Arc’teryx Proton LT Review

A synthetic insulation layer that became my favorite jacket. I got this jacket three years ago, and since then it has gone on nearly every adventure, from hiking in France to backpacking in the North Cascades.

After 16 months of testing, the results are in. This is the best midlayer insulation jacket I have owned. So good that it has gone on every hike, backpacking trip, and international adventure since I got it.

Four year+ update: This jacket is now called the Proton Hoody. I still love it, and bring it on many trips, including a month kayaking and hiking in Alaska, to the Everest Basecamp, and on many hikes! Over time the synthetic insulation does lose some of its loftiness, which is typical and expected for this material. The fabric has held up exceptionally well, too!

First, this jacket is quite different from the ubiquitous Atom LT, also made by Arc’teryx. You see the Atom layer everywhere, from around town to on the trail, but the Proton LT is better in just about every way (with the exception of cost). The Proton LT is warmer, more water resistant, fits me better, and is much more durable. And I didn’t expect this, but it breathes better than the Atom as well. (Arc’teryx is releasing a revised version of the Atom jacket in fall 2020, so this comparison is to the original version).

Fit: I am 5’7 with a slim athletic build (wider shoulders and small chest). Of the Arc’teryx jackets, this one fits my frame the best. There is no excess gusseting fabric around the boobs like on the Atom, and the length is also better (it is inches longer than the Atom which always was too short).

Layering: I wear a small or medium in most brands, and a size small in this jacket allows for a mid-weight fleece and baselayer under it. It is also sleek enough that it easily fits under my other size medium puffies or shells.

DURABILITY: The face fabric on this jacket is really impressive. I hiked with it every day for two weeks in a forest in Oregon in April 2019, and many days this involved walking through, over, and around downed trees. I would catch the jacket on a branch and expect it to be torn, only to look and see no mark at all. Super impressive. After some run-ins with rocks in the cascades and sandstone in Utah it also shows no signs of abrasion. It is also worth noting that this fabric resists stains much better than others I’ve used. I’m an outdoor watercolor painter, and routinely get paint on the jacket. Even after leaving the paint stains on the jacket for weeks during a trip, the pigment washed right out with a little bit of hand soap. The same for sunscreen or makeup marks. (note: the paint color was a grey-brown mix. If I had gotten my super staining Phthalo blue on it, it likely would not have washed out, as that color stains everything).

Pockets: three outside pockets, two on the sides and one chest. Side pockets do not interfere with a hip belt, and the chest pocket is big enough for my Iphone 11 in a bulky case. Related to pockets are the great cuffs, which even after a year of heavy use haven’t lost their shape and have zero pilling. 

Color: I got the beautiful Sunhaven color, and I get so many compliments on it and it looks great in photos.

To make something awesome even better, I would love to see the next version have a little bit more robust draft tube: on a 16*F and really windy day my face got a bit cold through the zipper while skiing uphill. Everywhere else was warm and happy. Keep this in mind if you are someone who relies on your fully zipped jacket to protect your neck/ face in cold conditions, as I had to add a buff beneath it for better warmth.

Lastly, the face fabric has some impressive fire-retardancy. I skied into a remote mountain hut, and during dinner leaned back into a candle that had been accidentally moved too close without me knowing. Exposed to an open flame, 2 sq inches of the the exterior fabric charred and melted but did not catch on fire, saving me from a possible really bad burn. The heat was intense enough to melt the inner layers. Arc’teryx was unable to repair the burn and sent me some Tenacious Tape to make the repair. After carefully cutting out the stiff melted areas I applied tape to the outside and inside of the hood, and it is holding up great months later after multiple washing (please note that Arc’xteryx made an exception to their usual repair policies and let me have the jacket back, as I was a local ambassafor for the Seattle store at the time. Normally they do not want damaged goods in circulation).

Three-years later review:

I’ve now had this jacket for three years. I liked it so much that when Arc’teryx was not able to repair the original I had the chance to buy another discounted, and jumped on the chance. My second one is in a lovely dark maroon color.

Having two to compare was really useful, to see the wear on the garment. The face fabric of the original jacket still looked perfect, an impressive feat. The one thing I did notice, however, was that after three years of heavy use the insulation in the old one is noticeably more compact than the new garment. This is expected, and happens with every synthetic-fill jacket because the fibers simply do not have the same lofting resiliency of down. I also used my old jacket as a pillow while backpacking, and I think that may have contributed to some unnecessary compression. I now have a lightweight pillow from Sea to Summit that works way better.

The Proton LT remains my favorite jacket that I reach for throughout the year. It is still so versatile, and the best fitting jacket I own.

Disclaimer: I occasionally test gear for the Arc’teryx Seattle store and was given a sample of this jacket 6 months before its release. With that said, I only recommend products that I would purchase myself. As of March 2021 I am also a local ambassador for the Seattle store. I will, however, always provide truthful reviews regardless of whether I pay full price or not for an item.