# GSM (grams per square metre) — Laundry Care Symbol | Launderwise

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Fabric & materials

# GSM (grams per square metre)

A measure of fabric weight expressed as grams per square metre, used to compare how heavy, dense or substantial a textile is.

## What it means

GSM tells you the mass of one square metre of the fabric. A higher GSM means a denser, heavier and usually warmer or more durable cloth; a lower GSM means a lighter, more breathable one. It is the standard way towels, sheets and T-shirts are graded.

## What to do

Use GSM to set expectations: a 600+ GSM towel is plush but slow to dry, while a 400 GSM towel dries faster. Heavier fabrics generally need a longer drying time and benefit from not being overpacked in the drum.

## How to use this term

Use this fabric-care term to understand why the same detergent, heat or stain method can behave differently across fibres.

- Read gsm (grams per square metre) with the other symbols on the same care label; the strictest symbol wins.
- Match the instruction to the garment's most fragile part, including trims, lining, prints and finishes.
- If the label, fabric behaviour and stain method disagree, test a hidden area or choose the lower-risk route.

### Common mistake

Do not choose a method only by stain type; fibre, weave, dye and finish can change what is safe.

For the broader method, use the [Beginner laundry guide ](/blog/getting-started-laundry/index.md)and then return to this term when the label changes the safe option.

## Related terms

- [Delicates](/glossary/delicates/index.md)
- [Tumble dry, high heat](/glossary/tumble-dry-high/index.md)
- [Sorting laundry](/glossary/sorting-laundry/index.md)

## Sources

- [ISO 3801 Textiles — Determination of mass per unit length and mass per unit area ](https://www.iso.org/standard/9335.html)— International Organization for Standardization

[ Back to the full glossary](/glossary/index.md)