Gear Review: Big Agnes McAlpin SL Winter Bag

Big Agnes McAlpin SL winter sleeping bag
Big Agnes McAlpin SL winter bag

Sleeping Bag
Big Agnes McAlpin SL (5° F)
$360, $380 long, 2 lbs. 14 oz. (reg)
Sizes: regular and long

What should you look for in a winter sleeping bag? I want it to be warm enough, sure, but I also look for several other attributes, like a little extra space, resilience to moisture, and that it’s not too heavy or bulky and doesn’t cost more than my winter tent. Big Agnes has answered my demands with the McAlpin.

Sleeping out under the stars (without a tent) for three straight clear, frosty, mid-January nights in Idaho’s Boise Mountains, I stayed plenty warm enough in temperatures that dropped into the teens. (Sleeping on an insulated air mattress, I wore only base layers and sometimes a hat, and at other times loosened the hood and collar because I was so warm.) I think this bag is true to its 5° F rating (EN lower limit for men), in part thanks to a fat draft tube and collar and baffles that prevent down from shifting. The 700-fill down (28 oz. of it in the regular size, 31 oz. in the long) is of high enough quality to keep the bag a lightweight in this category (under three pounds) and compact (8×17.5 inches in its stuff sack for the regular). The bag has good space (60 inches of shoulder girth, 54 inches in the hips, 36 inches at the feet in the regular, 62, 56, 38 in the long), yet is contoured so that the hood closes tightly around my face.

Winter bags are more susceptible to moisture simply from condensation, and have traditionally combated this through using a water-resistant shell. But the McAlpin employs new, water-resistant DownTek down, which repels moisture and helps the down dry faster once wet. (I’ve also reviewed the Sierra Designs Zissou 15 bag, which uses that company’s proprietary DriDown, a similar product.) While the shell around the hood and chest area of the bag got damp with condensation from my breath every night, there was no effect on the bag’s loft or warmth. By comparison, my son’s traditional down bag was much wetter, compromising its loft (but fortunately he’s young and tough).

The McAlpin also sports a full-length zipper, a taffeta lining and nylon ripstop shell that are breathable and down-resistant, and a water-resistant treatment on the shell fabric, as well as interior fabric loops for a sleeping bag liner. It’s rare to find this much comfort and quality, and such a low weight, at a competitive price.

Big Agnes does not offer a women’s version of the McAlpin, but the company makes women’s bags with DownTek, including the Women’s Lithia Spring SL 15°, $350 (petite) and $380 (regular).

For more reviews of my favorite sleeping bags, type the words “sleeping bags” into the Search box at left. See also my Pro Tips articles “How to Choose a Sleeping Bag” and “Staying Warm in a Sleeping Bag.”

NOTE: I’ve been testing gear for Backpacker Magazine for 20 years. At The Big Outside, I review only what I consider the best outdoor gear and apparel. See all of my reviews by clicking on the Gear Reviews category at left or in the main menu. See more reviews of backpacking gear I like by clicking on the “backpacking gear reviews” tag in the tag cloud in the left sidebar.

—Michael Lanza



Key Ingredient to Family Yurt Trip: What’s Missing

Gear Review: Outdoor Research Luminary Gloves


Leave a Comment