Posted 15 April 2016

There are three ways of temperature testing sleeping bags

  1. EN13537 or
  2. ISO (independent Organisation for Standardisation) or
  3. BSI (British Standards Institute)

All produce very similar results for a comfort temperature but other criteria differ.

The point to keep in mind is that the number quoted is just that, a number. It is not a guarantee of performance.

You should use the result to illustrate the difference in performance; so for bags tested the same way a comfort temperature of minus 10 is warmer than a comfort temperature of minus 5 but colder than a comfort temperature of minus 20.

Perception of temperature

Your next headache is how we perceive temperature.

Take the following examples;

  • minus 10 in a very dry climate feels warmer than minus 10 in a damp humid climate
  • minus 10 at sea level feels warmer than minus 10 at 1000m altitude
  • minus 10 in a mountain tent feels warmer than minus 10 in warehouse
  • minus 10 in still air is warmer than minus 10 in a 50km/h wind

But also;

Different people have different metabolic rates and feel temperature differently.

If you want to know more about the effects of height, humidity and wind chill check the internet for local information or where you intend to explore or use a sleeping bag.

In the UK this information is available at: http://www.mountainsafety.co.uk/Weather-Wind-Chill.aspx

In the US the information is here: http://www.nws.noaa.gov/om/winter/windchill.shtml

Our final thoughts

We would always suggest that you buy a sleeping bag that is a little warmer than you expect to need. If you are too cold all you can do is put on some thermals and HOPE!

If you are too warm you can unzip the sleeping bag from the bottom and stick your feet out. Or you can slacken the neck collar or take off some clothes. In other words - several options that are better than feeling cold!

It is all about managing your own expectations.

We supply people going to the North and South Poles with minus 40 expedition sleeping bags and so far they have all been happy!

When buying a sleeping bag you should discuss your needs by either sending us an email or talking to an expert in your chosen outdoor shop.

We hope you enjoy the outdoors wherever you go.