Rab Mythic Alpine Down Jacket Review

Over the years, I’ve tested a number of premium down jackets, with standouts like the Mountain Hardwear Ghost Whisperer and Arc’teryx Cerium consistently topping my list. But after a season of use, Rab’s Mythic Alpine Down Jacket has earned its place among the best. Blending ultralight materials, lofty hydrophobic goose down, and a trim, mountain-ready fit, the Mythic Alpine hits a sweet spot for active pursuits in the cold. From skintrack transitions in the backcountry to chilly evenings above treeline, it’s proven to be a remarkably warm and packable layer that I now reach for on just about every alpine adventure. Below, I break down my experiences with the Mythic Alpine, including warmth, weight, weather protection, durability, and more. To see how it stacks up to the competition, see our articles on the best down jackets and the best men's down jackets.
 

Table of Contents

• Warmth
• Weight and Packability
• Weather Resistance
• Construction and Durability
• Key Features
• Fit and Sizing
• Sustainability
• What We Like/What We Don't
• Comparison Table
• The Competition

Performance

Warmth

Rab’s Mythic line is built around the concept of maximum insulation with minimal weight, and the Mythic Alpine strikes an impressive balance between the two. Stuffed with 4.9 ounces of high-loft 900-fill-power European goose down, it delivers serious warmth that’s immediately noticeable the moment you put it on—far more than competitors like the Mountain Hardwear Ghost Whisperer. It’s become my go-to insulator for everything from cold-weather ski touring and snowshoeing to crisp vanlife mornings and après-ski hangs. For context, the lighter Mythic Alpine Light version features 2.8 ounces of the same down, while the beefier Mythic Ultra clocks in with 8.5 ounces for colder conditions. All told, the Alpine hits a sweet spot for most high-output winter pursuits and cold-weather backcountry travel.
 

Despite the lofty insulation, breathability is surprisingly good with the Mythic Alpine. I’ve worn this jacket under a hardshell while backcountry skiing in temps around -10°C (14°F) with steady snowfall, and not only did I stay warm, but my base layers stayed dry—impressive considering how warm I typically run. The down-filled hood and tall collar provide fantastic coverage (even without a cinch), and thoughtful details like extended cuffs and dual cinch cords at the hem do a great job sealing out drafts. During a snow pit dig in bitter winds in Strathcona Park, the jacket kept me comfortable and focused—a strong testament to its performance in harsh, real-world conditions.
 

Weight and Packability

At just 11.5 ounces for a men’s size large (11.0 ounces for men's medium), the Rab Mythic Alpine Down is impressively light given its warmth. It packs down to the size of a large grapefruit, edging out the Arc’teryx Cerium (11.9 oz., medium) while offering more insulation than other lightweight puffies like the Ghost Whisperer (10.7 oz., medium). It’s a near-perfect companion on weight-conscious missions where warmth is still a top priority, and has become my default layer for multi-day ski tours and winter overnights.
 

That said, the packability system isn’t perfect. The jacket comes with a separate, unanchored stuff sack that I’ve dropped more than once while digging around in the hand pockets. I’ve often opted to roll the jacket into its own hood or stuff it into a pocket, though neither option secures it fully. Still, the Mythic Alpine takes up minimal space in a pack, and part of its low weight is thanks to its pared-down design—there are no chest or interior pockets, and no cinch cord on the hood. If you can live without those extras, the warmth-to-weight ratio is hard to beat.
 

Weather Resistance

The Rab Mythic Alpine uses a 10-denier recycled Pertex Quantum nylon ripstop shell with a DWR finish, which does a commendable job fending off moisture like mist and light snowfall. I wouldn’t trust it in sustained rain or wet snow without a shell, but for its intended use as a mid or outer layer in cold, dry conditions, it holds its own. Like other jackets in the Mythic line (excluding the Mythic G), it features Nikwax hydrophobic down, which adds a welcome layer of assurance should moisture seep through—the insulation retains loft and warmth even when damp.
 

The jacket also performs admirably in the wind. During a ski tour in the Mount Baker Wilderness, I threw it on at a windswept saddle after sweating heavily on a long climb. Despite a bit of moisture build-up on the inside from my baselayer, the down stayed dry and warm, and I was comfortable again within minutes. The YKK zippers are smooth and reliable, sealing nicely to help block drafts. While the thin shell doesn’t offer true storm-level protection, the Mythic Alpine is more than capable of handling typical alpine weather when paired with a shell in more severe conditions.
 

Construction and Durability

Despite its ultralight intentions and fragile appearance, the Rab Mythic Alpine has proven impressively tough. The 10-denier Pertex Quantum ripstop nylon is predictably thin, but after a full fall and winter season of use—including skiing falls, sitting directly on snow, and general backcountry abuse—it’s remained fully intact with no tears, loose stitching, or performance hiccups. Like my past Rab pieces (jackets, shells, and sleeping bags), the build quality inspires confidence. Even after frequent stuffing alongside sharp gear like crampons and climbing skins, the jacket has held up without issue. I've only seen one feather work its way out so far, which is negligible for a down garment.
 

All components—from the YKK Vislon main zipper to the hand pocket zippers and dual hem adjusters—continue to operate smoothly. That said, this is still a lightweight jacket with a thin face fabric, and I’m careful to steer clear of thorny bushes, sharp branches, or abrasive rock. In that way, it’s similar to other ultralight puffies like the Arc’teryx Cerium or Mountain Hardwear Ghost Whisperer—durability is decent for the weight, but some care is needed. As a side note, my partner’s Mythic G, which uses an even thinner 7D Pertex shell, is in its second year of heavy use and still holding strong, albeit with some minor feather loss. All told, the Mythic Alpine walks the line between weight savings and resilience exceptionally well.
 

Key Features

True to its ultralight ambitions, the Rab Mythic Alpine keeps features to a minimum without skimping on the essentials. The hood is a good example: there are no adjustment toggles or drawcords, but the elasticized sides offer a snug fit that stays put even in gusty conditions. The malleable brim adds some structure for deflecting light wind and snow, and the tall collar reaches up to just below the lip, offering excellent coverage. Unlike Rab’s even lighter Mythic G, the Alpine’s collar is lined with a soft fleece chin guard, and a small zipper garage adds a bit of protection—though not quite as robust as what’s found on the Ghost Whisperer, which I’ve come to appreciate after a few beard-snagging moments. The hood fits cleanly over a beanie, cap, or climbing helmet, and while I’ve managed to stretch it over my Giro Spherical ski helmet in a pinch, mobility is limited. For better coverage and comfort, I prefer wearing it underneath my ski helmet.
 

As with the rest of the jacket, the pockets are streamlined but well-executed. You get just two zippered hand pockets—no chest or internal storage here—but they’re nicely insulated and sit behind the down fill, making them particularly cozy on cold days. While it’s not a feature-rich design, the Mythic Alpine offers just enough where it counts, striking a nice balance between weight savings and on-mountain usability.
 

Fit and Sizing

The Rab Mythic Alpine is offered in five standard men’s sizes from small to XXL, and features a slim, athletic cut designed with technical layering in mind. I tested a men’s large and found it to be quite form-fitting, especially in the torso—I’m 6 feet tall, 230 pounds with a 36-inch waist, and wouldn’t want to go any smaller. Those with broader waists or hips may want to try before they buy or consider roomier alternatives like the boxier Mountain Hardwear Ghost Whisperer or Feathered Friends Eos.
 

The jacket’s pre-curved arms are well-executed, offering full coverage and excellent mobility when reaching overhead or down to adjust ski boots or bindings. The cuffs overlap slightly on the tops of the hands, and the back length on my size large measures around 30.5 inches—over an inch longer than my Ghost Whisperer—providing welcome protection from drafts, and it doesn’t ride up under my shell when wearing a pack. Dual hem adjustments allow for a snug seal around the waist, and the low-profile fit layers easily under technical shells like my Arc'teryx Alpha SV and Sabre SV, as well as under my Firebee Parka on deep-winter missions. Despite its trim shape, I’ve had no trouble fitting it over a Merino base and either the Rab Tecton fleece or Arc'teryx MX Hoody, with no restriction in movement.
 

Sustainability

We love Rab for a plethora of reasons at Switchback Travel—with sustainability being one of the primary selling points. We’ve been consistently impressed by Rab’s commitment to protecting the environment, and the Mythic Alpine Jacket is a strong reflection of those values. The jacket features fluorocarbon (PFAS)-free fabric, is made with over 50% recycled materials, and is manufactured using renewable energy—all major steps toward reducing environmental impact. What really stands out, however, is Rab’s transparency: each product includes a detailed "Material Facts" table that breaks down raw data on how the product is made. It's a refreshing level of transparency that sets a high bar in the outdoor industry.
 

What We Like

• Fantastic warmth-to-weight ratio.
• Extremely comfortable.
• Strong style points.
   

What We Don't

• On the pricey side.
• Basic feature set.
• Slim fit won't work for everyone.
   

Comparison Table

*Editor's note: All listed weights are for a men's size medium

The Competition

The Rab Mythic Alpine Down Jacket is an impressive value considering the warmth it delivers, its price range, and the quality of its 900-fill down. Other competitors, such as our highly-rated Arc'teryx Cerium Hoody, offer similar levels of warmth, but feature less quality down at a slightly heavier weight. The Cerium has a more generous fit, though, which some may appreciate for layering underneath, as well as slightly beefier fabric. Patagonia's flagship Down Sweater Hoody is another wildly popular alternative in this warmth class, but features an even lower fill power and a significantly higher weight. However, Patagonia's sustainability practices, more durable 20-denier fabric, and relatively affordable price tag, make it a worthy contender for many.
 

Clocking in with a similar fill-power and weight, the Feathered Friends Eos is another premium pick in the warmth-to-weight department. The Eos' look isn't nearly as flattering as Rab's, but it offers more room to layer underneath, and has superb loft for its light weight. Finally, the Mountain Hardwear Ghost Whisperer Hoody is another popular lightweight alternative to the Rab, though it has a similarly fragile shell (10D) and lower fill-power, translating to less warmth for the weight—at a higher price. In the end, the down jacket you go with largely boils down to personal style preference and the type of conditions you plan on adventuring in.
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