What GSM should you choose for a cotton or canvas bag?

GSM stands for grams per square metre. Cut a piece of fabric one metre by one metre, put it on a scale, and the number you read is its GSM. A 140 GSM cotton weighs 140 grams per square metre. A 270 GSM canvas weighs almost twice as much.

That's it. That is the whole definition. What it doesn't tell you is how strong the bag will be, and this is where a lot of buyers get caught.

In this guide: Heavier fabric, stronger bag? Usually, not always · Ounces, if your buyer is in the USA · So which GSM for your bag? · How to check GSM yourself · One honest tip · Questions buyers ask us

Heavier fabric, stronger bag? Usually, not always

Higher GSM usually means a firmer fabric that holds its shape, feels more expensive and costs more. But strength also depends on how the fabric is woven and how the bag is stitched. A well-made 160 GSM tote with reinforced handle joints can outlast a 220 GSM bag with a single line of stitching where the handle meets the body.

So when you compare two quotes, don't compare GSM alone. Ask how the handles are attached too.

Ounces, if your buyer is in the USA

American buyers often describe canvas in ounces per square yard. One ounce per square yard is about 34 GSM. A rough conversion table:

There's no official line where cotton becomes canvas. In the bag trade, cotton from about 8 oz (around 270 GSM) is commonly sold as canvas.

So which GSM for your bag?

Start with what the bag has to do, not with a number.

A giveaway at an event

Light cotton, for example 140 GSM. It folds small, prints sharply and keeps the cost per bag down when you need thousands. People use it for a conference and then for groceries, and that's fine.

A tote you sell or give to good customers

Mid-weight, 160 GSM and up, or a light canvas. It feels like a product, not a freebie. Worth it if your logo is going to be carried around for years.

A grocery bag that carries bottles

Canvas (around 8 oz and heavier), a gusset, and strong handles with box-and-cross stitching at the joints. Here the weight earns its money.

A shopping bag for a fashion store

Heavier canvas holds a crisp shape on a shelf and in photos. Some brands choose it mostly for the look, which is a fair reason.

How to check GSM yourself

If you have a fabric swatch or a sample bag, you can check the GSM at home with a kitchen scale that reads to 0.1 g.

1. Cut a square exactly 10 cm × 10 cm from a flat part of the fabric (not a seam).
2. Weigh it.
3. Multiply by 100. A 1.6 g square is 160 GSM.

Mills use a round GSM cutter that cuts exactly 100 cm² every time. Your result will be close, not perfect, and that's normal for natural fibres.

One honest tip

If you are unsure between two weights, order the sample in the lighter one and hold it. Put the things in it that your customers will carry. Quite often the lighter fabric does the job, and then you save the difference on every single bag. We make GSM to your requirement, subject to fabric availability, so it's your choice either way.

A small confession: we'd rather talk a buyer down to a lighter, cheaper GSM that actually fits their use than sell them the heaviest canvas we stock. It costs us a bit on the order, but it's the bag that gets reordered next year, not the one that sits in a cupboard because it felt too stiff for everyday carry.

Questions buyers ask us