Updated:
Jan 19, 2025Warmth
Weight & Packability
Comfort
Durability
Weather Resistance
Sustainability
Weight
1 lb.
Insulation
5.0 oz. of 750-fill down + synthetic
Fabric
30D nylon
Packable
Yes (stuff sack)
Pros
Cons
Arc'teryx Thorium Hoody
The Thorium is a midweight down jacket featuring 5 ounces of 750-fill down (heat mapped for efficiency) and Arc’teryx’s Coreloft synthetic insulation, which maximizes breathability and performance in areas most prone to moisture (the hood and collar). The Thorium’s longer hemline and adjustable hood are also nice features to help retain heat. The result is a jacket built to be worn as a standalone piece and is significantly warmer than popular lightweight down jackets like the Arc’teryx Cerium and Fjallraven Expedition Pack Down. On the other hand, mid-to-heavyweight jackets like the Patagonia Fitz Roy and Rab Neutrino Pro best the Thorium in warmth.
I wore the Arc'teryx Thorium during a July backpacking trip to Wedgemount Lake, British Columbia. At an elevation of over 6,000 feet, the nights were chilly and breezy, and I was glad to have the jacket for sunset explorations around the basin. But the Thorium was overall too much jacket for the summer trip, and a lighter-weight model would have served me better. I took the Thorium out again in the fall when I camped on a high ridge at 7,000 feet with temperatures around 20 degrees Fahrenheit, plus windchill. With the Patagonia R1 Pullover layered underneath, I stayed toasty despite the strong winds. This is the jacket for those who frequently get out when temperatures dip below 40 degrees Fahrenheit and want the ease of throwing on a puffy as an outer layer.
Although you’ll be plenty warm wearing the Thorium, it’s not a lightweight puffy. At 1 pound even for the women's version and a thicker-than-average 30-denier shell, it’s heavier and bulkier than other jackets in its warmth class, including the Patagonia Down Sweater (12.1 oz.; 4 oz. of 800-fill down) and Patagonia Fitz Roy reviewed here (14.8 oz.; 4.5 oz. of 800-fill down). I immediately noticed the Thorium’s weight; it was heavier than anything else in my outdoor apparel closet. And the jacket doesn’t win any awards for packability either; using the built-in stuff sack, it compresses to a somewhat disappointing size, slightly bigger than a Nalgene (I can get it smaller by using a compression sack).
Overall, the Thorium is a great option when the conditions call for it and weight isn’t so much of an issue, and it makes an excellent around-town jacket, too. But I wouldn’t want to drag it up a multi-pitch alpine climb (for that, look at the Fitz Roy or Rab Mythic G), and I’d recommend something lighter and more packable (like the Mountain Hardwear Ghost Whisperer) for warmer backpacking trips.
Wearing the Arc'teryx Thorium Hoody is nothing short of a plush experience. Fully zipped up, I feel like I’m walking around swaddled in my favorite sleeping bag: Its bulk directly translates to comfort and cushioning, the materials are soft to the touch, and the longer hem adds a nice dose of coverage. The collar is comfortable against my skin and face and the spacious and adjustable StormHood (which, unlike its predecessor, is helmet-compatible) provides additional warm and unrestricted views. Finally, although the materials are relatively thick, they are flexible enough to allow full freedom of movement.
The Throium features five pockets: two hand pockets, one internal chest pocket, and two internal dump pockets. The hand pockets are a good size and angle for keeping my hands tucked away, and the chest pocket is big enough for keys or a wallet (it also has the stuff sack connected to it with an easily detachable girth hitch). The internal dump pockets fit gloves, a beanie, or anything else you want to keep insulated—I’m a big fan of this feature in a standalone jacket. And speaking of features I love, the Thorium now has a two-way zipper, which makes life a lot easier when I’m wearing a harness.
The Thorium earns an above-average score for durability. Its 30-denier plant-based Arato nylon shell is decently thick, especially compared to jackets like the Mountain Hardwear Ghost Whisperer (10D) and the Rab Mythic G (7D). I don’t feel like I can throw the Thorium around willy-nilly (especially around abrasive rock and sharp items), but it’s robust enough to inspire confidence for typical use.
The rest of the Thorium’s materials and construction are premium. The zippers operate smoothly with no hang-ups or snags in cold temperatures. And I can attest to the brand’s reputation for durability from experience: For the last five years, I’ve owned two other Arc’teryx jackets, and they’ve netted virtually no damage (one of them had one small patched hole) even after numerous backpacking and mountaineering trips, including treks to Mt. Everest Base Camp and the summit of Mount Baker. At $500, the Thorium is one of the priciest down jackets to make our list, but at least you know your investment will last a long time.
Equipped with a PFAS-free durable water-repellent (DWR) coating and synthetic Coreloft insulation in the hood and collar, the Thorium can withstand precipitation and other moisture better than most down jackets. Several of the jackets we’ve reviewed have no DWR treatment at all (such as the Mountain Hardwear Ghost Whisperer Hoody), and the ones that do have varying degrees of effectiveness (the Rab Mythic G has a DWR coating, but it still wets out quickly). While the Thorium won’t hold up to serious rain (no down jacket will), it’ll fend off light moisture for a time: During an extended city walk in the rain, the jacket held up for the first 30 minutes; after that, it was noticeably soaked.
The Thorium also protects against wind surprisingly well thanks to its tightly woven nylon shell and lining. Compared to the Outdoor Research Helium Down (which I also tested and reviewed), it withstands much higher winds while still retaining warmth; this is high praise, given that the Helium Down features 2.5-layer waterproof fabric and markets itself as a weather-protective down jacket.
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Longevity
Choosing durable outdoor gear is perhaps the most effective way to reduce environmental impact—the longer it lasts, the less it needs to be produced. Our proprietary longevity rating evaluates overall build quality based on factors such as materials, fabric denier, component durability (including zippers and toggles), real-world performance as reported by our field testers, and our experiences with the brand.
Responsible Down Standard
The down used in this product is certified to the Responsible Down Standard (RDS). Set by The Textile Exchange, the RDS is the leading certification for sustainably sourced down in the outdoor industry. It ensures that down suppliers use sustainable land management practices, prioritize animal welfare, and provide workers with safe working conditions and fair wages. Third-party audits are conducted at all stages of the supply chain, starting with the farm supplying the down.
PFAS-Free DWR
This product’s DWR (Durable Water Repellent) finish is made without per- and polyfluoroalkyl substances (PFAS). These synthetic compounds are known as "forever chemicals” because they take an extremely long time to degrade, if at all. PFAS can eventually end up in everything from soil to drinking water and have been linked to a range of health issues.
Recycled Materials
This product is made partly or entirely from recycled materials, the most common being nylon, polyester, wool, and down. Some products include a single recycled component or partially recycled fabric, while others are 100% recycled (generally excluding accessories like zippers, Velcro, toggles, etc). Look for these details in our product sustainability report linked below.
Bluesign Approved
Bluesign Technologies, based in Switzerland, operates a third-party textile certification system that ensures materials are manufactured to strict environmental, chemical, and worker safety standards. A Bluesign-approved material indicates that it has undergone a rigorous vetting process based on the criteria above. A Bluesign Product goes the next mile, containing at least 90% Bluesign-approved fabrics and at least 30% Bluesign-approved accessories.
Responsible Manufacturing
This criterion evaluates this brand's commitment to fair wages, safe working conditions, and reducing its environmental impact throughout the production process. Responsible manufacturing is most commonly demonstrated through certifications and membership in programs such as Fair Trade Certified, Fair Wear Foundation, Worldwide Responsible Accreditation of Production, and the Fair Labor Association. We also recognize brands that prioritize local production, such as those that manufacture primarily in the United States or Europe, to reduce carbon emissions, maintain better oversight of working conditions, and comply with strict social and environmental regulations.
Recycled and/or Reduced Packaging
This brand uses recycled packaging and/or is making efforts to reduce packaging altogether. For example, it may use a certain percentage of recycled cardboard or make efforts to use less plastic across its packaging operation. In some cases, brands also use Forest Stewardship Council-certified paper products, which helps to ensure sustainable sourcing of forest materials.
Repair Services
This brand offers repair services, which can extend this product's lifespan and reduce overall consumption. Some brands offer comprehensive repair programs that can fix a wide range of issues, while others have more limited capabilities. If a brand's warranty policy only covers replacement, rather than repair, these programs usually do not meet this criterion.
Resale and/or Recycling Services
This brand has a resale and/or recycling program, which helps keep gear in circulation for longer and out of landfills. The most common form is a trade-in program, where consumers can exchange items for store credit, which is then resold. Some brands accept products back for recycling at the end of their life, thereby reducing waste. Occasionally, some do both.
Carbon Footprint Tracking
This criterion evaluates whether this brand measures its greenhouse gas emissions, along with its commitment to reduction and transparency in reporting. Typically, we require brands to follow established frameworks such as the Higg Index, Greenhouse Gas Protocol, or The Change Climate Project. Generally, companies use the widely recognized scope categorization system for measuring brand emissions.
Annual Impact Report
This brand produces and publishes an annual impact report for public consumption, tracking its environmental footprint and sustainability efforts. These reports vary in form but generally cover topics such as material sourcing, greenhouse gas and emissions tracking, waste and water usage, supply chain analysis, and packaging efforts. An impact report is an important step toward transparency and accountability on the sustainability front.
The Thorium features Arc’teryx’s regular fit. I’m usually an XL or XXL depending on the brand and how fitted I want the jacket; I tested the Thorium in an XXL, which fit true to size and left extra room for layering underneath. This model was a touch bigger than its predecessor, and roomier than the Cerium Hoody (see our Cerium Hoody review) in the same size (which features Arc’teryx’s trim fit). There’s also no constriction through the back or shoulders, allowing me to move comfortably and freely. And while the arms were a little too long for me, the elasticized cuffs helped keep them in place. The Thorium is built as a standalone piece, but I can squeeze it under my hardshell or ski jacket in a pinch—although it’s a fairly tight fit.
Patagonia Fitz Roy Down Hoody ($399): More Streamlined for the Backcountry
If you’re a weight-conscious alpine climber or backpacker facing cold conditions, the Patagonia Fitz Roy Down Hoody is a more streamlined down jacket. It weighs more than an ounce less than the Thorium and packs in similar warmth, with 4.5 ounces of 800-fill down (a loftier fill power than that of the Thorium) and a thinner 20-denier shell. It also stuffs into its pocket—a convenient feature when you’re halfway up a big wall and don’t want to pull out a stuff sack. But the Fitz Roy has disappointed us in a few ways—it doesn’t have a two-way zipper and offers very little moisture protection (no synthetic fill, hydrophobic down, or next-level fabric tech). For $100 less, it’s a lighter and more packable alpine piece, but the Thorium gets the clear edge for mixed urban and backcountry use. For more, read our review of the Patagonia Fitz Roy Down Hoody.
Arc’teryx Cerium Hoody ($400): Race-Car Sibling
If you want to go lighter and faster, consider the Arc’teryx Cerium Hoody. At just 10.2 ounces (for the women's) and with a much smaller packed size, the Cerium is one of our favorite lightweight down jackets for summer nights and shoulder-season days. It still packs in considerable warmth (3.2 oz. of 850-fill down with strategically placed Coreloft synthetic) and is one of the best jackets on the market in terms of warmth to weight thanks to its premium down, thin shell fabric, and streamlined feature set. The Cerium’s trim fit (compared to the Thorium’s regular fit) means it works well as a midlayer piece, but some will find the simple pocket layout limiting. For more, read our review of the Arc'teryx Cerium Hoody.
A standalone jacket for sub-freezing conditions that offers both urban and backcountry appeal, the Thorium boosts weather protection with a thick shell, DWR finish, and synthetic insulation in moisture-prone areas. Keep in mind the jacket is too bulky for use as a midlayer.
Warmth
Weight & Packability
Comfort
Durability
Weather Resistance
Sustainability
Named after one our our favorite mountains, the Fitz Roy is a soft and cozy mid-to-heavyweight jacket that offers efficient warmth for sub-freezing conditions. However, it lacks a few key features we look for in a belay jacket, including a long hem, two-way front zipper, and sufficiently wind and water-resistant face fabric.
Warmth
Weight & Packability
Comfort
Durability
Weather Resistance
Sustainability
The Cerium offers extremely lightweight and packable warmth for technical pursuits like alpine climbing and backcountry skiing. Its streamlined fit is ideal for layering, too. However, given the price point, thin fabrics, and trim fit, we don’t recommend this jacket for everyday use.
Warmth
Weight & Packability
Comfort
Durability
Weather Resistance
Sustainability
The Arc’teryx Thorium is a high-end midweight down jacket that functions best as a standalone piece. Its above-average warmth and decent weather resistance—in addition to a roomy fit and drop hem, internal dump pockets, and a two-way zipper—make it a great choice for technical endeavors in cold conditions (think ski touring or ice climbing). And with top-notch style and above-average durability, it’s hard to deny for around-town use. However, there are lighter down jackets that offer similar or more warmth, if you’re willing to compromise on durability. And at $500, the Thorium is not for the casual user; everyday hikers or backpackers will be better off with a lighter-weight and more affordable jacket.
maximize warmth to weight
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