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20F Zpacks Classic Sleeping Bag Review | Ultralight Warmth

So, you want the lightest of the light but still need to stay warm in the backcountry? You may want to take a look at this Zpacks Classic Sleeping review. The Zpacks Classic Sleeping Bag is one of the the lightest sleeping bags you’ll find on the market. Then again, that’s not surprising coming from Zpacks. They consistently produce some of the lightest weight backpacking gear you can find. The real question, though, is how does it perform when it counts?

I tested the 20 degree model for this Zpacks Classic Sleeping Bag review, and one of the first things I noticed when I got the Classic Sleeping Bag is that it compresses down so small it’s ridiculous! Pair this classic sleeping bag with one of the Zpacks’ tents like the Zpacks Duplex (see our review of the Zpacks Duplex here), the Zpacks Plexamid, or the Zpacks Altaplex (see our review of the Altaplex here) and you could easily find yourself under 4 pounds for your entire camp setup. I don’t know about you, but that’s pretty dang appealing to me!

Zpacks Classic Sleeping Bag Specs

Zpacks Classic Sleeping Bag Review

The Zpacks Classic Sleeping Bag boasts some of the most impressive specs you are going to find on the market. Coming in at a scant 18.8 ounces for the 20 degree regular length (6 foot model) and standard width is pretty impressive. Here are some of the other specs for the Zpacks Classic Sleeping Bag:

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Zpacks Classic Bag Specs (Reg Length & Width)
Weight 18.8oz
Packed Size 12in x 6in
Down Fill 13.7oz
Shell Weight 5.1oz
Fits Shoulder Width 50in
Shell Material .51oz 7D Ventum Ripstop Nylon
Down Insulation 900fp Goose Downtek Water Repellent
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The Sizing: Zpacks Classic Sleeping Bag Review

Zpacks Classic Sleeping Bag Review

The Zpacks Classic Sleeping Bag comes is three different temperature ratings, a 10 Degree, 20 degree, and 30 degree. The Classic Sleeping Bag also comes in three different widths (slim, reg, and wide), along with three different lengths (short, reg, and long). I found the Zpacks Classic Sleeping Bag to run pretty true to size, as a regular size fit me just right. 

Now, I typically lean to getting a wide model, but the regular was just about right, so if anything, the Classic Sleeping Bag runs a touch on the wide side. The reg width was perfect and gave me plenty of room to move freely, but not so much that I had a lot of dead air space to heat and lose thermal efficiency.

The Weight: Zpacks Classic Sleeping Bag Review

Zpacks Classic Sleeping Bag Review

You’d be hard pressed to find a more ultralight sleeping bag than the Zpacks Classic Sleeping Bag.  Other than a quilt, I haven’t been able to yet. You’d expect to give up a lot to get something so insanely lightweight, but that simply isn’t the case. We’ll talk more below about what you DO give up to achieve this weight, but the Zpacks Classic Sleeping Bag lineup ranges from 12.2 oz for their slim/short 30 degree model, up to 25.9 oz for their 10 degree long/broad model. As you can see, even at 25.9 oz, that’s an incredible weight savings that can keep your legs and back fresh in the backwoods.

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From the 10 degree up to the 30 degree Zpacks Classic Sleeping Bag, check out how each model is sized and how much each of the variations weigh here.

Warmth: Zpacks Classic Sleeping Bag Review

Zpacks Classic Sleeping Bag Review

In all honesty, this is the area I was expecting the Zpacks Classic Sleeping Bag to suffer given its ultra light weight. And while that was the case to some degree, it didn’t give up as much as I expected. While the Classic Sleeping Bag didn’t quite hold to its 20 degree rating for me in my testing, it did come reasonably close. I found the 20 degree model that I tested kept me toasty warm down to the mid 20s. 

Of course, as with any sleep system, you’ll need to make sure you use a good, high R-Value pad appropriate for the temps you will be in. Your pad’s R-Value can be a determining factor in whether or not you stay warm.

Versatility: Zpacks Classic Sleeping Bag Review

Zpacks Classic Sleeping Bag Review

One of the super cool things about the design of the Zpacks Classic Sleeping Bag, is its ¾ length zipper that goes underneath you, while not having a hood like a typical sleeping bag.  At first glance you may think that’s odd and not a good idea.  Admittedly, that’s kinda what I thought.  I’ve tested a lot of sleeping bags and quilts, and this was a little different design no doubt.

Zpacks Classic Sleeping Bag Review

The idea of no hood goes with Zpacks’ philosophy of shaving every ounce possible.  Like the Zpacks Quilts (and pretty much every quilt out there), no hood is nothing new.  How do you keep your head warm without a hood?  The Zpacks Goose Hood is FLAT OUT AWESOME for this.  It weighs in at a minuscule 1.3 oz and can be used not only for sleeping, but for any time your head gets cold. 

When you really think about it, it’s a great way to shave weight and have a multi-use piece of equipment.  Using your favorite beanie also works fine, but I’ve found that using a hooded base layer also works awesome because a hooded base layer protects you neck and shoulders from cold drafts.  Many ways to skin that cat rather than a hood.

Zpacks Classic Sleeping Bag Review

Another very useful design feature of the zipper being located on the bottom of the sleeping bag is the ability to use the Classic Sleeping Bag as a quilt when you don’t need the warmth of it being zipped all the way up.  While you don’t have the pad attachment system of the Solo Quilt, it’s easy enough you drape it over you on the warmer nights.  When the temps drop, simply zip it up and you have a regular sleeping bag that you can seal up for those cold temps.

Zpacks Classic Sleeping Bag Review

In addition to the 3/4 length zipper, you get a nice ultralight buckle with the Classic Sleeping Bag. This may seem duplicative, but it’s really not. Having this clip allows for a fast and easy transition from sleeping bag mode to quilt mode. In quilt mode, simply unzip the zipper, but leave the buckle secured and you can allow more ventilation if the temperatures are warmer. In sleeping bag mode, you simply zip up the zipper to seal out any unwanted drafts.

Drawstring: Zpacks Classic Sleeping Bag Review

Zpacks Classic Sleeping Bag Review

The draw strings used by Zpacks around the neck of the Classic Sleeping Bag is another area weight is saved. The draw cord is elastic and extremely thin. I was a little concerned that I’d break the drawstring when cinching it down around my neck, but over the last 2 years of testing between the Zpacks Solo Quilt and this Zpacks Classic Sleeping Bag, I have yet to have any issue whatsoever.  I’ve also found the thin draw cord to be very comfortable. I couldn’t feel the cord around my neck like some others I’ve tried, but was able to seal out the drafts perfectly.

Zpacks Classic Sleeping Bag Review

Down/Materials: Zpacks Classic Sleeping Bag Review

Zpacks Classic Sleeping Bag Review

Like the Solo Quilt, the Zpacks Classic Sleeping Bag uses a super plush, responsibly sourced DownTech water resistant 950 fill goose down. If you’ve ever had the pleasure of trying out a 950 fill down sleeping bag or quilt, you know how awesome it is!  It feels so lightweight that you begin to question how on earth it can keep you warm, but it will.

Also like the Solo Quilt, the Classic Sleeping Bag does not have any sewn through areas, and uses vertical baffles on the upper portion of the quilt and horizontal baffles for the footbox. The vertical baffles located on the upper portion of the quilt help keep the down in place when tossing and turning.

Zpacks Classic Sleeping Bag Review

Zpacks uses a proprietary material called Ventum Ripstop nylon that is DWR treated to be water resistant, cuts wind while allowing for excellent vapor transfer and breathability, and weighs in at just .59 oz per square yard. To top it all off, it’s super soft to the touch and extremely comfortable!

Footbox: Zpacks Classic Sleeping Bag Review

Zpacks Classic Sleeping Bag Review

The Zpacks Classic Sleeping Bag features an oversized footbox designed to give your feet the space needed so your feet don’t push against the down, causing a cold spot.  I found the footbox to be extremely comfortable, a good surprise for such an ultralight quilt.  The footbox features horizontal baffles rather than vertical baffles which transitions about mid shin.  The footbox appears to have some added down as my feet never even hinted at getting cold even when temps dropped to the lower limit of the sleeping bag.

Zpacks Goose Hood

When using the Zpacks Classic Sleeping Bag, and any quilt for that matter, you’ll need to have a way to keep your head warm.  I’ve used a hooded base layer for those times when the temps aren’t too terribly cold, and that worked really well. However, if you want something a little warmer, the Zpacks Goose Hood is flat out AWESOME!  Made of the same 950 fill goose down and weighing less than an ounce, it’s more than worth its weight and keeps your head toasty warm.  In fact, it can also be used to keep your head and neck warm while glassing, etc. Once you wear one, you’ll likely not go back.

I tested the Zpacks Goose Down Hood down to the low 20s and I’ll absolutely be taking this thing with me every single time.  The small draw cord (similar to the one around the neck of the Solo quilt) can be drawn around your face to seal out the cold.  This is a must if you tend to get a cold head or maybe don’t have a full head of hair.  Best yet, when the temps really drop, it gives you more coverage for your face than a typical hood on a sleeping bag at a fraction of the weight.

What I Liked: Zpacks 20F Classic Sleeping Bag Review

Zpacks Classic Sleeping Bag Review

As you can image, one of the primary benefits of the Zpacks Classic Sleeping Bag is the weight savings.  It is so incredibly light weight and is sufficiently warm in comparison to its temperature rating that it’s hard not to take this bag on the trail.  Coming in at a mere 18.8 oz for the standard length and width in the 20-degree model it really does keep the weight to an absolute minimum.  I really like the footbox and the pad attachment strap system.  The Ventum material is silky soft and the 950-fill goose down is amazing! 

The Classic Sleeping Bag is so light and compact that it’s hard to believe it actually keeps you warm into the mid to low 20s, but it did for me.

  • Weight
  • Compact Size
  • Footbox
  • Ventum material
  • Quality
  • Roll top compression bag included

What I Didn’t Like: Zpacks 20F Classic Sleeping Bag Review

No Draft Collar

Zpacks Classic Sleeping Bag Review

While there was so much to love about the Classic Sleeping Bag, there were a few things that could have made it better.  One of which would be to have a draft collar.  I understand this is a minimalist style sleeping bag, but in a 20 degree (and especially in the 10 degree) sleeping bag, a draft collar around the neck would sure be nice.  The Classic Sleeping Bag did keep draft out pretty well, but a draft collar, even a small one, would be something I’d gladly carry an extra ounce to have.


Zpacks Classic Sleeping Bag Review

A little more of that 950 fill goose down wouldn’t add any substantial weight but would give you an extra warmth boost to get you down to the temperature rating.  Between the extra down and a draft collar, you might add a couple ounces max, but you’d have a super warm quilt that is still minimalist in design.  But, at the end of the day, that’s what a minimalist sleeping bag is… shaving every possible ounce, so I understand.  I’d also like to see Zpacks include a large long-term storage bag for the off season to protect your investment during storage.

  • No draft collar
  • Little more down
  • No large storage bag included

How to Store a Down Sleeping Bag

Zpacks Classic Sleeping Bag

Zpacks doesn’t give you a mesh storage bag with the Classic Sleeping Bag, but gives you an awesome dyneema compression dry bag to make sure your Zpacks sleeping bag stays dry and compact for the trail.

It’s easy to get home from your final adventure of the season, unload your gear, and throw it all in a storage bin for the winter, but make sure you properly store your down sleeping bag as well as your insulated sleeping pad. Don’t leave that high quality sleeping bag in its stuff sack long term as it could reduce the effectiveness of the down. Down needs to be lofted, not compressed when stored, and should be stored indoors if at all possible.

Here are a couple of storage options to keep your down sleeping bag at its peak performance.

  • Hang in a closet
  • Lay under your bed
  • Store in the storage sack provided (shown above)

Hanging a down bag is my first choice, but not everyone has the space for that. Most bags come with sewn in loops to stick on a hanger. Second to that, I prefer to store the bag lying flat under my bed. This allows the down to be fully lofted. Finally, storing in the provided storage sack is perfectly acceptable as well. The down is slightly compressed in those storage sacks, but nothing that will cause any damage to the down in your bag.

Picking the Right Sleeping Pad

Zpacks Classic Sleeping Bag

Selecting the right sleeping pad is even more critical when using a quilt, so make sure you get one that’s warm enough. Generally I like to add around 1 point in R-Value when using a quilt vs a sleeping bag to make sure the cold air from the ground isn’t the cause of a cold night’s sleep. A good high R-Value pad like this Sea to Summit Ether Lite XT Extreme, with a 6.9 R-Value will add a few degrees to most sleeping bags. For me in my testing, it added about 5-7 degrees to the same sleeping bag/quilt vs when using one with a 3 R-Value.

Using a higher R-Value pad will ensure that you are getting everything possible out of your sleeping bag or quilt. often times, it’s worth the few extra ounces if temperatures may be pushing towards the lower limit of your sleeping bag or quilt.

Check out our sleeping pad reviews for some great options with a quilt! Not digging a quilt? We’ve tested a ton of sleeping bags as well. Check out our sleeping bag reviews!

My ratings for the Zpacks Classic Sleeping Bag

Overall Ranking

Conclusion: Zpacks 20F Classic Sleeping Bag Review

So, after doing this Zpacks Classic Sleeping Bag review would I recommend Classic Sleeping Bag?  If you are looking for the lightest weight, minimalist style sleeping bag, while being okay with giving up a few small comfort features like the draft collar and hood, then absolutely!  If you are someone looking for a sleeping bag with all the bells, whistles and comfort features, then I’d recommend taking a look at a Feathered Friends Sleeping Bag or Sea to Summit Alpine.  Ultimately though, it’s tough not to love what this Zpacks Classic Sleeping Bag offers, especially if you are an ounce counter!

Buy a Zpacks Classic Sleeping Bag

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2 thoughts on “20F Zpacks Classic Sleeping Bag Review | Ultralight Warmth”

  1. Thanks. Great review.

    I got confused when you said they don’t provide a storage sack, but they do provide a stuff sack. Then you say keeping it in the stuff sack will reduce the effectiveness of the down, but then you say we should keep the bag in the provided storage sack.

    • Hey there! Thanks for the comment. Maybe I didn’t state it clearly….sorry for that. I meant that if you store the sleeping bag long term in the stuff sack (which is meant to be used when backpacking and compresses the down significantly), it will cause the down to lose loft over time more quickly. It’s a better idea to leave the bag lofted in a long term storage bag, but Zpacks does not provide one of them with the bag (they do provide a stuff/compression sack though). Thanks for reading!


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