Search:

Just remember that is the extreme survival rating and that comfort for male adult would be around -10 to -16 and as long as you got some insulation you will be toasty warm. Nothing like not having to...

C = 1/2 x (F - 30)
Looks strange when you look at it but maths never lies!
Mine is rated to -32 also (kathmandu moonraker) and I almost had to put both legs in it on a cold night the other week....