Arcteryx Mens Atom LT Hoody Nucleus


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Other colours available:
Arcteryx Mens Atom LT Hoody Black
Arcteryx Mens Atom LT Hoody Flux
Arcteryx Mens Atom LT Hoody Nereus
Arcteryx Mens Atom LT Hoody Orion
Arcteryx Mens Atom LT Hoody Nucleus
Arcteryx Mens Atom LT Hoody Shimizu

The Atom LT Hoody is a versatile, high quality lightweight insulated jacket suitable for all outdoor activities. Warm and weather resistant with air permeable side panels, it performs superbly as an outer or midlayer jacket.


Versatile high performance designs for diverse activities and conditions.


Versatile synthetic insulated mid layers with a high degree of weather resistance.


High performance, minimalist design that is durable for its weight.

Arcteryx Mens Atom LT Hoody Nucleus

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What is the Atom LT?

The Atom LT hoody is one of the best lightweight insulated hooded jackets available. This fantastic jacket can replace layers of bulky fleece with one lightweight, warm, packable layer.

What is the Atom LT made of?

Insulation: At the core of Atom you will find 60g/m² of Coreloft insulation, a synthetic insulation that is similar to Primaloft. However, it has been developed by Arc'teryx to be more durable. Not only is it more durable, but the synthetic fibres have also been siliconised to further increase breathability by reducing the fibres ability to hold onto moisture.

Face Fabric: The Tyono face fabric is a 20 denier nylon fabric that has been treated with a Durable Water Repellant (DWR) finish for greater weather protection. The tight weave of the Tyono face fabric allows for very little air permeation which plays a very important role. This minuscule amount of air will go un-noticed but will slowly replenish the warm air that's already trapped inside the insulation and will keep you at a comfortable temperature even whilst moving. To aid temperature control 100% Polyester side panels, that are super durable and have a slight bit of stretch to them, have been used to give an anatomical fit that enhances breathability and increases moisture transfer in the warm areas and also provide fantastic freedom of movement.

What are the features?

The Atom LT features two hand pockets and an internal security pocket - all of which are zipped. The hood is fully adjustable and sits snug to your head, even in strong winds. Finally, to seal out the cold, the Atom LT features a hem drawcord and low-profile Jersey knit cuffs are so soft and so smooth you'll barely notice that they are there, especially when you do need to “layer up".

How does the Atom LT fit?

The Atom LT fits into Arcteryx's 'Trim Fit' fit block, which means it is designed to sit snug to your body with room for a layer or two underneath but doesn't have lots of excess material that will flap around in the wind.

Where does the Atom LT fit in the layering system?

The Atom LT is an insulating jacket that works well as a stand-alone jacket on still, chilly days, but can also be layered up under a shell in colder, damp conditions.


It is pretty safe to say that every one of our customers that have bought an Atom LT love it; almost as much as we love ours.

  • Trim Fit
  • Moisture-resistant outer face fabric
  • Breathable
  • Insulated
  • Lightweight
  • Compressible and packable
  • Wind resistant
  • DWR finish (Durable Water Repellent) helps repel water from fabric surface
  • Composite construction
  • Breathable, stretch side panels for enhanced comfort and mobility
  • Articulated elbows
  • Gusseted underarms
  • Insulated collar
  • Full front zip with wind flap
  • Stretch-knit cuffs
  • Adjustable hem drawcord
  • Drop back hem
  • Laminated hem
  • Internal chest pocket
  • Two hand pockets
Code : 24477-NUC-

Season : 2020S R

Weight : 0KG

Sizing Information

Arc'teryx Men's Jackets & Shirts Sizing Information

Measurements refer to body size, not garment dimensions.

  Chest Waist Hip Sleeve
X-Small 36" 29" 36" 32"
Small 38" 31" 38" 33"
Medium 40" 33" 40" 34"
Large 43" 36" 43" 35"
X-Large 46" 39" 46" 36"
XX-Large 50" 43" 50" 37"
  Chest Waist Hip Sleeve
X-Small 92cm 74cm 92cm 81cm
Small 97cm 79cm 97cm 84cm
Medium 102cm 84cm 102cm 86cm
Large 110cm 94cm 110cm 89cm
X-Large 118cm 99cm 118cm 91cm
XX-Large 128cm 110cm 128cm 94cm

Next to Skin Fit: Cut snug to the body through the entire garment to enhance moisture management and thermal efficiency.

Slim Fit: Cut slim to the body through chest, waist, hip and thigh for a low profile fit.

Regular Fit: Cut comfortably from the body through bust/chest, waist, hip and thigh for a classic fit.

Relaxed Fit: Cut loosely through the waist, hip, and thigh for a casual fit.


Measure around your chest/bust, holding the measuring tape under your armpit.


Measure around your waist at the narrowest part.


From a standing position, measure from your crotch to your ankle.


With your arms in a slightly bent position, measure from the centre of the back of your neck, along the length of your arm, to the wrist.


Measure around your hips at the widest part.

Technical Information

Weight: 360g


- 100% Polyester Side Panels

- Coreloft 60 (60 g/m²)

- Tyono 20 denier shell with DWR treatment - 100% nylon


Care & Advice

How Should Your Insulated Jacket Fit?

Insulated jackets are pedantic little things. Too tight and you'll compress the insulation and limit the warmth capabilities of your brand new jacket, too loose and you'll spend hours warming up the dead space inside the jacket. Getting the correct fit isn't just about aesthetics, it will determine how warm you are. 

The Incorrect Fit

Too loose: A jacket which is too loose will keep you relatively warm, however it will take far longer to do so and will waste large amounts of your precious energy. An insulated jacket works by trapping the natural heat that your body gives off in the fibres of the insulation; this creates a micro-climate inside your jacket, keeping you warm and toasty. If your jacket is too loose, heat will be able to escape through the hem, the sleeves and the neck of the jacket; it's a little like sticking the heating on in your car with the windows cracked open - it will heat up, just incredibly slowly.   

Too tight: A jacket which is too tight is arguably worse than one that is too loose. If your jacket is far too tight, the baffles can compress to a point where the insulation can't loft effectively, limiting the amount of warmth it can trap. Essentially, it won't work! 

The Correct Fit
It's a tricky one to explain, but it's somewhere in the middle. You've first got to consider how many layers you'll tend to wear underneath; will you have just a t-shirt then the jacket, or possibly a baselayer, midlayer and then the jacket? When you've figured out your layers and you've popped your insulated jacket over the top, you shouldn't have any dead space inside. The cuffs and hem should be comfortably sealed around your waist and wrists with room to move. You should be able to lift an arm up above your head without the hem of the jacket lifting more than an inch or so, and the sleeves should be long enough that when carrying out the same motion, they aren't mid-way up your forearm. Your shoulders and chest area should have enough room so that your hands can touch behind your back without feeling restricted. 

Additional Information
Lastly, consider which activites you'll primarily be carrying out while wearing the jacket. Are you primarily using it as a winter climbing piece, or an everyday/dog walking jacket? You'll find that technical climbing jackets tend to feature a shorter cut, while urban and casual jackets feature a longer cut to offer additional warmth with less mobility.

To see examples of what a badly fitting and correctly fitting jacket looks like, click here.

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Arcteryx Mens Atom LT Hoody Nucleus

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Excellent customer service. Really detailed easy to understand product descriptions on the Trekitt website, and gear reviews on the Trekitt YouTube channel made it so easy to choose the right backpack for me.

Emily - May 2020

Amazing service! Very helpful in regards sizing and what most matched my needs, despite this being done over the internet. YouTube videos of products being examined are very useful also. Would definitely use again, very fast and efficient delivery. Brilliant! Highly recommended!

David R - April 2020

Highly recommend. I usually go to the shop in Hereford as staff are alwasy very helpful and knowledgeable. So this was the first time I have purchased online and the service was just as good as the shop.

Grizzy - April 2020

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