Big Agnes Sidney Sleeping Bag SL 25 (petite) Review

Big Agnes Sidney sleeping bag

The Big Agnes Sidney sleeping bag hits the mark for me. It’s light weight (not ultra light) and it keeps me warm. These are pretty important details for me.

(I know you really came here to read about Steve’s 2021 hike. But he’s hiking right now and will update as soon as he gets service again. In the meantime, I’ll throw in some gear reviews, which we’ve been meaning to do…forever! Thanks, Noelle)

Technical Specs

  • Temperature Rating 25 degrees F, -4 degrees C
  • Weight
    • Petite 2 lb. 1 oz.
    • Regular 2 lb. 3 oz.
  • Shell – Ripstop nylon
  • Linning – Nylon taffeta
  • Zipper location – Right
  • Insulation type – 650-fill DownTek down (Water-resistant)
  • Fill Weight
    • Petite 19 oz.
    • Regular 21 oz.
  • Fits up to 70 inches
  • Shoulder girth 55 inches
  • Hip Girth 56 inches
  • Stuff sack Size 7.5 X 15 inches
  • Compressed size
    • Petite 5.5” x 8”
    • Regular 6.5” x 8”
  • Bag size
    • Petite up to 5’5” (I’m 5’4”)
    • Regular up to 5’10”
  • Regular Price (at time of my purchase) $299.95

Features (& my thoughts about them) of the Big Agnes Sidney Sleeping Bag

Cinch system

The Big Agnes Sidney has a customizable cinch system that allows you to dial in the fit to trap more heat closer to the body and keep you warmer. It absolutely does just that! The only time this bag wasn’t warm enough was in the San Jacinto Mountains on the Pacific Crest Trail. We’d come off Fuller Ridge late in the afternoon, when the snow was slushy and I’d fallen/slid down the mountainside several times. I got wet and stayed super cold, even after changing to dry clothes. The temperature was definitely down in the low 20s, so right at the limit of this bag, and I may have been in a little shock from said mountainside sliding. Ha!

Other nights, when I wasn’t freezing before crawling into the bag, I stayed warm and cozy. There are three external clips on each side of the sleeping bag and two more at the bottom. The idea is that it cinches down the sides and the footbox to your exact size and needs, so you stay warmer.

Down filling

The fill is DownTek water repellent down. It repels water while maintaining its insulating value. I can say that we did get wet quite a few times during my 400 miles on the PCT. Rain all night long means some of it is coming in the tent, no matter how many channels you dig around it! I woke up on several occasions with parts of my pad and sleeping bag wet, but I still felt warm and dry. We’d usually pack up, start hiking and when the sun finally came out, we’d stop for a break and hang all our gear on trees and rocks. This sleeping bag dried quickly. The specs say it provides anti-microbial and anti-bacterial protection. It also says the bag absorbs 30% less water and dries 60% faster, although it doesn’t say what that’s in comparison to.

Read about our Pacific Crest Trail Hike here!

Sustainability of Big Agnes Sidney sleeping bag

Big Agnes is committed to using sustainable products, wherever and whenever possible, including using only down that comes from duck & geese that were treated ethically. Big Agnes has committed to the “Responsible Down Standard”, purchasing down products only from an RDS Certified supplier. That’s super important to me as a person and as a consumer, so I’m happy to support a company who has our environment and our fowl-friends at its heart as well. Plus Big Agnes is located in Colorado, where they know a thing or two about cold weather and living in the great outdoors.

Hood design

The hood design is pretty awesome. It’s contoured to the shape of your head and it has an internal anti-draft collar that keeps cold air out. A cord lock on the side of the hood can be cinched or un-cinched with one hand, so it’s not only cozy but also easy to use. I tuck my Sea to Summit pillow right into the hood, cinch it down and sleep like a log! The pale blue interior shows some dirt around the inside of the hood after only about a month of nightly use while thru-hiking. Did my bad breath cause that? Or my dirty, dirty hair? Geez Louise! The dirt wasn’t a big deal, but maybe a darker color for the bag’s liner makes a bit more sense to me.


This sleeping bag has a zipper garage that is backed by an anti-snag draft tube, but my zipper did snag more often than I would have liked. The draft tube portion did a good job of keeping wind from blowing in, keeping me extra warm! And the garage part means you can pull the zipper tie into your bag and tuck it in. That’s a nice feature, so the zipper pull doesn’t poke you, but I didn’t use it very often. I run hot then cold, so some nights I’m constantly zipping and unzipping. Plus, getting up to leave the tent for midnight urine runs…well, both of those, I guess it’s an age thing… 😉

Pad sleeve

The Sydney is designed to be used with the REM Pad Sleeve that lets you clip the storage sack to the back of the bag and then slide your pad in. It’s supposed to keep you from rolling off the pad during the night. I didn’t use that option, because I was cutting weight wherever possible. I use a Sea to Summit pad and don’t really have an issue with sliding off the pad except for the time or two we ended up on bad slopes. The sleeve does get excellent reviews by those who use the system and I’d probably be inclined to use it when car camping. I do use the sack for storage to give the sleeping bag room to spread out a bit.

Big Agnes Sidney Sleeping Bag
Big Agnes Sidney Sleeping bag

Inside pocket

There’s an inside zipper pocket which I thought was a good idea in theory, but I never actually use it much. I thought perhaps I’d tuck my phone into it, but don’t. I do sometimes keep a Chapstick in it and that’s nice to have so handy.

Inside liner loops

The Sydney has interior fabric loops to attach a sleeping bag liner (2 at the shoulder and 2 near the footbox) but I never use those either.  Seems to be a theme here. This bag is a Cadillac, but frankly I really use it as just a normal bag and don’t take advantage of all the extras.  I actually like having my liner loose so I can easily tuck it between sweaty legs if need be. The inside of the bag is made with nylon taffeta, that’s super soft and cozy.

Even though I don’t use all the functionality that the Sydney offers, I still love it!  I do not like to be cold, should I say that again?  I do not like to be cold and this bag keeps me warm.  It also did great in the desert, where I kept it unzipped and used it more like a quilt.  My last bag was a Marmot.  I bought it sometime in the 90s and it’s still in fantastic shape.  It’s just heavy.  I kept it for car camping, but by switching to the Sydney, I was able to shed almost 3 pounds, without sacrificing any comfort or warmth. 

This is a great bag for backpacking or car camping. It’s light, it’s warm and it packs down tightly in my backpack. I keep it in the stuff stack most of the time, but have also just stuffed it into the pack also. It’s a very comfortable sleeping bag. Just writing this review makes me want to sleep out under the stars tonight!

Would I buy it again?

Yes! The Big Agnes Sidney sleeping bag is light weight, but warm.  It also works well draped over me as a quilt in warmer weather, with my feet tucked in the vaulted footbox, since they always get cold.  It’s a versatile bag with a lot of great options for personalization.  It packs down fairly small.  So yes, I’d buy this sleeping bag again in a heartbeat!  Plus, I really, really love the name Big Agnes.  It makes me smile.


  1. Heidi Halverson

    Countdown? He’s got like 100 miles. Am I right? Go Steve, Go. I’m caught up on the blog. This is super exciting.
    10 days? Are we taking bets?

  2. Heidi Halverson

    You look so cute! I love the picture.


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