Classifications - Sleeping Bags for Camping
As with tents, the basic classification used by manufacturers relates to the number of seasons that a sleeping bag can be used in comfort by an average, fit camper.
To communicate this, manufacturers use a number of ratings - the most common being Minimum Recommended Temperature and Comfort Temperature.
Minimum Recommended Temperature is defined as the lowest temperature at which the sleeping bag is recommended for use. However, minimum really does mean minimum and use at this temperature will probably not be very enjoyable.
A more useful measure is Comfort Temperature. Comfort Temperature - as the name suggests - is the temperature at which the average camper will be comfortable enough to actually sleep!
If there's only one temperature specified, it is best to assume this is the more extreme, Minimum Recommended Temperature.
On this basis, sleeping bags are usually classified as:
- 1/2 season (comfortable down to +5 degrees Centigrade)
- 2 season (comfortable down to +1 degrees Centigrade)
- 2/3 Season (comfortable down to -2 degrees Centigrade)
- 3 Season (down to -5 degrees Centigrade)
- 4 Season (comfortable down to -7 degrees Centigrade)
The more specialist manufacturers support these claims by reference to independent testing regimes such as those developed by Leeds University or the Hohenstein Institute in Germany.
This has resulted in standards (BS4745, EN13537) that are used to compare sleeping bags. So if you want an independent assessment of performance, ask about compliance with these.
At this point it's worthwhile re-stating that the way YOU feel in a particular sleeping bag is governed by other factors such as your metabolic rate, your gender (women tend to be colder when asleep than men), your build (whether you're slim or . . er . . not so slim) whether you're using a insulating sleeping mat (always recommended) and the quality of the clothes you wear (if any) whilst you sleep.
So, view these ratings as a guide only. If you tend to feel the cold . . . then something rated as comfortable down to +1 degrees Centigrade may only be comfortable for you at +5 degrees Centigrade.
Also, bear in mind that it's easier to 'vent' a sleeping bag that's too warm than stay warm in a sleeping bag that's inadequate.
Another consideration is how you plan to use the sleeping bag
Do you plan to use it for backpacking (when compressed size and weight will be important) or for more general camping (when comfort may be paramount).