Western Mountaineering Kodiak MF Review

The Western Mountaineering Kodiak MF is impressive. From mountain guides to mountaineers, every one of our testers has lauded its remarkable warmth-to-weight ratio and spacious comfort. What sets this bag apart is the premium, ethically sourced 850-fill power goose down, and its continuous baffle design that lets you shift the insulation where you need it to stay cozy in harsh conditions.

Weighing just 2.80 lbs, this bag is incredibly lightweight and packable, perfect for long treks. Initially, its weather-resistant shell generated confidence when faced with wetter conditions. Unfortunately, however, we found the DWR coating diminished in effectiveness over a year of use, reducing the protection it can offer over time.

Though expensive, this bag is a worthy investment for adventurers who value top-notch performance and thoughtful design. Western Mountaineering is known for paying attention to what works, using time-tested common-sense designs and high-quality materials to provide the best product for serious adventurers.

Warmth

At the end of a long day in the cold, the Kodiak MK beckons with seven lofty inches of down created by 1.9 pounds of ethically sourced 850-fill goose down. This bag is warm and cozy even at temperatures slightly below its zero-degree rating. One tester, Jacob Holmes, found that it works well down to -10 F° by adding a down blanket. He found that the Kodiak doesn't just trap warmth, it seems to reflect it at him in a way that feels distinct from other bags in the test. A second tester described her experiences as the mirror to his, saying, “I find I don't even need to zip this bag up until temperatures drop well below freezing.” When one tester learned the Kodiak had the same rating as some other 0-degree bags, they couldn't help but laugh — it's so much warmer than the rest, there's limited direct competition.

Western Mountaineering doesn't use EN ratings or provide a range of comfortable temperatures. The website simply states that the Kodiak MF is a zero-degree bag. Based on extensive testing, the Gear Lab team feels Western Mountaineering tends to be conservative with its temperature ratings. Aside from testing this bag in the field, our test team also performed a controlled test back in the lab, laying still in each bag for 20 minutes in single-degree temps, carrying temperature and relative humidity sensors inside. This bag performed more in line with the -20°F bag in the test than most other 0°F bags.

Continuous baffles allow you to move the downy insulation where you need it and, since they have fewer stitches than other styles, they give the feathers enough room to maintain their incredible loft. The bag's spacious interior does an excellent job of retaining heat for medium to large people. It took smaller people (like our 5-foot-6-inch, 135-pound tester) longer to warm up in the bag. She says, “On nights that dip below zero, I like to fill the dead space with hot water bottles, puffy jackets, or a down blanket.”

The extra room in the bag makes it easy to find a comfortable position or change clothes for the day without getting tied up in knots. And, unlike what we see with some other bags in which tossing and turning can expose cold spots, the Kodiak MF seems to hold consistent warmth around larger bodies.

This bag's puffy, high-loft construction extends to its hood and collar. An interior drawstring around the collar and a separate cord around the hood allow you to fine-tune its fit for different conditions. On particularly frigid nights, you can cinch down the face hole to a mere 4-inch breathing hole. The adjustable collar stops cold drafts from creeping in, as does a down baffle that runs the length of the zipper.

A hook-and-loop closure strip connects the collar across the gap created by the zipper. It's effective, but awkward to use. A second latch holds the zipper in place, keeping it from slipping and opening the bag every time you shift positions. The high zipper reduces the hood opening from the start, effectively holding warmth around your face. '

Both drawstrings are thin but seem sturdy. The plastic cinches that hold them closed release with little pressure. This is a common feature among winter sleeping bags, and allows you to escape in the morning after you batten down the hatches at night.

Overall, the Kodiak MF sleeping bag's overstuffed feel, high-quality down, and smart features prioritize heat retention without sacrificing comfort, letting you dress for the day while still enveloped in warmth from the night before.

Moisture Management

Over the years, our testers have used the Kodiak MF in fog, mist, and light precipitation, and it's never soaked through in the field. Unfortunately, we found things a little different this year. While spills initially rolled off the fabric in testing, after a year of regular use, we saw a change. Our tester reports, “When a puddle of water was left on the fabric for 10 minutes in this year's test, I found it soaked through the fabric and into the down coating.”

The bag's goose-down insulation is also susceptible to moisture. When down gets wet, the feather structure collapses, eliminating the air pockets that trap warmth. So, while dry snow brushes off, and the weather-resistant MicroLite XP fabric is breathable and dries quickly in the sun, standing water or heavy wet precipitation is an issue. If you're looking for a more weather-protective option, Western Mountaineering does offer Gore Windstopper models, though they cost and weigh more.

Luckily, when it's cold enough to use this bag, liquid water is often in short supply. If you use warm water bottles at night to keep the bag toasty in lower temps, ensure the lids are secure. Other sources of moisture include sweat, damp clothing that you take in your bag to dry, and your own exhalations. The breathable fabric helps most of these potential sources of dampness escape on their own. A two-way zipper gives you venting options on warmer nights, and the adjustable collar blocks moisture from your breath, reducing condensation in the bulk of your bag to keep you drier and warmer overnight.

Comfort

This bag is ridiculously comfortable. The silky liner and ultra-puff of the mega-stuffed baffles make crawling into it delightfully luxurious. The draft tube at the collar perfectly adjusts for a snug fit, and the two drawstrings in the hood allow you to customize the fit easily. You can cinch it tightly on cold nights to hold warmth around your face; you can leave it open when it's warmer to let heat escape.

The size regular was large enough to accommodate our smaller tester (5 feet 6 inches and 135 pounds) and any gear she needed to keep warm for the night. It also fit another 6-foot-tall, 170-pound tester, who usually requires a long bag to stay warm and comfortable through the night. The bag was roomy enough for him to sleep on his stomach with his arms above his head and still allowed him to easily access his feet to change socks and dress comfortably on frigid alpine starts.

At 67 inches in the shoulder, it has the most generous cut in the review. Side, stomach, and starfish sleepers alike will all appreciate this roomy cut. That extra space eliminates the feeling of claustrophobia that a mummy bag can evoke. It also allows plenty of room to sleep with hot water bottles, your electronics, boot insoles, and tomorrow's clothes.

The zippers are easy to find and are lined by a stiff, snag-reducing ribbon of fabric. It helps, though you do need to move slowly when unzipping it from the inside to prevent snagging. The two-way zipper opens at both the top and bottom for efficient venting.

Tester Jacob Holmes rated the Kodiak MF sleeping bag's comfort “A big, fat excellent!” Our second tester, Clark Tate, agrees, “Between its spacious cut, overstuffed cloud feel, and silky fabric, this bag is a backcountry dream.”

Construction Quality

The time-tested design and no-nonsense construction of the Kodiak MF work well, and the high-quality, ethically sourced goose down incorporates a ridiculous amount of loft and warmth. The exterior shell is made of 20D MicroLite XP nylon with a ripstop weave. It's incredibly lightweight, allowing you to enjoy the bag's generous cut without paying a penalty in weight.

The fabric is thin, though, and easy to puncture with the tip of a paperclip. While the hole we punctured didn't run, it did warn us to keep this bag far away from our crampons and other sharp objects. We also discovered its fabric, which initially repelled water well, lost its effectiveness over the course of a year (although it still remained impressively wind-resistant over that time).

The classically styled metal zippers are sturdy in a way that would impress anyone's grandparents. Unlike modern options incorporating a plastic guide to prevent snags, this classic design is old-school. While durable, they are more prone to biting into the fabric and jamming than contemporary options with a zipper guard. A reinforced interior ribbon of stiffer fabric helps, but it's not as sturdy as other options we tried and we found it still gets sucked into the zipper on occasion. We saw the zipper grab the exterior shell about one out of ten times while quickly unzipping with a lot of force from the inside, although it never resulted in a jam or rip, and it was easily resolved.

The spaciousness of the bag and continuous baffles make it far more versatile than others in its class. However, the exterior stitching perforates the shell rather than hiding between the panels. If these seams get snagged, the material bunches and puckers. The 20D ripstop weave ensures toughness despite the fabric's flexibility and silky feel.

This bag's one truly disappointing element is the included “compression” sack. It's a basic drawstring sack without a roll-top closure or compression straps to cinch down. While that's fine for car camping, if you need to maximize space in your pack, you'll need to buy a better option separately.

Weight

The size regular Kodiak MF weighs 2.8 pounds or about 45 ounces. While this is not an ultralight bag when talking about summer bags (which usually come in between 1.5 and 2 pounds), it's incredibly lightweight for a winter bag. We don't know of a lighter bag that offers this kind of warmth, comfort, spaciousness, and durability. Heck, many far heavier bags can't compete with this bag's heat retention and spaciousness.

The 850-fill power down is light and lofty enough to hold more pockets of air per ounce, making it incredibly warm for its weight. The bag may be simple, but in the best way – 1.9 pounds of high-quality natural goose down with just 1 pound left for the lightweight, durable MicroLite XP shell, liner, zippers, and drawstrings.

Packed Size

Considering this bag's ample size and loft, its compressibility is like a magic trick. Seeing it come out of a stuff sack and loft up is like watching a memory foam mattress expand in an unboxing video.

Take note, though, you will need to procure your own compression sack. While the Kodiak MF comes with a basic stuff sack, sans compression straps, it's not waterproof, and doesn't compress the bag fully. This upgrade may cost a little more, but at the end of the day, extra space in your pack pays for itself.

Should You Buy the Western Mountaineering Kodiak MF?

This bag was tested in Maine, where our testers recommend choosing a -20 bag to stay safe in the Northern latitudes. That said, the Kodiak MF is the only 0-degree bag we consistently took into the backcountry since it proved it can easily handle temps to around -10°F. It's also the most comfortable bag in the test for broad-shouldered folks by far.

The Western Mountaineering Kodiak MF provides exceptional warmth with its 850-fill power natural goose down and continuous baffle design. It is lightweight at 2.8 lbs, making it ideal for backpackers and climbers who prioritize performance. It's astonishingly compressible for the amount of loft and interior space it provides. The Kodiak MF is the clear answer for larger people and active sleepers. Smaller people should probably sleep with a whistle just in case they get lost in there.

Despite its higher price point, it offers top-notch construction and durability, making it a worthy investment for serious adventurers. Our team of guides has a lot of experience in the backcountry caring for all sorts of people, and they have a critical eye for the details that matter most. This bag continues to impress everyone, earning it high scores and accolades from the team.

What Other Cold Weather Sleeping Bags Should You Consider?

If you are looking for a -20°F bag, the Nemo Sonic -20 is an excellent option. Exceptionally warm and lofty, it's also incredibly comfortable and well-priced. However, its narrow hood design is best suited to back or side sleepers. The Feathered Friends Snowbunting is another light and lofty stunner, with hardier fabric than the Kodiak MF to boot. It has a relatively narrow cut that isn't nearly as comfortable, though. If you'll be car camping and won't need to haul your bag around on your back, the Marmot Never Summer 0 is a less expensive option with a comfortable blanket-style cover, although it is drafty.