Sleeping bags come in all sorts of shapes and sizes and the range (and price range) can be very confusing. So when trying to choose what sleeping bag to buy, it's worth starting from basics, and asking yourself what temperature range you want it to cover.
A very rough guide to the approximate use you might expect from a sleeping bag is given by the use of season ratings. These indicate the temperatures at which a sleeping bag should keep you comfortable if camping outside using a tent or bivibag and a reasonable mat for the conditions. We have recently revamped our season ratings to bring them in to line with other retailers. This is just a guide - you will know if you feel the cold or not so buy a bag accordingly!
| Rating |
Seasons |
Approximate Temperature |
| 1 |
UK Mid Summer and Warmer |
+10ºC and above |
| 2 |
UK Late Spring to Early Autumn |
+5ºC to +10ºC |
| 3 |
UK Spring or Autumn |
0ºC to +5ºC |
| 4 |
UK Winter |
-5ºC to 0ºC |
| 5 |
Sub 5000m Expedition |
-10ºC to -5ºC |
| 5+ |
High Altitude/Polar |
below -10ºC |
Having worked out the temperature rating of the bag you want you then need to choose between down and synthetic filling. The latter is cheaper and can be dried out easily if it gets wet. However it is heavier and bulkier for the equivalent level of warmth. Good quality down will last twice as long as synthetic fibre if it is looked after properly and remains the main choice for most serious mountaineering use (though not for multiday aid routes in Yosemite where violent storms can mean down bags becoming soaked and useless very rapidly).