Zpacks 20F Classic Sleeping Bag Review

The Zpacks 20F Classic Sleeping Bag is an ultralight hoodless down sleeping bag that’s one of the lightest 20-degree bags available. It’s highly packable, surprisingly roomy, and inexpensive compared to many ultralight mummy-style sleeping bags. It’s a great option if you’re looking to lighten your sleep system without giving up the zipper of a sleeping bag.

Product Overview

Zpacks 20F Classic Sleeping Bag

Price: $399-$519

See on Zpacks

Pros

✅ Ultralight

✅ Very packable

✅ Roomy

✅ Less expensive than many UL sleeping bags

✅ Comes with DCF stuff sack

Cons

❌ Hoodless

❌ Small zipper

❌ Minimal extra features

KEY SPECS

• Weight: 1 pound 5 ounces (medium, standard-width); 1 pound 4.1 ounces (tested weight)
• Packed size: 10 inches x 5 inches diameter
• Temperature Rating: 20° Fahrenheit
• Fill: DownTek Water Repellent Goose DownDS
• Fill power: 900 fill power
• Fill weight: 13.7 ounces
• Length: 68 inches
• Shoulder Girth: 55 inches
• Hip Measurements: 22 inches wide (hips), 50 inches (girth)

The Zpacks 20F Classic Sleeping Bag is an ultra-minimal hoodless goose-down sleeping bag. It’s one of the lightest 20-degree sleeping bags on the market and is stuffed with ICEA “Responsible Down Standard” certified goose down.

This sleeping bag is unique among ultralight sleeping bags because it’s more similar to a backpacking quilt than other ultralight sleeping bags. The Zpacks 20F Classic Sleeping Bag is certainly a sleeping bag since it has a ¾ length zipper to wrap around you completely. But when you look at the design of the Zpacks Classic, you’ll see this is essentially a wide quilt with a zipper. The result is a sleeping bag with all the benefits of a quilt–lower price, weight, and reduced bulk–with the added versatility of zipping the bag closed when the temperatures drop. Also similar to a backpacking quilt, its semi-rectangular shape allows lots of room to move. Compared to many mummy-cut sleeping bags of similar warmth and weight, the Zpacks Classic is roomy.

The Zpacks 20F Classic is ideal for backpackers looking to cut weight from their sleep system who aren’t sold on the idea of a zipperless backpacking quilt. It’s less expensive than many ultralight sleeping bags and is warm enough for shoulder season and mild winter conditions. But, it’s more expensive than some backpacking quilts out there since it has a sewn-in zipper. If you’re looking for a sleeping bag with a hood, this isn’t the bag for you. The hoodless design saves weight, but you’ll have to carry a beanie, a puffy jacket with a hood, or both to keep your head warm at night with this sleeping bag.

Performance Test Results

How We Tested:

I have thru-hiked the Pacific Crest Trail, Continental Divide Trail, Grand Enchantment Trail, and Colorado Trail three times, along with countless shorter backpacking trips. I tested the Zpacks 20F Classic Sleeping Bag in winter on a series of backpacking trips in southern Arizona. The weather was cold overnight, with temperatures dropping into the 20s.

WEIGHT: 9/10

The Zpacks 20F Classic Sleeping Bag is as light as you’ll find in a bag rated to 20 degrees. On my home scale, the medium-length, standard-width bag I tested weighs 20.1 ounces. This is as light as some of the most lightweight sleeping bags out there. It’s almost as light as a down sleeping quilt, but this bag has a ¾ length zipper to close it entirely.

This bag didn’t score even higher in this category because it doesn’t have a hood. It is designed to only go up to your neck. It features a stretch cinch cord with a toggle to tighten under your chin to keep heat in. Since it doesn’t have a hood, you’ll also have to have a puffy jacket with a hood or a beanie, which will add some weight. However, most hikers carry a beanie already, so this is almost a non-issue.

This sleeping bag is designed to be as ultralight as possible. It is filled with DownTek 900-fill power water repellent goose down. The inner and outer shells are made with ultralight 7-denier Ventum Ripstop Nylon, which weighs only .51 ounces per square yard.

A medium-sized standard-width 20F Classic Sleeping Bag weighs 1 pound 5 ounces according to Zpacks but it only weighs 20.1 ounces (1 pound 4.1 ounces) on my home scale.

It has nothing extra that adds weight. It uses the smallest zipper possible, and the zipper stops just past your knees to save weight. It has the thinnest shock cord for the neck cinch and nothing else in terms of features.

This sleeping bag comes with an ultralight rolltop DCF stuff sack, which weighs 0.7 ounces and is waterproof. It also comes with a small roll of ripstop repair tape, but this doesn’t even register on my scale. The total trail weight of this bag is 21.1 ounces, according to my scale.

Compared to competing sleeping bags, this bag is about as light as you’ll find. Some bags are slightly lighter and have a hood, but those bags are cut narrower than the Zpacks Classic. In most regards, it makes more sense to compare this sleeping bag to down backpacking quilts, since this is essentially a wider quilt with a zipper. Compared to down sleeping quilts, this is still one of the lightest you’ll find.

Since this bag is rated to 20 degrees Fahrenheit and weighs 20 ounces, the warmth-to-weight ratio is 1:1. This is incredibly light. Many 20-degree sleeping bags weigh close to 2 pounds (32 ounces), or a 1.6 to 1 ratio. There are even sleeping bags that have a 2:1 warmth-to-weight ratio, or higher.

PRICE: 9/10

The Zpacks 20F Classic Sleeping Bag is very competitively priced. This is one of the least expensive bags available compared to other ultralight sleeping bags with a similar warmth-to-weight ratio.

This bag is so inexpensive because it uses a simpler design than most ultralight sleeping bags. As I said above, this sleeping bag is basically a quilt with a zipper, since it’s hoodless and doesn’t have many extra features. I prefer simpler bags that aren’t shaped to conform tightly around your body, with a tight-fitting hood and other weight-saving features. A simpler design also happens to mean a less expensive sleeping bag, like the Zpacks Classic.

There are less expensive sleeping bags available, but they aren’t as light as this bag. There are, however, less expensive quilts than this sleeping bag. A backpacking sleeping quilt doesn’t have a zipper, though. If you want a sleeping bag that zips shut and is lightweight, the Zpacks Classic is one of the least expensive you’ll find.

For $449, you can buy a medium-sized and standard-width Zpacks 20F Classic Sleeping Bag.

COMPRESSIBILITY: 10/10

This sleeping bag packs down into a small DCF roll-top stuff sack. This sleeping bag is a nine-by-five-inch cylinder when packed into the stuff sack. I’m very impressed with the small size of this bag when packed down. When packed away, this sleeping bag is smaller than many tents, which says a lot. If it packed any smaller, I wouldn’t expect this sleeping bag would be warm enough for anything but warm weather backpacking.

Other than the stuff sack, the other factor affecting the packability is the 900-fill down used to insulate the sleeping bag and its overall minimalist design. This goose down is extremely packable but regains its loft quickly when unpacked.

You could pack this sleeping bag down even smaller than the 9x5 inch cylinder I referenced above, but then you’d struggle to pack it down with your fingers while rolling the stuff sack closure. I don’t recommend this mainly because it isn’t necessary. But, you also shouldn’t overcompress down for extended periods, and this stuff sack allows the bag to be compressed to a very small size as it is.

I find it’s very easy to back this bag into the stuff sack, and the roll-top closure makes compressing the bag after you’ve packed it more straightforward than some compression stuff sacks. I’ve packed a lot of sleeping bags away, and this stuff sack is just the right size to allow for maximum compression without hurting your fingers while you pack it away.

Compared with other ultralight sleeping bags, this bag is about as packable as it gets. As I said above, if this bag is packed down any smaller it would mean there is less down inside, which would mean it isn’t as warm.

This sleeping bag is very compressible. I rate its compressibility a perfect 10 out of 10.

WARMTH: 8/10

The Zpacks 20F Classic sleeping bag is rated to 20 degrees Fahrenheit. Twenty degrees is an adequate temperature for most three-season backpacking. From testing this bag, I feel like I wouldn’t want to rely on this bag below 25 degrees Fahrenheit, but I’m not a particularly warm sleeper. Either way, 20-25 degrees is about as cold as you should expect in most backpacking conditions during summer and shoulder seasons.

This sleeping bag does not have a hood, however. You'll need something to keep your head warm to push this bag to the limits of its temperature range. My strategy for hoodless sleeping bags and quilts is to use an ultralight fleece beanie and the hood of my puffy jacket. You should definitely bring a beanie and hooded insulated jacket when using this sleeping bag.

This sleeping bag also has a neck cinch cord made with an ultralight shock cord, so you can tighten it around your neck to trap the heat inside. It does not have a draft collar, but the vertical baffles bunch up around your neck when you tighten the neck cinch. It also has a ¾ length zipper and a closed foot box to keep heat in the bag.

It has vertical baffles down to the foot box, and then the baffles become horizontal in the foot box area. This allows you to push more down towards your core if you wear a jacket with this sleeping bag. It also lets you move the down around to the tops and sides of your foot box while preventing all the down from migrating out of the foot box portion of the bag.

This sleeping bag has not been tested for its International Standard Organization (ISO) rating. The ISO rating system is a way to standardize sleeping bag temperature ratings. Zpacks says their ratings are based on customer feedback and their own testing. But, they estimate that this bag is rated to 20 degrees “transition range.”

“Transition Range,” according to the ISO, means a standard man “in a situation of fighting against cold (posture is curled up inside the sleeping bag), but in thermal equilibrium” will not be too cold at 20 degrees. In other words, if you’re a man, you should expect this bag to be just warm enough down to 20 degrees, but you’ll be more comfortable when temperatures are closer to 30 degrees.

If you’re still trying to wrap your head around sleeping bag temperature ratings, check out this video on how to understand the rating system.

I’m a man, and I find this bag comfortable at 30 degrees. Since women tend to sleep colder than men, this bag should be warm enough for women down to about 35-40 degrees. Also, everyone is different, and comfort levels vary from person to person, regardless of gender. I would confidently say that this bag is about as warm as most bags with a similar temperature rating and fill weight.

As a general rule, I’ve found that if you look at the fill weight and dimensions of the bag, you’ll be able to get a pretty good idea of how warm it will be. From these numbers, you can know the total amount of down and how far it is spread throughout the bag.

SPACIOUSNESS: 9/10

The Zpacks 20F Classic sleeping bag is quite spacious for an ultralight sleeping bag. Some ultralight bags don’t allow you to move around in the bag, but I don’t find that to be the case with this bag at all. I tend to toss and turn while I sleep, moving from my side to my stomach and onto the other side throughout the night.

This bag is shaped with a gentle taper. It is widest at the shoulders and narrowest at the foot box. It starts out wider than many ultralight sleeping bags and does not taper very small near the foot box either.

I tested the standard width and medium height of this sleeping bag. This size bag is 68 inches long and has a shoulder circumference of 55 inches. It is 22 inches wide at the hips, with approximately a 50-inch girth. The foot box is also big enough so I can cross my ankles, which I sometimes do while I sleep or lounge in a sleeping bag.

At 5’9” and 165 pounds, I’m not particularly big. With this sized bag, I can sleep in any position, including curled up in the fetal position. I never feel cramped in this bag. If you’re shorter than me, or taller, you should order a “short” or “long” sized bag. If you’re more slender than me or only sleep on your back, you should probably order a “slim” width (up to 50-inch shoulder girth) of this bag. If you have broad shoulders or are otherwise larger than me, I’d recommend ordering the “wide” (up to 60-inch shoulder girth) version of this bag.

DURABILITY & OUTER SHELL MATERIALS: 8/10

The Zpacks 20F Classic sleeping bag is about as durable as any other ultralight sleeping bag. The 7-denier Ventum ripstop nylon material is not the most durable, but it’s durable enough if you take care of this bag.

I wouldn’t recommend sleeping directly on the ground with this bag. You’d be cold and uncomfortable if you did that, anyways. But, the thin ripstop material will rip if you lay on rocks or other sharp objects. Since it’s ripstop, any tears on the bag won’t grow if they do happen. This bag also comes with a roll of ripstop repair tape. If you get a rip, simply patch it with this tape, and the bag will continue to be usable.

Compared with similar warmth-to-weight sleeping bags, this bag is about as durable as the most durable. I’ve used a quilt with a similar outer shell material for multiple thru-hikes, and it’s still in great shape. I would expect the Zpacks Classic to last for 1000s of miles if you take care of it, too.

The Zpacks 20F Classic Sleeping Bag's outer shell material is Ventum Ripstop Nylon.

COMFORT: 8/10

The Zpacks Classic is quite comfortable for an ultralight sleeping bag. It is spacious enough for you to find the most comfortable position for you. It is also warm enough to be very comfortable in typical backpacking conditions, where it can get as cold as the low 30s or high 20s (Fahrenheit).

The inner shell material is a typical ultralight fabric, so it’s not the most comfortable. The inner material is pretty slippery, but this is common with ultralight gear. If you’re used to sleeping in ultralight sleeping bags, you’re probably already used to the feel of this material. If you aren’t used to the feeling of this lining and shell material, you should know that it is prone to sliding off an inflatable sleeping pad if you aren’t on a flat surface. But again, this isn’t unique to the Zpacks Classic Sleeping Bag. This is the case with every ultralight sleeping bag I’ve ever used.

There are certainly more comfortable sleeping bags out there. But those bags are significantly heavier. In the realm of ultralight sleeping bags of a similar warmth-to-weight ratio, the Zpacks Classic is comfortable for sleeping in any position and about as comfortable as it gets. A lot of ultralight bags don’t have enough space to let you move around inside, but this one does. This makes the bag one of the most comfortable ultralight bags available.

VERSATILITY: 9/10

The Zpacks 20F Classic Sleeping Bag is relatively versatile. It is warm enough for shoulder season hikes but probably only warm enough for winter camping if you sleep warm. If you unzip this bag, you can use it like a quilt during warmer conditions.

I would confidently use this sleeping bag for a thru-hike on the PCT or CDT, where overnight temperatures range from 20 degrees to 50 or more. This sleeping bag would likely be overkill on the Appalachian Trail during peak summer, but it would work since you can unzip it and use it as a quilt.

Compared to competing sleeping bags, this bag is one of the most versatile. The only thing that would make it more versatile is a longer zipper to unzip it fully. Then, you could use this sleeping bag like a fully opened quilt instead of a quilt with a sewn foot box. However, this would make the bag heavier and not quite as warm.

ZIPPERS: 7/10

This sleeping bag has a very small ¾ length zipper. I honestly expected the zipper to snag more often when using it, but it doesn’t catch the lining material very easily. There isn’t a stiff material next to the zipper, and if you do snag the ultralight material, it could rip. So, you should be careful when zipping this bag, even though it doesn’t snag easily.

The zipper is a YKK brand and features a small cord for a zipper pull. The cord makes finding the zipper while you’re zipped inside possible. If it weren’t for this zipper pull, I don’t think this zipper would be useable, especially while wearing gloves. The zipper does not have a zipper plow, as is found on many sleeping bags to prevent the zipper from snagging. I think this bag would be improved with a zipper designed to avoid snagging. But again, this zipper somehow doesn’t seem to snag as much as I’d expect. Maybe it’s too small to even snag.

It is difficult to operate the zipper with the bag underneath you, though. And, the bag doesn’t have an extra flap of material to prevent heat loss through the zipper. So, it should be underneath you while you sleep for maximum thermal efficiency. The solution I’ve found for this is to rotate the zipper to the side of the bag while I’m sitting inside, zip it closed, then rotate the zipper underneath me. This solution works, and this design is best for saving weight, but it isn’t the most convenient.

 3/4-length zipper

DESIGN & FEATURES: 6/10

The Zpacks Classic is a minimalist sleeping bag. It does not have many features, but the ones it does have are listed below.

Draft Collar: 6/10

This sleeping bag does not have a draft collar. It has vertical baffles that bunch up around your neck when you tighten the neck cinch cord. This essentially operates as a draft collar but isn’t quite the same. Since there isn't a draft collar, you need to be sure there is plenty of down at the top of every baffle.

Foot Box: 10/10

This foot box is just spacious enough to let you move your feet into any position. I wear size 9.5 men’s shoes and can cross my ankles while lying on my back. I find any foot box that allows me to do this is big enough. It’s also not too big, so the bag isn’t unnecessarily heavy.

Stuff Sack: 10/10

This sleeping bag comes with a DCF roll-top stuff sack. The stuff sack weighs 0.7 ounces and is waterproof. The roll-top closure makes it easy to securely close the stuff sack to create a watertight seal while compressing the sleeping bag within.

Ripstop Repair Tape: 10/10

This bag comes with a 15 x 1-inch strip of repair tape for the ripstop shell and lining material. This strip of tape doesn’t even register on my home scale. Most sleeping bags don’t come with repair tape at all, either.

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