. Rayon and Tencel twills often have a beautiful heavy drape, but weigh anywhere from 6 to 8 ounces per yard.

It’s important to consider the entire list of characteristics when choosing a fabric, something that you will naturally start to do as you sew more. You’ll eventually learn that cotton twills are stiffer than rayon or Tencel twill. You’ll learn that cotton voile and rayon voile have a completely different hand.  

Fabric Weight Quick Reference

But as a general reference, here’s a quick guide of fabric weights for the most commonly found fabrics:

Garment Types by General Fabric Weight

Here's a very general guideline for garment types and fabric weight recommendations. But take this with a grain of salt, as some garments will look great in many different fabric types:

Do I need to calculate fabric weight at home?

Previously, we offered a spreadsheet for sewists to calculate the weight of their fabric at home. But after many years of observing how people used that tool, we realized that fabric weight isn't really that important once you get the fabric into your hands.

Fabric weight is a great data point when purchasing fabric online and can give you an idea of the hand and pliability of the fabric without seeing it in person. But once you're able to touch the fabric, you'll be able to easily tell if it's well suited for a sewing project.

I hope this helps demystify fabric weights! We want you to feel comfortable know how fabric weights affect drape, opacity, and durability, but also encourage you to consider other factors like fiber content and weave type. Our Fabric Files series contains super detailed blog posts on a specific type of fabric. Be sure to give those a read for a particular substrate.

Happy sewing!