So the time has come for you to put your hand in your pocket and buy a new sleeping bag. You head online, or to the shop if you’re old-school like that, with the money ready to upgrade your sleep system. But with so much choice and so many different options, how do you know what is best for you? Well, it’s my job today to break that down and make your purchase a more informed, more enjoyable experience.
So where to start? Well, the first factor to consider is when you will most likely be using your new sleeping bag. A winter bag with an extreme rating of -40 degrees is probably going to be overkill if you are camping in the UK over Spring/Summer. Likewise, you wouldn’t want to take a quilt on an expedition through the Himalayas.
And that’s where comfort ratings come in. Although not a legal requirement, most reputable brands will test their sleeping bags using the EN-ISO 23537, basically a measure of how each bag would perform in different temperatures. These comfort ratings are broken down into three sections:
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The Comfort Rating - Indicates the minimum temperature an individual can sleep in a relaxed position and get a good nights sleep.
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The Limit of Control Rating - Indicates the lowest temperature where a person who is curled up and fighting against the cold can sleep through the night.
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The Extreme Rating - For emergency scenarios only. The minimum temperature where a person can remain in the sleeping bag for upto 6-hours in a curled position while really fighting against the cold.
‘But how is this tested?’ I hear you ask. Well, this is where it gets a bit techy. The test is conducted using a thermal mannequin that is placed in the sleeping bag on a standard foam roll mat. The test then takes a series of measurements to test how insulating the sleeping bag is, before determining the overall comfort ratings which you will see on most sleeping bags.
However, these are lab tests, not field tests and should be taken with a pinch of salt. It is extremely difficult to replicate real world conditions such as wind and rain, along with different elements of your set-up, such as your sleeping pad.
Now that the science is out of the way, what comfort rating do you actually want for UK seasons? Having had our fair share of nights in the mountains, our pro tip would be to opt a couple of degrees colder than the temperatures you are expecting to use it in (you will be thanking me for this one day). We would recommend the following as a rule of thumb:
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Spring: - 2 degrees celsius
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Summer: 0 degrees celsius
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Autumn: -5 degrees celsius
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Winter: -15 degrees celsius
And that’s it really. That’s sleeping bag comfort ratings made easy.
Over and Out.