Mountain Hardwear Phantom 0 Evaluation

Bottom Line

The Mountain Hardwear Phantom 0 is a true powerhouse for frigid conditions and one of the warmest backpacking bags we’ve tested. With 850-fill-power down, a full-length draft tube to seal in heat, and a generous down collar to bolster the fluffy insulation, you’ll stay extra cozy in cold conditions. This is Gear Analyst Ian Krammer’s go-to bag for camping from November until April in the Utah desert and the Colorado high country, where he’s stayed comfortable from sunset til sunrise on the longest, coldest nights of the year. Despite being lighter and more affordably priced compared to many winter bags, it has an outstanding warmth-to-weight ratio, and features like the no-snag zipper, included compression sack, and ethically sourced down are just the cherry on top.

However, the Phantom 0’s fit is narrow, which is a bit restrictive if you like to spread out. The comfort rating of 13°F means it may not be warm enough if you’re camping in temperatures under 15-20°F. And, while the bag is well-priced for a 0°F bag, it’s still a major investment compared to other options.

Warmth

The Mountain Hardwear Phantom 0 is a no-brainer for all-season adventurers. It’s specifically made  for camping in frigid shoulder season weather and winter, or for cold sleepers who have a hard time staying warm at night.  Two important things to look at when deciding if a sleeping bag is going to be as warm as its temperature rating suggests are fill power and fill weight. The Phantom is stuffed with 30 ounces of 850-fp down – anything above 800-fp is generally considered very high-quality down, so this bag leads the pack for warmth.

The Phantom also has a full-length draft tube and a wraparound draft collar that really seal in the heat on chilly nights. This bag also uses Gore-Tex to shed water on trips when wet down simply isn’t an option. It’s important to keep in mind that the Phantom’s comfort rating is 13°F, so most people probably won’t stay comfortable all the way down to 0°F, but that’s not what most people need most of the time. Hikers heading into the backcountry in sub-freezing conditions, or those that aren’t staying warm with a higher temperature bag on a decently insulated sleeping pad, will love this exceptional winter sleeping bag.

The only downside of the incredible warmth, huge loft, and plush feel of this bag is it’s too warm for most summer adventures. If you’ll be camping regularly in temperatures at or above 40°F, we recommend a more breathable and lightweight bag with a higher temperature rating.

Comfort

Not only is this bag one of the warmest options for backcountry nights, it’s one of the most comfortable. The 20D nylon taffeta fabric is so smooth and gentle against the skin that we always look forward to slipping into the Phantom 0 after a long day of snowshoeing, skinning, and trudging through snow and ice. The generous down collar and draft tube lock in warmth, and the no-snag zipper and long zipper pulls make for easy, comfortable access from inside or outside the bag. We also like the easy-to-use cinch cords for the hood, and the compression sack is a bit stretchy for easy packing on cold mornings before hours of backcountry travel.

Our only complaints are that the bag’s fit is a little narrow, which feels restrictive for folks who sleep on their stomach or spread out like a starfish while sleeping. And, the overstuffed draft collar is awesome for locking in heat on very cold nights, but it’s a bit bulky and cumbersome on slightly warmer evenings when we prefer more ventilation.

Weight & Packability

Coming in at 2 pounds, 10.6 ounces, the Phantom 0 is one of the heavier sleeping bags on our backpacking guide – although compared to competitive winter sleeping bags, it’s definitely one of the lighter options we considered. Mountain Hardwear effectively keeps the weight down with tons of compressible and airy 850-fill down insulation and a lightweight 10D recycled shell, without skimping on features that are essential to keep you warm in the snow and ice, like a durable Gore-Tex shell, overstuffed draft tubes, and a large, heavily baffled hood. But, these are the same elements that make it one of the heavier bags.

But, this weight is certainly not a dealbreaker. The Phantom 0 comes in at a lower weight and price compared to most winter sleeping bags, so it’s our favorite recommendation for cold sleepers and year-round explorers.

Features

The Mountain Hardwear Phantom 0 Sleeping Bag is packed with features that make it perfect for cold nights in the backcountry. The durable, smooth 2-way zippers – including glow-in-the-dark zipper pulls – provide easy ventilation and hassle-free entry and exit. The mummy cut efficiently maximizes the warmth-to-weight ratio, and the large, four-chamber hood is big enough to accommodate a backpacking pillow and keeps the warmth wrapped around your head. The Gore-Tex exterior provides excellent weather resistance, and this model also comes with left-hand and right-hand zippers so you can zip two bags together, making it a versatile choice for couples and groups to share warmth while camping. Mountain Hardwear also includes a lightweight nylon compression sack and a mesh storage sack, so it’s easy to pack and store the bag at home and in your backpack. 

Despite its many features, the Phantom 0 has a few drawbacks. Occasionally, the zipper will slide down when moving around in the night, potentially letting in cold air. We love the contoured foot box for retaining warmth, but the bottom half of the bag is narrower than some might prefer, restricting foot movement, and wide sizes are not available. And the Gore-Tex exterior, while adding durability and weather resistance, can sound a bit noisy and make the bag stiff and less compressible compared to other materials. Still, these are minor issues. The Phantom 0 is the boss of cold-weather features and a leader when it comes to high-performance winter sleeping bags.

Should You Buy the Mountain Hardwear Phantom 0?

The Mountain Hardwear Phantom 0 is a dream for dedicated winter adventurers and those who frequently camp in cold conditions. With its impressive warmth-to-weight ratio and high-quality 850-fill-power down, this one is perfect for hikers and campers who need reliable insulation in temperatures well below freezing. The generous down collar and draft tube effectively block the coldest chills. You’ll be hard pressed to find a lighter, more durable, or effective down backpacking dag for camping in harsh, chilly environments. 

However, the narrow fit may not be as comfortable for nighttime tosser-turners, and its high price point – one of the most expensive bags we considered – may be a barrier for budget-conscious buyers. It’s also specifically designed for sub-zero temperatures, so the Phantom may be too heavy, warm, and bulky for most backpackers and most hiking climates. That said, the Phantom 0 is the golden egg for hikers who want the best of the best for warmth and comfort in sub-zero temperatures from the dry, open desert to the snowy alpine.

What Other Backpacking Sleeping Bags Should You Consider?

Sea to Summit Spark 15 Review: Similar to the Mountain Hardwear Phantom 0, the Sea to Summit Spark 15 offers excellent warmth-to-weight ratio in a smart, mummy-style design with high-quality down fill. However, the Spark 15 is a full pound lighter and much more compact, making it better suited for ultralight backpacking at colder temperatures.

Western Mountaineering UltraLite 20 Review: When it comes to top-of-the-line bags made by cottage companies with an eye towards quality, the Western Mountaineering UltraLite 20 is directly competitive by price, fill power, and warmth. The UltraLite 20, however, is lighter, has a higher temperature rating, and offers a wider cut, making it more comfortable and versatile for more users.

Feathered Friends Swallow YF 20 Review: Comparable to the Mountain Hardwear Phantom 0 in terms of high-quality down fill, best-of-the-best comfort, and excellent warmth. However, the Swallow YF 20 is less expensive, has a higher comfort rating, and weighs significantly less – and for a slightly higher fill power.