Mountain Hardwear Phantom 0F Sleeping Bag Review

We purchased the Mountain Hardwear Phantom 0F Sleeping Bag so our expert reviewer could thoroughly test and assess it. Keep reading for our full product review.

Mountain Hardwear is a large outdoor gear brand with a reputation for serious outerwear and mountaineering gear since 1993. Their distinctive nut logo conveys that their products are tools, often for extreme conditions. I recently tested the Mountain Hardwear Phantom 0F Sleeping Bag in Colorado’s Rocky Mountains and foothills to find out if the bag delivered warmth and held up in the wide-ranging springtime mountain conditions.

 Comfort and Fit: Snug, even for a mummy-style

The Phantom 0F is a lightweight down bag that is essentially a puffy down jacket in sleeping bag form. Mountain Hardwear employs its proprietary 10D recycled Ghost nylon material as the exterior lining. The material is comfortable for sleeping and the 850-fill goose-down insulation is light and lofty to create a thick layer of insulation around your body.

The Phantom 0F utilizes the typical backpacking “mummy” shape that tapers down along the legs and can feel restrictive for first-time users. The reasons for utilizing a mummy shape are to minimize the space inside the bag that your body has to heat. (Your bag doesn’t actually heat you up in the night, your body heat does and the bag helps retain that heat.) The taper also minimizes the volume and weight of the bag—it's about 2 pounds, 10.5 ounces. That's good for backpackers carrying lots of gear and looking for ways to shave pounds.

The drawbacks of the mummy design mostly affect comfort, sadly, and may matter more to certain types of campers. Side sleepers, in particular, may get frustrated inside a mummy bag since it’s nearly impossible to bend your knees inside the bag. The Phantom 0F seems particularly narrow, though I found I could bend my knees with the bag rather than inside the bag in order to get to my preferred sleeping position. 

As tailored as the fit is along the body, it wisely allows extra room in the feet, which keeps the bag from compressing in one of the areas most vulnerable to getting cold. It also allows for some freedom of movement around the feet. 

It’s worth noting that I tested the regular size option, which felt snug but fitting for my 6-foot, 200-pound frame. Mountain Hardwear also makes short and long versions of this bag and based on my experience, anyone over six feet should look at the long version. Be sure to check out the detailed dimensions on Mountain Hardwear's product listing page for your best fit.

The hood is another area where the Phantom stands out, with a solid draft collar to hold in warmth. There's also a cinch to seal the hood around your head for when temperatures are at the lower end of the bag’s capabilities. These features also make the bag more comfortable by creating a de facto built-in pillow around your head even if that’s not their main purpose.

 Warmth: “Zero-Degree” with a caveat

Not surprisingly, considering the name, the Phantom 0F is rated down to zero degrees F. And while that puts it in the “zero-degree bag” category, it’s worth looking at the details since these aren’t standardized ratings across the industry. Typical to most sleeping bags, the lowest rating is the furthest you can push the bag—not necessarily in a comfortable way. For example, a tag on the Phantom 0F indicates a “comfort rating” of 13 degrees and a lower limit of zero. 

The lowest nighttime temperatures I was able to test this bag were in the low 20s and I found it comfortable. But if you’re planning to camp in temps at or below zero, you may want to consider a beefier bag. Likewise, if you are looking for a bag that works at temps around or above freezing, consider a lighter weight bag to which you can add a liner for colder outings.

The hood has features mentioned above that maximize your body’s internally generated heat such as a cinch for a solid face seal and the draft collar. The draft collar is made up of additional tubes of insulation that lay around the chest and upper back to keep warm air from escaping. 

The insulation is 850-fill goose down, which is some of the highest-quality down available and is likely one of the reasons the bag costs as much as it does. This fill rating means the goose down used is the lighter and more efficient grades of down so you get a near-maximum warmth to weight ratio. If weight isn’t a top priority for you, this bag—and others like it—may not be worth the extra spend.

Waterproofing and Breathability: Water-repellent

Waterproofing isn’t as key a feature in sleeping bags as it is for, say, rain jackets. But considering that goose down becomes nearly useless when wet, it’s important to keep your bag dry. The only information provided about the waterproofing is that there is a durable water-repellent finish on the nylon exterior which should keep moisture at bay as long as the coating holds up.

Because of its high loft and thickness, the bag isn’t particularly breathable. But considering the conditions it was created for, sweating isn't likely if used at the correct times. For example, I hopped in the bag inside at room temperatures and, not surprisingly, began to sweat almost immediately. This isn’t a ding on the Phantom and should just serve as a reminder to only use cold-weather bags like this in truly cold weather. Steaming out your bag and your tent can compromise the effectiveness of the down.

The silky exterior nylon is Mountain Hardwear’s 10D Recycled Nylon Ghost Ripstop which is woven to be more durable but is visibly so sheer and thin that you can literally see through it to the down. It’s worth pointing out that this type of material requires some care in handling since punctures can let the down-fill loose or expose it to moisture and decrease its effectiveness. 

Price: Pricey performance

At $620 on the Mountain Hardwear website, this isn’t a throw-it-in-the-car sleeping bag. At the cost of about four of their warm-weather bags, this is a specialty item for serious mountaineers and backcountry adventurers that push camping into colder seasons. If that’s not your case, consider one of our other backpacking picks.