arcteryx and patagonia

At the bottom of this post, find my blueprints and complete guides to best Arc'teryx jackets and best Patagonia jackets.

Overview

The advantages Nano Puff has over Atom LT is that it:

• Is more weather resistant,
• Comes with and stuffs into its own sack (Atom LT doesn't come with one),
• Is slightly lighter {363 grams (12.8 ounces) vs 415 grams (14.6 ounces)}

Now you understand why Nano Puff is a really popular jacket around traveler folks, and also why it's one of my top synthetic insulated jacket for travelers.

Atom LT, on the other hand,

• Is much more breathable (because of its famous side fleece panels), 
• Is more comfortable,
• And looks better (at least to me - especially this Orion color with Flux interior). 

So, in summary, if you'll be using the jacket both in the town & during high output activities, then your jacket is probably Atom LT (if, for some reason, Proton LT isn't an option for you). If you'll mostly be traveling with the jacket and won't be physically active with it, then Nano Puff would probably be a better choice.

Lastly, do not get either of these jackets if you'll be out in below 30 deg F (0 deg C) a fair amount of days - because you'll quite likely to feel chilly inside them (assuming no substantial under layering - just a long sleeved shirt) unless you run much warmer than the average person.

Different insulation materials

Atom LT's Coreloft is made with highly crimped multi-denier siliconized polyester yarn. Its lightweight, breathable and thermally efficient 100% polyester staple fiber is compressible and has good loft retention. Comes in the following six weights:

1. 1.2 oz/yd2, 40 g/m2,
2. 1.8 oz/yd2, 60 g/m2 (the density Atom LT uses),
3. 2.4 oz/yd2, 80 g/m2,
4. 3.0 oz/yd2, 100 g/m2,
5. 3.5 oz/yd2, 120 g/m2,
6. 4.2 oz/yd2, 140 g/m2.

So how do these different insulation techniques play out when using these jackets? 

Breathability

Atom LT's 60 g/m2 is the higher breathability / less warmth region for Arc'teryx's jackets. 60 g/m2 also compromises weather resistance to achieve more stretch and comfort.

The main advantage you'll have with the Nano Puff's 60 grams of Primaloft Gold Insulation Eco over Atom LT's 60 g/m2 Coreloft, on the other hand, is that it's more compressible (which is why it comes with a stuff sack) and provides superior wet-weather performance.

But insulator difference isn't the main thing that makes Atom LT more breathable than the Nano Puff.

Atom LT's side fleece panels

The game-changer here is actually Atom LT's side fleece panels.

If you're having a dilemma between these two jackets, then you should have heard of these panels before already - they're admired by many users.

First I want to say that using fleece panels with the intention to make a jacket more breathable is considered outdated in today's outdoor gear world. 

The reason is that there has been a lot of advanced breathable insulators released into the market. Jackets made with genuinely breathable materials such as Arcteryx's Proton LT and Patagonia's Nano Air started to take the lead.

But there are many climbers and skiers still using jackets with side fleece panels today. My, too, first choice would be Proton LT as you can see here when it comes to choosing a jacket for a combination of casual and active use - but Atom LT is a good alternative.

Needless to say, Nano Puff doesn't offer side fleece panels.

Warmth

I'd say, generally speaking, when it's dry out, with only a long sleeved shirt under and without a shell on top, with a mild wind and very low to no activity level...

The approximate lowest temperatures an average person can wear these jackets without feeling cold would be around 30 deg F (0 deg C).

Like I said earlier, they provide about the same warmth as you see. If you think you run hotter or colder than the average person, then shift this temperature {30 deg F (0 deg C)} accordingly.

When there's anything more than a light rain, though, Atom LT's performance will drop slightly below Nano Puff's.

Which brings me to my next point...

Different face fabrics

This factor will play out in durability, comfort and weather resistance. 

Although side fleece panels of LT make it much more breathable, it inevitably compromises wind resistance in return significantly. Wind will cut right through it. 

You can solve this by under layering an Atom LT with a wind-shirt. But that requires extra effort from the buyer's side, so I'd write minus points for Atom LT in this department.

The fabric of Nano Puff (Shell: 1.4-oz 20D 100% recycled polyester, Lining: 1.3-oz 22D 100% recycled polyester) isn't any better than that of Atom LT (Tyono 20D / Polartec Power Stretch), but it isn't equipped with side fleece panels, it certainly isn't THAT vulnerable against strong winds. 

Both are DWR coated.

Gentle, smooth, stretchy inner surface of Atom LT provides much more comfort than Nano Puff. This is especially important when you're active with the jacket.

Slightly more robust outer shell of Nano Puff is slightly more durable than Atom LT's stretching fabrics which is intended to increase comfort during high output activities.

But still, the Nano Puff won't be able to counter an abrasion caused by a stiff or pointy rock when climbing either, just like Atom LT. I wouldn't say they're much different than one another when it comes to durability.

Conclusion

So, in summary, if you'll be using the jacket both in the town & during high output activities, then your jacket is probably Atom LT (if, for some reason, Proton LT isn't an option for you). If you'll mostly be traveling with the jacket and won't be physically active with it, then Nano Puff would probably be a better choice.

I'd recommend both products WITH the hoody. 

Proton LT and Atom LT are revised for FW23.

New product pages (women's counterparts have been undergoing a naming scheme change, but it doesn't affect the product designs): 

• https://arcteryx.com/us/en/shop/mens/proton-lt-hoody
• https://arcteryx.com/us/en/shop/mens/atom-lt-hoody
• https://arcteryx.com/us/en/shop/womens/proton-hoody
• https://arcteryx.com/us/en/shop/womens/atom-hoody
• https://www.patagonia.com/product/mens-nano-air-hoody/84366.html
• https://www.patagonia.com/product/womens-nano-air-hoody/84267.html
  
• See the side by side comparison of Atom LT vs Proton LT:  https://arcteryx.com/us/en/compare/X000004842-distortion/X000005160-oracle 

Summary

My take is that these products are much more similar than they're different. The differences in things like warmth and breathability which I'll shortly be laying out might not even be that noticeable to you. 

So I'd base my decision primarily on my preference around the pocket configuration. Atom LT doesn't come with an external chest pocket, but an internal one. Proton LT and Nano Air both offer one chest pocket. 

Second, I'd take a look at the products and see which one looks more to my taste. 

Third, I'd compare the brands rather than the models. 

But if you STILL can't decide, then to maximize warmth and weather resistance, I'd pick Proton LT. To maximize breathability, I'd pick Atom LT. To maximize comfort, lightness and packability, pick I'd Nano Air. 

To find out more about these jackets, check out this chart: 

Also see: 

• https://outdoorcrunch.com/arcteryx-proton-lt-vs-atom-lt/
• https://outdoorcrunch.com/arcteryx-proton-hybrid-hoody-review/
• https://outdoorcrunch.com/atom-ar-vs-atom-lt/
• https://outdoorcrunch.com/arcteryx-atom-lt-vs-sl/
• https://outdoorcrunch.com/atom-sl-vs-proton-fl/

Breathability

Although Atom LT delivers the membrane with the least breathable of these 3, it certainly still offers the most total breathability of all because of its mesh ventilation panels located at the arm pits. 

Mechanical ventilation will almost always be a superior parameter than membrane breathability. 

Warmth & Weather Resistance

Side fleece panels of Atom LT become a disadvantage when it's cold, windy and/or rainy. They'll let some foul weather in. 

On top of that, Proton LT offers 80 gsm of Coreloft reinforcements in strategical areas such as the hood, in addition to 60 gsm in the body. Atom LT, on the other hand, is equipped with 60 gsm everywhere, without any reinforcements.

This makes Proton LT the warmest of all. 

When it comes to weather resistance, Proton LT again takes the lead thanks to its stiffer and relatively more robust face fabric. Nano Air is the most fragile of all, so it's going to offer the least amount of weather protection in this regard. Not only against precipitation but also against wind. 

Also, all these jackets are DWR coated. 

Packability

Air is packable whereas the Atom LT and Proton LT aren't. 

Links:

• https://arcteryx.com/us/en/shop/mens/proton-lt-hoody
• https://arcteryx.com/us/en/shop/mens/atom-lt-hoody
• https://arcteryx.com/us/en/shop/womens/proton-hoody
• https://arcteryx.com/us/en/shop/womens/atom-hoody
• https://www.patagonia.com/product/mens-nano-air-hoody/84366.html
• https://www.patagonia.com/product/womens-nano-air-hoody/84267.html
• See the side by side comparison of Atom LT vs Proton LT:  https://arcteryx.com/us/en/compare/X000004842-distortion/X000005160-oracle