Arc’teryx Atom Hoody vs Atom SL | 2024 Review & Comparison

The Arc’teryx Atom Hoody and Atom Jacket may very well be Arc’teryx’s best-known product line, and for good reason. For more than 15 years the Atom has deftly blended performance, comfort and style, winning over customers with its durability and versatility. In 2023, the Atom LT underwent a name change, becoming simply the Atom Hoody and Atom Jacket in both men’s and women’s versions. The Atom SL is now the Atom Lightweight in the women’s version but is still called the SL in the men’s version - at least for now. 

Naming convention aside, what hasn’t changed are the things that continue to make the Atom Hoody and Atom Jacket, in all its iterations, one of our favorite Arc’teryx products: high-performance synthetic insulation that works as either a midlayer or outer layer for both casual wear and higher-output activities. But with three versions - Atom Heavyweight (formerly called the Atom AR), Atom, and Atom SL/Atom Lightweight - to choose from, it’s important to understand their differences as well as the ideal uses of each. 

In this review, we take a closer look at the Atom (LT) vs Atom SL/Atom Lightweight. If you're debating between the Atom (LT) and the Atom Heavyweight, we compare them here: https://outdoorcrunch.com/atom-ar-vs-atom-lt/.

Bottom line: The Atom Hoody is a versatile and comfortable midweight insulated jacket that provides a winning combination of warmth and breathability during colder weather. The Atom SL (men's) / Atom Lightweight (women's) Hoody takes a more minimalist approach, making it a more breathable but significantly less warm option for high-output activities during chilly spring and summer outings. If you want a fall, winter and spring performer, go with the Atom. If you need something to keep you warm during chilly spring, summer and early fall outings, opt for the Lightweight/SL.    

Before we get any further, here’s how Arc’teryx compares the two: https://arcteryx.com/us/en/compare/X000007487/X000005409

And one of our favorite tools is Arc'teryx's jacket finder: https://arcteryx.com/us/en/shop/jacket-finder

Warmth

Again, the Atom (LT) Hoody is clearly the warmer option as compared to the Atom SL/Lightweight Hoody, and it’s not really close. There are three factors that make the Atom warmer than its SL/Lightweight counterpart:

1. The Atom Hoody uses Coreloft 60 insulation, versus the Coreloft Compact 40 insulation of the Atom SL/Lightweight. 

   The Coreloft Compact 40 g/m2 found in the Atom SL/Lightweight is Arc'teryx's lowest density (1.2 oz/yd2) Coreloft insulation. The only two Arc'teryx jackets insulated with 40 gsm Coreloft are the Atom SL and the Proton Hybrid (Men's - Women's - read review).
   
   The Proton Hybrid is much newer (released for fall/winter 2022 but not currently available on Arctyeryx.com). Before that, the Atom SL was long the only holder of this title. This is also one of the factors that makes the SL exceptionally light, especially compared to the Atom (9.5 ounces/269 grams vs 13.1 ounces/370 grams). The Atom's Coreloft 60 g/m2, on the other hand, makes it more insulated and warmer but also heavier. Is the 100-gram difference significant for you and your needs?

2. The Atom Hoody is insulated throughout, whereas the Atom SL/Lightweight is insulated only through the body’s core

   That’s right, the Atom (LT) Hoody and Jacket are insulated everywhere - body, sleeves and hood. The Atom SL/Lightweight, on the other hand, is insulated only through the chest and back. Think of it kind of like an insulated vest with windbreaker sleeves and hood. The sleeves of the Atom SL/Lightweight are mesh lined beneath their Tyono 20 nylon exterior. This difference obviously results in a significant warmth disparity between the two models. 

3. The Atom (LT) Hoody has a looser fit than the Atom SL/Lightweight

   As a result, the Atom (LT) Hoody is able to trap more air between the jacket and your body, which adds to the insulating effect. The Atom also offers two hem adjustment drawcords to the Atom SL/Lightweight’s one, making it easy to cinch the hoody to prevent heat escape and unruly wind drafts. 

Our extensive temperature ratings of Arc’teryx jackets, including the Atom series, is below:

Breathability & Ventilation

The Atom line is famous for its breathability, but it varies between models. The Atom (LT) Hoody is extremely breathable, but the Atom SL/Lightweight is even more so. We’ll explain.

Unlike the Fortius Air face fabric of Arc’teryx’s Proton line, the Atom line does not use highly breathable face fabrics. Instead it uses Tyono, a nylon fabric. We compare the Atom to the Proton here: https://outdoorcrunch.com/arcteryx-proton-vs-atom/

But face fabric is only one variable of breathability. The other, and possibly more significant factor, is mechanical ventilation. This is where the Atom’s side fleece panels come in and work spectacularly. 

The stretchy fleece panels placed along the sides of the Atom (LT) Hoody and Atom SL/Lightweight help prevent overheating by dumping excess heat. Think of them as pit zips on steroids. They're also great for mobility no matter your activity, stretching and moving with your body.

And while both the Atom (LT) and Atom SL / Atom Lightweight feature these fleece panels, the size difference of the panels between the two models is significant and therefore makes a noticeable impact on breathability. The quality of the fleece is different as well, with the Atom (LT) using noticeably heavier weight fleece as compared to the lighter fleece panels of the Atom SL/Lightweight. 

Let's first take a look at the side fleece panels of the Atom SL/Lightweight. Note how the fleece runs all the way from the hem to the cuffs. 

Now here are the Atom LT’s side fleece panels, which extend only from the hem to the armpit but are also about an inch wider than the Atom SL/Lightweight’s panels. 

The first time I wore these jackets, I guessed that the wider panels of the Atom would even out the longer panels of the Atom SL/Lightweight, and in the end provide equal ventilation. But that’s not the case. In reality, the added breathability of the Atom SL/Lightweight from the extended fleece panels is readily apparent, which is a good or bad thing depending on how you plan to use your jacket. Personally, I’m a fan of the breathability, especially when I’m using my Atom SL for high-output activities in the spring and fall.  

Weather resistance

Conversely, those big side fleece panels come with a cost: reduced weather resistance. When the wind is blowing, both models invite the wind inside. A lot. This can be a good thing if your output is high or if you naturally run warm. But when you don't want the wind in, there's nothing you can do about it. 

This is what makes the Atom SL/Lightweight much more of a niche product. When comparing the jacket's breathability to its wind resistance, the Atom SL leans way hard on the breathability end of the spectrum. 

The Atom (LT), on the other hand, is more balanced, even with its own fleece side panels skewing toward breathability. 

Both models of Atom will repel a moderate amount of moisture for a short period of time, but they are absolutely not waterproof. The Tyono 20 denier nylon face fabric is treated with a FC0 DWR finish on both the Atom (LT) and the Atom SL/Lightweight models. We’ve been impressed with their ability to shed precipitation, but they will eventually soak through. If you’re expecting sustained precipitation, bring a waterproof shell as an outer layer.

Fit

As mentioned in the Warmth section above, the Atom (LT) Hoody and Jacket feature a slightly looser fit than the Atom SL/Lightweight. We would describe the Atom SL/Lightweight as fitted, while the Atom (LT) is between fitted and regular. 

The fit differences underscore the differing uses of each model. The Atom (LT) can be used year-round as both an outer layer or midlayer, with the fit being sufficient to go on top of a baselayer as well as underneath an outer layer. The Atom SL/Lightweight is a spring/summer/fall piece for higher-output activities or when you just barely need some additional warmth for comfort.

Pockets

Both models have two handwarmer pockets with hidden zippers. The pockets on the Atom (LT) are fleece lined on one side and nylon on the other, while both sides of the pocket are nylon only on the Atom SL/Lightweight. 

Only the Atom (LT) has an internal zippered chest pocket, which is appropriately sized for stashing your phone, credit cards, key or other smaller items. 

I also prefer more pockets to fewer pockets, so the Atom (LT) wins out in this area.

Hood

The Atom (LT) Hoody has an insulated and adjustable StormHood that is large enough to maybe fit over some climbing helmets but won’t fit over a ski helmet. The hood is not removable or stowarble

The StormHood on the Atom SL/Lightweight is non-insulated nylon. It is adjustable with a single pull cord at the back of the hood, and it has a close-to-the-head fit that will not go over any type of helmet. We appreciate the shaped visor that provides structure to the front of the hood above your eyes, and we also like that the hood is stowable - meaning you can roll it inward and use the attached button to form it into a collar.

Cuffs

Both the Atom (LT) and Atom SL/Lightweight have stretch cuffs, but they’re executed differently. The cuff on the Atom (LT) encircles the entire wrist (see photos), while the cuff on the Atom SL/Lightweight incorporates the edge of the fleece side panel on the inside of the wrist and the hemmed Tyono face fabric on the outside of the wrist. 

Both are functional and comfortable; it becomes just a personal preference.

How to wash your Atom Hoody

Arc'teryx recommends washing your Atom Hoody with Nu Down Detergent, and then using Nu Durable Water Repellent to reapply the DWR finish to your jacket. Here are step-by-step directions:

When to wash

• Heavy use (e.g. running, ski touring) – wash every 10 to 12 days of use

• Light use (e.g. dog walking, casual wear) – wash every 20 to 30 days of use

If your Arc'teryx jacket looks dirty or is no longer beading water, it’s time to give it a wash and re-apply DWR.

How to wash

• Close the jacket's primary zipper.

• Open the pocket zipper and ensure all items are removed. Leave the pocket zippers open.

• Release the tension on all elastic drawcords.

• Place your Atom in the washing machine and add cleaning detergent as indicated on bottle. 

• Wash on medium cycle heat (40C/104F) using a permanent press or gentle cycle setting. 

• Run a second rinse cycle to remove any residual soap. 

How to dry

• Place your damp Atom in the dryer on medium heat for 40-50 minutes. This will reactivate the jacket's DWR. 

• Re-apply DWR finish if needed. How do you know whether it's needed? Test your clean and dry garment with a light spray to see if water beads off the surface. If water is not beading off your jacket, re-apply a DWR treatment.

Arc'teryx does not recommend using a wash-in DWR treatment because it doesn't guarantee an even application over the entire surface of your jacket. Instead, use a spray-on DWR finish.