You will have noticed most sleeping bag manufacturers rate their sleeping bags as 2, 3 or 4 plus seasons. While some use GSM as their rating, if you want to know what does 400GSM mean, or any other GSM rating then read on as I explain.
What Does GSM Mean with Sleeping Bags?
GSM stands for Grams per Square Meter. So, the higher the number, the more weight there is per square meter.
This means more fabric, filling, etc, keeping you warmer. So the higher the GSM rating of your sleeping bag, the warmer you should be.
There are some exceptions to the rule however. The GSM doesn’t tell you anything about what materials are used, so you need to look at the material of the sleeping bag as well.
What Do Sleeping Bag Season Ratings Mean?
If the sleeping bags you’re looking at only have season ratings, here is what these mean:
|Season ||Suitable For ||Temperature Range
|Summer||Summer Camping ||+35 Degrees and above
|3-Season||Spring/Autumn Camping||10 - 35 Degrees
|Winter ||Winter Camping||+10 Degrees and below
These standards were brought in to make choosing the right sleeping bag for your needs straightforward and easy.
The problem, however, is that everyone has different requirements, camp in different climates, and they are are a little vague.
The temperatures the bags are designed to deal with are a better indication. Combined with the GSM to give you a good idea of the weight and density you can make a well informed decision without even seeing or feeling the sleeping bag.