What is this mysterious GSM?
GSM= grams per square meter of fabric.
You have probably heard about this many times when browsing the Internet for the perfect sling/wrap. But what is it actually, and is it at all useful? How can you calculate it?
The GSM informs you how much yarn (in grams) the weaver has used to create your sling/wrap.
If you want to compare two cotton slings made with the same weaving pattern, then the GSM is very useful. The one that has a highest GSM will be thicker than the one with the lowest GSM.
If you look inside your closet and find the pile of t-shirts then your thinnest cotton t-shirt will properly have a GSM around 150 and your thickest t-shirt (the one you stole from your boyfriend’s closet) will have a GSM of approximately 220.
If you want to compare a cotton sling and a cashmere sling (with the same weave) then the GSM is not very useful, because different materials have different weight. This means that the two slings will not have the same thickness even though they have the same weave and the same GSM.
There’s the same problem if you want to compare two cotton sling that has the same GSM but different weaves. A 300gsm cotton sling can feel really thick and floppy in a loose weave, but hard and stiff in a tight weave.
So the conclusion is that the GSM can give you a hint about the thickness, but only a hint.
This is how you calculate the GSM:
Weight in grams/(length in meters x width in meters)
You need to measure your wrap in hand, using a soft tape.
First you multiply the length in metres by the width in metres.
Then you divide the weight in grams by this result you got.
This shows you the GSM of your wrap.
Remember to deduct the weight of the rings (approx. 50g) and include the fold around the rings in the length.
If your sling/wrap has fringes, this area will be lighter than the rest of the fabric, because there is no weft thread in this place.
When you sling/wrap is washed the fabric will shrink a little bit, this will increase the GSM.
To make it easier for you, we made a calculator where you can calculate the GSM: