Over eight backpacking seasons, we have spent countless nights sleeping on the ground outside. We took these bags backpacking in the mountains and deserts, and on many nights of car camping. We tested the limits of these bags' warmth, spending cold nights in the alpine where temperatures went below freezing, out in snow and thunderstorms, and spent some very warm nights at low elevations and climbing destinations.
Spending many nights at high elevation in the mountains, early spring through late fall, we were able to test each sleeping bag's warmth. We evaluated each bag's fill materials for quality and amount as well as the fit and features like baffles and shape to determine the warmest of the bunch.
We weighed all the bags - which one was the lightest? Which was the heaviest? Which had the best warmth to weight ratio that made it worth it to carry around with us?
Which bag was the softest, cushiest cloud we could sleep in, and which had the roughest materials? Were they too big, too small or just right?
What bag had the most compressible materials? Did they come with a compression sack to squeeze them down to the smallest possible package? Size does matter in this metric.
Some features just added weight but weren't that useful. Others were essential to the bag's functionality. We used them all and evaluated their worthiness.
We stuffed, compressed, packed up, and carried all of these bags for several outdoor adventures and then zipped, unzipped, toggled, and of course, slept in these bags to test them to the fullest.