After years of wearing the Abercrombie & Fitch Wolf Jaw hoodie as my winter jacket, I figured it was time for a change. If you can say anything about the Wolf Jaw, while warm it’s incredibly heavy coming in at around 5 lbs. In typical “grass is greener” fashion, I wanted something on the opposite side of the weight spectrum – ultra light but still warm. Basically I wanted my cake and to eat it too.

Typically when one thinks of winter coats and jackets, brands like The North Face, Patagonia, Marmot, and Canada Goose dominate mainstream mind-share. I wanted something slightly off the beaten track and since I’ve always been pleased with the quality and longevity of my Under Armour workout gear, I decided to approach UA’s offerings with an open mind. Enter the Coldgear Reactor jacket.

Now I can hear the eyebrows of outerwear enthusiasts raising all across the interwebs as one typically wouldn’t cross shop UA’s Reactor jacket with something like the TNF Summit L3.  The former attempts to balance warmth with breath-ability for activities such as outdoor running and snowboarding while the latter is geared for the back country, alpine climber demographic. But from the perspective of the “normal dude” demographic, I’m just trying to keep warm without being bogged down from excess weight and bulk.

The Coldgear Reactor jacket is very light at 13 oz (or 368 grams) and purportedly will regulate your body temperature by insulating when you are stationary but dump excess heat when you are active. While the exact mechanism is unclear, The North Face has a similar Ventrix jacket that achieves this via a synthetic material with micro-pores that “open” or “close” depending on movement. While the A&F Wolfjaw hoodie is plenty warm when outside, it’s far too hot to wear inside for any extended period of time, which means I inevitably end up carrying an awkwardly sized, heavy jacket throughout the market, mall, or whatever indoor venue I’m visiting.

First Impressions

My first impression of the Under Armour Coldgear Reactor jacket was skepticism; how could something this thin and light offer any amount of warmth above and beyond a typical windbreaker? The 2018 version has ditched the MagZip (Under Armour’s proprietary magnetic zipper mechanism) that was present on the jacket in previous versions. Reading through past reviews it seems while convenient to use, the MagZip was notoriously prone to breakage so it seems like UA quietly ditched it this time around. The Under Armour logo is also a muted gray as opposed to a stark white – a good change – as the previous version was a little too loud for my tastes.


The medium Reactor jacket provides a flattering fit with a slight but noticeable tightness in the shoulders and lats, especially during twisting motions. It’s by no means restrictive nor is there any danger of ripping the jacket’s inner lining (which actually happened to me with the XL Wolfjaw) so it’s just something worthy of note.

The sleeves are cuffed with a moderately stretchy material allowing for roughly 3 inches of play when fully stretched.

The collar can be a bit of a nuisance as I found it constantly fighting with my lower jaw for space. This is the least comfortable aspect of the jacket as it never really “disappears”. 


The front of the jacket tends to wrinkle a bit which detracts from what should be a sleek black shell.

When sitting down, the front abdomen area settles into a small but unsightly bulge, as if one had an alien chest buster emerging. Again it’s a minor nitpick and very much “first world problems”, however again it’s worth noting. Overall I would rate the aesthetics 8/10 as overall it provides a flattering fit but with minor nitpicks during real-world usage.


The Reactor jacket has two handwarmer pockets with zippers and an exterior chest pocket, which is new for 2018. The fact that the hand pockets are fleece-lined is a nice touch (pun intended). Within the pockets there’s also drawstrings to tighten up the “skirt” area. The jacket is very packable, and can be compressed down into the chest pocket.


I compared the UA Coldgear Reactor jacket with the North Face’s Summit L3 Down Hoodie, which OutdoorGearLab rates as 2018’s best men’s winter jacket.

The Reactor jacket has 80g of proprietary synthetic insulation in the body and 60g in the sleeves, while the Summit L3 is goose down of the 800-fill power variety.

In comparison, the Reactor jacket is not quite as warm, but is more suited for athletic activity. The Summit L3 is quite a bit loftier, has better coverage and comfort in the neck/chin area, and also has an excellent hood. 

As of 3.6.2019 the MSRP on the UA Coldgear Reactor jacket is $120 USD (albeit with limited, “end of season” color choices) while the TNF Summit L3 Hoodie is $350 and only available in “shiny” colorways.

With layering, the Coldgear is usable down to 20° F while the Summit L3 works down to 10° F.

Final Thoughts

For those who live in warmer climates without a true winter, the Reactor jacket is more than enough. For winters in the Midwest or North East, you’ll also need an extra heavy winter coat for the coldest periods of winter.

I took the Under Armour Coldgear Reactor jacket as my only piece of outerwear to Las Vegas in February where the temperature ranged between 30° – 60° F. It served admirably throughout, and zipping it up or down provided all the thermal regulation needed.

When zipped up, the Reactor jacket also completely blocked the wind, of which there was quite a bit during my stay. Overall I would consider the Reactor jacket perfectly fine for all but the coldest of winters.

Under Armour isn’t really known for their outerwear, but it’s apparent they are trying to break into the market. They definitely have a sleeper product on their hands with the Coldgear Reactor jacket.