Extreme rating
The extreme rating is the lowest of the temperature figures a sleeping bag label may show. It describes an emergency rather than a comfortable night, so never plan a trip around it.
Where you'll see it
It sits beside the comfort and limit ratings on labels and product pages. Its place on the label is not a sign that it is the figure to use. Read it as an emergency figure, and compare bags by their comfort rating instead.
What to check
- Which figure is labelled extreme, so you do not mistake it for the comfort rating.
- The maker's explanation of the three figures, if one is published.
- The comfort rating, which is the figure to compare with your forecast low.
- The forecast for the site itself, since a clear, still night in a valley can be colder than the nearest town.
Related terms
- Comfort rating: the figure to compare bags by.
- Limit rating: the figure for someone who sleeps warm.
- EN ISO 23537: the standard method makers use to state these figures.
Read more: sleeping bag temperature ratings explained and, if one fits, the sleeping bag rating calculator.