Doesn't add 25 degrees

By: Barry Robertson - Sea to Summit February 10, 2011

G'Day, Sheri - As I mentioned in a previous comment on this page, there are a number of factors which make it difficult to give a precise rating to a thermal liner. Chief among these is the fact that different people sleep either 'warmer' or 'colder' - I'm a warm sleeper, and if I'm speaking with a 'cold' sleeper, I'll tailor product recommendations accordingly. In your case, it may be that a '+15°F' rating is more appropriate for this liner. A second factor which makes this process difficult is the imprecise nature of sleeping bag temperature ratings. There is no mandated standard for temperature ratings in the US (although the European EN rating system is becoming more common), and some bags have somewhat unrealistic numbers embroidered on them. Significantly, the EN rating differentiates between thermal performance for a man and a woman *for the same bag* - part of that 'warm or cold sleeper' concept mentioned above. Another factor often overlooked is the insulative properties of the sleeping pad, which becomes more significant below 30°F as the ground freezes (and may therefore be colder than the ambient air temperature). The 'R' value is key here. I'd be happy to provide more details if you'd like to email me directly at barry@seatosummit.com Cheers Barry Robertson Customer Relations Manager

Helpful Votes: 0 Yes