Ultralight fleece is everywhere these days. You might know it as Polartec Alpha Direct Fleece, Primaloft Active fleece, Octa fleece or any number of trademarked fabrics, but it all does the same thing: insulates when layered, breathes incredibly well, and weighs virtually nothing.
But while it may look and sound like a miracle material (or several miracle materials), it has its fair share of downsides. Namely: it’s as fragile and delicate as your great grandma’s porcelain doll collection.
So before you invest in one of these high-tech performance layers for backpacking or any other kind of outdoor activity. Here’s what you absolutely need to know.
What is Ultralight Fleece?
First things first: what am I even talking about when I use the term “ultralight fleece?” Basically, it’s a category of apparel, a sub-category of fleece, that’s ultralight and designed as an insulating layer for start-stop activities like hiking, backpacking, mountain biking, even nordic skiing.
It’s so breathable it’s see-through, but long or fluffy fibers (on the inside or outside) offer insulating properties to keep you warm–but only when paired with a windproof layer like a windbreaker or insulated jacket. Indeed, for their weight, they offer excellent insulation because they trap lots of air between fibers, which keeps your warm. But again, only when layered.
On their own, or when worn over a sun shirt or base layer, they let through so much air you don’t have to stop and shed layers as frequently as you would a jacket or other fleece sweater when you’re working hard. That means you can move farther faster. I wore one on a mountain bike ride recently when it was a brisk 45ºF (I run cold) and sunny. It helps protect my arms from the breeze on cold downhills just enough but on sweaty uphills I didn’t feel the need to remove it because air flowed right through, drying it as fast as I could sweat in it.
What Ultralight Fleece Jackets are For
So when is ultralight fleece the right choice? Generally, anytime a simple, streamlined ultralight layering system is called for.
- In cool to cold temperatures when you’re active.
- During intense hikes with a variety of weather conditions.
- When participating in high-intensity start-stop activities like snowshoeing or mountain biking.
- During activities when fewer lightweight layers and breathability are key (like trail running).
- When backpacking.
- When paired with an ultralight windbreaker for a balance of warmth and breathability.
What Ultralight Fleece Jackets are NOT For
But ultralight fleece isn’t perfect for everything. Here’s when they’re not the beneficial.
- For stationary activities in the cold like campfire hangs.
- Extremely cold weather when more insulating layers are called for.
- For slow-moving activities like easy walks in the cold (unless you run hot, I guess).
- Bushwhacking.
What You Need To Know Before You Buy an Ultralight Fleece
So if you think ultralight fleece might be just the thing for the types of outdoor pursuits you like to participate in, before you buy one, there are a few things you absolutely need to understand and be OK with first.
1. Ultralight Fleece is Delicate
The first thing to know about ultralight fleece, be it Alpha Direct, Active, Octa or anything in between, is that this stuff is delicate as all get-out. But which I mean you are 100% guaranteed to rip a hole in it, snag a thread, or get it caught in your jacket zipper, probably within the first week of wear.
That’s because the knit of these materials is designed to be loose and far apart for ultimate breathability, kind of like a fishing net. That means there is ample opportunity for zipper teeth, tree branches, even your hiking buddy’s trekking pole to catch in the spaces between fibers and instantly rip a hole in your pullover. Even Velcro can do a number on light, fluffy fibers. So damage isn’t a matter of if, but when.
Two of the first ultralight fleeces I owned had either a hole or a snag after less than five wears. It’s the nature of the garment and if you’re not OK with that, do not buy an UL fleece.
2. Be Prepared to Patch or Sew
Because most of these garments are basically guaranteed to tear, you absolutely must be prepared to sew or patch them. Otherwise, you’re buying a piece of clothing that will end up either in the back of your closet never to be used again or in a landfill. Neither are sustainable–for your wallet or the environment.
So be OK with the idea that you’ll likely need to perform some repairs sooner rather than later and dust off your needle and thread.
Fortunately, most repairs are fairly straightforward and can be done while you’re sitting on the couch watching TV (learn how to darn and make other gear repairs by reading this article). I recently stitched a tear in the underarm of my Alpha Direct hoodie and it took less than 10 minutes. Don’t want to DIY? These gear repair shops will patch outdoor clothing.
3. This is not a Cozy Fleece Layer
Also important to note–especially because according to online reviews, not everyone realizes this–ultralight fleece is not the cozy layer you pull on when sitting around a campfire or trying to warm up aprés ski. These are active layers for high-output activities. They’re designed for layering while working hard, not keeping you warm all by themselves.
They’re part of a system: you wear a base layer underneath (even if that’s just a tech tee or tank top) and a windproof layer over top. That outer layer is what makes UL fleece so insulating. Without that layer trapping heat and blocking cold wind you might as well be wearing a T-shirt.
4. There are Multiple Weights of Ultralight Fleece Materials
Depending on what material you choose, there may be different weights to choose from. This gets technical fast, but suffice it to say that lighter weight fabric with lower numbers (60gsm or 90gsm) will be see-through, super breathable, and more delicate. These are the most common weights you’ll see.
Heavier weight fabrics (120gsm or 190gsm) will be less see-through, more insulating, and slightly more durable but also less ultra breathable.
5. There are Multiple Types of Ultralight Fleece Materials
While “ultralight fleece” is a catch-all term, several fabric manufacturers have designed proprietary materials that fit under that umbrella. That includes Polartec Alpha Direct, PrimaLoft Active, Teijin Octa, and Primaloft Power Dry Mesh.
Below we’ll highlight a few we’ve tested, along with a few standout features and whether we’d recommend them.
Ultralight Fleece to Try (and to Avoid)
Not all ultralight materials are created equal. They all have their quirks. Read on to decide how to choose the right ultralight fleece for you whether it’s for backpacking, hiking, cool-weather mountain biking, or any manner of fall to spring activities. These are some of the most popular and best ultralight fleece.
Polartec Alpha Direct
Polartec Alpha Direct is the original ultralight fleece. As a result, it’s the one you’ll see most often from cottage and ultralight gear makers like those on Garage Grown Gear. Brands like Squak (whom we love–use code TERRADRIFT for 15% off) offer options, as do Leve Outdoors (pictured above), Sambob and more. This is the best ultralight fleece hoodie material for backpacking in our opinion simply due to how light it is. There are also multiple weights available in this one, from an ultralight 60 to hefty 120.
Because the fibers on the outside, it’s easier to get dirty and harder to clean, say if you dribble some of your backpacking meal down the front of your shirt. It does only have a touch of stretch, but I still found it plenty easy to pull on and off.
- Features: Not as stretchy as other options.
- Durability: Delicate. Tears are common and should be expected.
- Weight: 4oz | 113g (Medium)
- Sustainability: Made of recycled materials.
Polartec Power Dry Mesh (available from Houdini almost exclusively)
My first breathable active zip-up was the Pace Flow Hoodie from Houdini, a famously sustainably-minded brand. We wore this one for years before we tried Alpha Direct because it’s not only more durable, but also designed to be recycled at the end of its life. Then we discovered the new Pace Flow 1/2 Zip made of the same stuff and liked its hoodless collar even better for layering. It’s made up of what looks like multiple layers of bubbled material with a sort of grid pattern of holes. Any stretch comes strictly from the pattern itself, not added elastane.
It is a bit heavier than some other options, but we’re OK with the trade-off for a more durable pullover, especially when it comes to hiking and less weight-restricted activities. Find the Pace Flow options here.
- Features: Moderately stretchy. Available in a full zip or 1/4 zip pullover
- Durability: More durable than average. Snags are more likely than tears.
- Weight: 10 oz | 286 g (men’s large)
- Sustainability: Circular (made of recycled materials and recyclable), Bluesign Certified.
Teijin Octa
One of the newer ultralight fleece materials to hit the scene is Octa from fabric manufacturer Teijin. I tested an Octa Hoodie from Sambob that’s made of the stuff. It’s not quite as soft on the skin as some other options, and doesn’t feel as high-end; It’s reminiscent of that team jersey fabric from high school (but not quite as cheap). It has a smooth outer face for easy layering under insulated jackets or shells (and it’s easier to wipe down when dirty) and short fluffy fibers on the cozy interior. It’s highly breathable and the fabric is a bit thicker so doesn’t feel like it will tear as easily as some other options, though we expect it will snag in time. There’s good stretch to it, which makes for easy on-and-offs and plenty of comfort while moving.
It’s also present on The North Face’s Futurefleece line (in a non-brushed, less shedding-prone option), but with a more durable outer material that’s abrasion resistant. It’s not quite as breathable as Octa on its own, but it will stand up to slightly more abuse and is available in a zip-up. We’re big fans of this TNF Summit Series Full Zip Hoodie.
- Features: Stretchy on its own, available in several forms, including fluffy fibers and lower-profile grid patterns. Insulation is on the inside.
- Durability: Less likely to tear as easily as some options with larger holes. Easier to clean the outer fabric.
- Weight: 4.6oz | 130g (medium wide)
- Sustainability: Octa on its own not made of recycled materials. SamBob is a small, inclusive cottage brand.
PrimaLoft Active Evolve
One of the newest fabrics to hit the UL scene is Active Evolve from PrimaLoft and it’s stupendously silky soft and incredibly stretchy. It’s insulating, breathable, and feels lovely on, but the fabric sheds from the minute you take it off the rack.
And because it’s made of synthetic materials, that means tons of microplastics are getting into soil and waterways every time you wear it. The shedding decreased after the first wash (I recommend using a Guppy Friend washing bag to capture microplastic particles), but I was still disappointed and wouldn’t necessarily recommend this option over the others on this list solely in the name of sustainability. Still want to try it? It’s available from Backcountry: the Highliner PrimaLoft Air-Perm Fleece in hoodie or 1/4-zip.
- Features: Stretchy, packable in an included pocket. Available in full zip or 1/4 zip pullover.
- Durability: Delicate. Tears and snags are common and should be expected after one wear. Shedding microplastics is significant.
- Weight: 6.2 oz | 187 g (men’s medium)
- Sustainability: Made of 100% recycled polyester.
Bottom Line
Ultralight fleece isn’t for everyone. In fact, it’s best suited for a relatively small group of people: those who need to move fast, keep their layers and packs light, are working hard, and have their ultralight layering system dialed in. Also: people who are willing to repair their torn, ripped or snagged apparel instead of tossing it when it inevitably springs a hole.
If that’s not you, skip the ultralight fleece and choose something more durable that doesn’t require such gentle care. Perhaps a grid fleece. If that is you, choose wisely, take care of your clothing and gear, and don’t over consume. Wander on.
