If ever you’ve looked around for a new sleeping bag, the first thing you’ll notice is the ratings on them. But what do they mean? Are they regulated or calibrated in any way? And which one is going to suit you best?

The ratings system on sleeping bags has forever been a ‘guesstimate’ from the manufacturer based on the ‘average’ person, and the materials and density of the bags.

No need to throw a leg out to be comfortable anymore!

But what’s an ‘average’ person?

Bingo. The hassle is that it’s not very accurate, especially from person to person. Moreover, if you buy a sleeping bag that’s rated to -2 degrees, take it camping on a +8 degree night and still freeze, you’re not going to be impressed. Borderline waiting out front of where you bought it from at 3 in the morning ready to throw it through their window. So you do what most do, and buy the lowest rating bag you can find, and sleep one leg, one arm, three fingers and half a knee out of the bag to be comfortable.

Purchasing a new sleeping bag to take camping has just become that much simpler. With the introduction of the new ISO23537:2016 ratings for bags (which used to be EU ratings for those who have bought very high end hiking bags), things are destined to be a little more solid in their temp ratings, and your comfort ratings.


The hope is with the new calibrated rating system, all of the bag manufacturers will get on board, and take a lot of the guess work out of picking your next good nights sleep – Blackwolf are already there.

Interestingly enough, on the Blackwolf bags we got a chance to look at, their coldest rating is around the -2 degree mark, which we believe would actually be accurate. Gone are thedays of getting a -15 degree bag for a typical winters night where it’s just warm enough for +5.

Do you think the ISO rating system and introduction is a good thing? Or are you happy just getting the coldest rated bag you can and making do?