Arc'teryx Epsilon vs. Atom: Which one is better? [2026]

The Arc'teryx Epsilon is a highly weather-resistant softshell designed for active use, prioritizing windproofing and water resistance over insulation. In contrast, the Arc'teryx Atom Hoody is a legendary insulated jacket that excels at providing warmth and breathability, making it one of the most versatile mid-layers available from the Arc'teryx brand.

Here's everything you need to know to decide whether the protective Epsilon shell or the insulated Atom mid-layer is right for you.

Arc'teryx Epsilon Hoody

The Epsilon Hoody is a technical softshell that acts as a formidable barrier against the elements. It’s designed for high-output activities where wind, light rain, or snow are a concern but a full hardshell is too cumbersome. Its strength lies in its excellent weather resistance combined with a high degree of stretch and breathability, allowing you to move freely without overheating.

• What it is: A weather-resistant, air-permeable softshell jacket designed for active use and layering.
• Key features: GORE-TEX INFINIUM™ fabric for complete windproofing and high water resistance, fleece backer for light warmth, helmet-compatible hood, and articulated patterning for mobility.
• Price: Around $299
• Materials/Construction: The main material is a durable GORE-TEX INFINIUM™ face fabric bonded to a gridded fleece backer, providing durability and a bit of warmth.
• Sizing/Fit: A trim, athletic fit that layers cleanly over a base layer or light fleece while sitting comfortably under a heavier outer jacket or harness.
• Pros: Exceptional wind protection, highly water-resistant for most conditions short of a downpour, excellent breathability for a protective shell, durable face fabric.
• Cons: Offers very little insulation, not completely waterproof, and has a premium price for a softshell.

This jacket is perfect for hikers, climbers, and backcountry tourists who need a durable and reliable outer layer for protection in cool, windy, and damp weather.

Shop this product: arcteryx.com/us/en/shop/mens/epsilon-hoody

Arc'teryx Atom Hoody

The Atom Hoody is widely considered one of the most versatile pieces of outdoor gear you can own. It functions as a warm, breathable mid-layer for cold-weather pursuits or as a perfect standalone jacket for cool, dry conditions. Its Coreloft™ insulation retains warmth even when damp, and stretch fleece side panels dump excess heat during activity, making it adaptable to a huge range of temperatures and effort levels.

• What it is: A lightweight, synthetically insulated hoody for use as a mid-layer or standalone jacket.
• Key features: Coreloft™ Compact synthetic insulation provides warmth and retains loft, Tyono™ 20 face fabric with a DWR finish repels moisture, and fleece stretch side panels improve ventilation and fit.
• Price: Around $300
• Materials/Construction: Built with a lightweight and durable Tyono™ 20 nylon shell, Coreloft™ insulation in the body, arms, and hood, and gusseted side panels made of performance stretch fleece.
• Sizing/Fit: Features a trim but regular fit designed to comfortably layer over a base layer and fit easily under a shell. Many find it true to size.
• Pros: Excellent warmth-to-weight ratio, exceptionally breathable for an insulated jacket, insulation works when wet, extremely versatile across seasons and activities, lightweight and highly packable.
• Cons: Only water-resistant, not waterproof, the lightweight face fabric is less abrasion-resistant than a dedicated shell.

It’s the ideal choice for an all-around insulated jacket that works for nearly everything, from an ascent in the mountains to morning coffee runs in the city.

Shop this product: arcteryx.com/us/en/shop/mens/atom-hoody

Arc'teryx Epsilon vs. Atom Comparison

Warmth & Insulation

This is the most significant difference between the two jackets. The Arc'teryx Atom Hoody is an insulated jacket, purpose-built to provide warmth. Its Coreloft™ insulation is designed to keep you warm across a wide range of conditions, effectively acting as your portable heater.

The Arc'teryx Epsilon Hoody is a shell with almost no insulation. While its bonded fleece backing offers a tiny bit of warmth compared to a thin hardshell, its primary job is to protect you from the elements, not to generate warmth. It's designed to be worn over insulating layers, not to serve as one.

Weather Protection (Wind & Water)

The Epsilon holds the advantage in weather protection. Its GORE-TEX INFINIUM™ fabric makes it fully windproof and highly water-resistant, capable of shedding light to moderate rain and snow for extended periods. It is the superior choice when wind and drizzle are the main challenges.

The Atom Hoody is merely weather-resistant. Its Tyono™ face fabric has a DWR (Durable Water Repellent) finish that will bead up light moisture, but it will wet-out in sustained rain. While it offers moderate wind resistance, it doesn't provide the near-impenetrable barrier that the Epsilon does.

Breathability & Activity Use

Both jackets are engineered for high-output activities and are highly breathable. The Atom achieves this with its air-permeable materials and strategically placed stretch-fleece side panels that allow heat and sweat to escape efficiently. This makes it fantastic for stop-and-go activities like hiking or climbing where you need warmth at rest stops but don't want to overheat on the move.

The Epsilon’s GORE-TEX INFINIUM™ membrane is also extremely breathable, especially for a weather-resistant fabric. It excels during consistent-effort activities like backcountry touring, snowshoeing, or fast-paced hiking in unpleasant weather, where it effectively manages moisture from the inside while blocking elements from the outside.

Versatility

While the Epsilon is a master of its specific domain - active use in windy and damp conditions - the Atom Hoody is the clear winner in all-around versatility. It can be worn as a comfortable outer layer on cool, clear days, a technical mid-layer for skiing or ice climbing, or even a casual jacket for daily errands. Its blend of warmth, breathability, and comfort makes it an adaptable piece for three-season use and a winter layering essential.

Which One Should You Choose?

Both jackets are excellent, but they are designed for fundamentally different purposes.

Choose the Epsilon Hoody if:

• You need a primary windproof and highly water-resistant outer layer.
• You prioritize weather protection and durability.
• Your activities often take place in windy, cool, and drizzly conditions.
• You already have a system of insulating layers (like a fleece or an Atom) to wear underneath it.

Choose the Atom Hoody if:

• You are looking for one of the most versatile jackets you can buy.
• You need a piece that provides efficient insulation and breathes well during activity.
• You want a jacket that works as a standalone piece in cool weather and as a mid-layer in cold, wet weather.
• You need a lightweight, packable jacket for warmth during travel and backcountry adventures.

Frequently Asked Questions

What's the main difference between the Arc'teryx Epsilon and Atom?

The main difference is their function. The Epsilon is a weather-resistant softshell designed to protect you from wind and light rain. The Atom is a synthetically insulated jacket designed to keep you warm.

Is the Arc'teryx Epsilon waterproof?

No, it is not fully waterproof. It is built with GORE-TEX INFINIUM™, which is highly water-resistant and can handle light to moderate rain and snow, but its seams are not taped and it will not handle a sustained downpour like a GORE-TEX hardshell will.

Is the Arc'teryx Atom warm enough for winter?

As a standalone jacket, the Atom is best for mild winter days or high-output activities. For very cold temperatures, it works best as part of a layering system, worn under a waterproof or windproof shell like the Epsilon or a hardshell.

Which jacket is more versatile?

The Arc'teryx Atom Hoody is significantly more versatile. Its ability to function as both a standalone jacket and a technical mid-layer makes it useful in a far greater range of temperatures and situations than the more specialized Epsilon.

Can I wear the Atom under the Epsilon?

Yes, absolutely. Wearing the Atom Hoody under the Epsilon Hoody creates an excellent, highly modular system for cold, windy, and damp conditions, combining insulation with top-tier weather protection.

How do the Epsilon and Atom fit?

Both jackets feature Arc'teryx's trim, athletic fit. They're designed to be close to the body for thermal efficiency and to eliminate extra bulk, but they still allow for excellent freedom of movement. Most people find they take their regular size in both.

How do I know which one to choose for hiking?

For hiking in cold, crisp, and dry conditions, choose the Atom for its warmth and breathability. For hiking in windy weather with a chance of showers, choose the Epsilon for its superior weather protection.