Best Synthetic Insulated Jackets 2023 - Outdoors Magic

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Down and Insulated Jackets

Best Synthetic Insulated Jackets 2023

Synthetic insulated jackets offer reliable warmth in wet weather, compressibility and a long-lifespan. Here's what to look for and the best options out there.

The best synthetic insulated jackets are those that are dependable and that will see you through the rough stuff. The first synthetic insulated jacket that I purchased did just that. It was a Mountain Equipment Fitzroy Jacket and it was one hell of a thing. Fit to burst with PrimaLoft insulation, it lived in the bottom of my climbing pack only to be pulled out during cold, wet and windy winter climbing belay stances that you so frequently find up in the Highlands.

The bombproof, heavy and warm style of the Fitzroy was the trend when I bought my first synthetic jacket – it was built to last in the ‘ming’ that you’re so often blessed with in Scotland and it did the job extremely well. To be honest, synthetic insulation was the piece of equipment you purchased because you knew you had to, not because you wanted to – oh how things have changed with recent developments in synthetic fibres.

Synthetic insulation is made from polyester that has been spun into filaments that creates a pocket of air between each fibre. This pocket then warms up from your body temperature and thus, provides warmth. This is exactly the same way natural down can be used to keep you warm.

Down versus Synthetic

We’ve not yet quite mastered a like-for-like synthetic alternative to down – its formation is just too unique – and so there are still some downsides (sorry) to synthetic insulation in comparison to it. That being said, there are also some upsides to using synthetic insulation over down.


Down offers the better warmth-to-weight ratio over synthetic insulation materials. Put simply, the unique 3D structure of down creates what is called loft which traps air more effectively than any synthetic fill in production at the moment. We could reach a point soon where synthetic insulation will be able to match up though. PrimaLoft is a good example of a type of fill that is getting very near to hitting that same warmth-to-weight ratio.

PrimaLoft fibres

Wet weather performance

Down doesn’t have a natural ability to repel water (on a goose or duck it’s protected under larger, oily feathers), and so, if it gets wet it will clump together, lose its loft and in turn fail to trap warm air. Synthetic insulation on the other hand won’t collapse when it gets wet to the same extent as down, so in wet conditions you can still count on some insulation value. Bear in mind though, that these days it’s possible to treat down with a solution that gives it hydrophobic properties – so it’s hard to say outright that synthetics are better in wet weather than down! The debate rages on…


Plucking a helpless goose/duck of their lovely insulating down isn’t a very nice thing to do. Fortunately, many reputable outdoor brands these days (though not all of them) take measures to ensure that the down they use is responsibly sourced. This is an argument explored in our best down jackets test.

On the flip side, many are concerned about the impact of synthetic fibres on the environment – they’re normally made from plastic after all. To address this issue, brands like Polartec and PrimaLoft have managed to develop fills that can be recycled. There’s also a fully biodegradable and recycled fibre called PrimaLoft Bio which is now available in some jackets. With these developments in mind, the scale is perhaps tipping in favour of synthetics on this front.

Give our Down and Synthetic Insulated Jacket Buyer’s Guide a read to get a real in depth look into the designs and technologies behind both fill types.

Best Synthetic Insulated Jackets

OM Editor Will has taken a range of jackets out with him in Snowdonia and the Brecon Beacons. I took a bunch up to the Highlands and the Alps during some ski touring weekends. Many of the items featured here were actually good enough to be selected for our Green Gear Guide and Outdoor 100, meaning they past our gear team’s rigorous selection processes.

  • Keela Talus – Best in Test Synthetic Insulated Jacket
  • The North Face Thermoball 50/50
  • Cortazu Mid-Layer (All Season)
  • Arc’teryx Norvan SL
  • Montane Phoenix Stretch
  • Houdini Heavenly Houdi
  • Haglöfs L.I.M Mimic Hood
  • Finisterre Biosmock
  • Patagonia Nano Puff With PrimaLoft Gold Eco
  • Arc’teryx Nuclei FL
  • Outdoor Research Shadow Insulated Hoody
  • Cotopaxi Teca Calido


Jordan using the Black Diamond First Light Hoody during a 2700m hut tour.
The Mountain Equipment Rampart providing a shield to blizzard conditions.
OM Editor Will taking the Jottnar Elvar on his 100-mile walk across the Beacon Way.

BEST BUY: Keela Talus

Weight: 600g
Price: £140
Insulation: 60g PrimaLoft Gold Insulation

The Keela Talus is a great value jacket, one that’s perfect for anyone who tends to venture into cold and wet places. It features 60gsm of PrimaLoft Gold synthetic fill, bringing lightweight warmth and insulating performance even in wet conditions. What’s more, at least 50% of this fill is made from recycled content, more specifically, plastic bottles diverted from landfills. 

Then there’s the outer shell fabric which is both lightweight and durable thanks to the Cordura fibres that make up the ripstop thread within it. Stretchy fleece-lined panels then line the sides of the torso and under the arms to add a bit of extra comfort and to aid the overall temperature regulation as well. 

Features include an external zipped pocket on the chest, a zipped pocket on the inside and then two handwarmer pockets which are large enough to take an OS map. There’s also elasticated cuffs, an adjustment on the hem in the form of a glove-friendly cinch and an adjustable hood. Speaking of the hood, this has a malleable wired peak to keep the rain off your face and it’ll fit comfortable underneath a climbing helmet. 

Full Specifications

60gsm PrimaLoft Gold synthetic insulation / insulation made from 50% recycled content / summer and winter compatible / Cordura ripstop fibres in the outer / stretchy fleece-lined panels on torso sides and underarms / external zipped pocket on chest / zipped pocket on inside / two handwarmer pockets / elasticated cuffs / adjustable hood with malleable wired peak  

Selected for the 2021/22 Outdoor 100 – Read our full Keela Talus review.



The North Face Thermoball 50/50

Weight: 510g
Price: £315
Insulation: 100% recycled Thermoball polyester insulation

This is the first instance of The North Face’s 50/50 technology being used with a synthetic fill. All previous designs used down. The baffle design and fabrics, from what we can tell, are largely unchanged too. The baffles all hang off the inside of the jacket with large spaces between them and the materials are all light, slightly stretchy and they’re air permeable while still being densely woven enough to lock all the fill fibres in securely.

100% recycled nylon is used across the arms while the nylon used across the body is 89% recycled. Then there’s the Thermoball insulation which is made from 100% recycled polyester derived from post consumer content – stuff like plastic bottles and packaging.

Details on this jacket include stretchy cuffs that can be pulled over mountaineering gloves, a simple, non-adjustable hood that can be worn comfortably underneath a helmet, a zipped internal pocket on the chest, and there are two handwarmer pockets that contain toggles for the hem adjustment. The jacket can also be packed up into its left pocket.

Full Specifications

PFC-free durable water-repellent treatment / 100% recycled nylon across arms / 89% recycled nylon across body / 100% recycled Thermoball polyester insulation / baffle design / stretchy cuffs / non-adjustable hood / zipped internal chest pocket / two handwarmer pockets / packs into left pocket.

Selected for our Green Gear Guide 2023 – Read our full The North Face Thermoball 50/50 review.



Cortazu Mid-Layer (All Season)

Weight: 624g
Price: €149
Insulation: 60g

Another sustainable offering, this time from Netherlands-based newcomer Cortazu who first burst onto the market with a three-layer jacket made from fully recycled and recyclable materials.

This, the ‘Mid-Layer’ from Cortazu features lightweight insulation to provide a nifty balance between warmth and weight for when you’re working hard. Special props have to go out to that Airtastic outer fabric that offers a good level of stretch and a soft touch, giving it a great level of comfort when worn as either an standalone jacket for warmer climes, or part of a layering system during the cooler months.

This time Cortazu’s sustainability is focused on re-greening farming land for countries in need. For every jacket sold, Cortazu are promising to work with Justdiggit to re-green fifty square miles of what was once fertile farmland at the foot of Kilimanjaro – nothing to dislike about that.



Arc’teryx Norvan SL

Price: £350
Weight: 270g
Insulation: CoreloftCompact

If you’re after an insulated jacket made for high intensity activity in conditions that are as rough as they come, look no further than the Norvan SL from Arc’teryx.

The Norvan SL not only makes use of lightweight CoreLoft insulation, but there’s also a ridiculously lightweight and breathable Gore-Tex ShakeDry fabric for full waterproof protection. ShakeDry does away with the traditional face fabric you’d expect on a waterproof jacket, with the membrane instead exposed on the outside, the benefit being that the jacket will constantly bead moisture right off. It also means there’s no need to treat the outer with water repelling (DWR) chemicals.

Just be aware with the exposed membrane that the jacket is going to be at risk of fast wear, especially if you’re frequently rubbing against rocks, or wearing a backpack.

Full Specification

Gore-tex Shakedry eliminates the need for face fabric / slim fit optimises breathability / hood can be rolled and secured with snap when not in use / watertight front zip with chin guard / elasticised bottom hem for secure fit.



Montane Phoenix Stretch

Weight: 470g
Price: £125
Insulation: PrimaLoft Black ThermoPlume and PrimaLoft Silver

The Phoenix family of well-priced synthetic insulated jackets (Icarus for men) has been around for a few years now. We’ve seen a lightly insulated version, a heftier one, now we have this new one with super stretchy side panels and a nice new Pertex Quantum Eco face fabric. For just £125, you get “active insulation” with this jacket, providing breathable warmth.

This is how it works. There’s narrow baffles and a down-like synthetic fill for warmth, but then big stretchy panels under the arms that will let some hot air escape while also giving you a nice range of movement as well. With all that in mind, it’s going to be climbers who’ll get the most out of this jacket – it’s the kind of thing you could wear on the crag during those colder climbs from early spring through to autumn. But it’ll appeal to backpackers, hikers and bikepackers too.

There are excellent eco credentials. Montane have used a bunch of recycled fabrics in this jacket. You’ve got the outer Pertex Quantum Eco which is made from a 50% recycled polyester, the inner liner which is 100% recycled and then a PrimaLoft Silver synthetic fill on the shoulders and hood that’s made from 100% recycled materials as well. As for features, there’s everything you need: a water-resistant and windproof outer, internal storm flap underneath the main zip, deep hand-warmer pockets and a snug hood which is designed to fit comfortably under a climbing helmet.

Full Specification

Sizes: 8 – 16 women’s /  Pertex Quantum Eco 50% recycled outer with DWR / PrimaLoft Black ThermoPlume insulation in the core body and over arms / PrimaLoft Silver 100% recycled insulation in the hood and over shoulders / 100% recycled PEAQ Synthetic Eco lining / insulated under-helmet hood / full-length YKK front zipper with internal storm flap / two zippered hand pockets / pre-elasticated cuffs

Read our full Montane Phoenix Stretch review


Houdini Heavenly Houdi

Weight: 425g
Price: €280
Insulation: Primaloft Gold Active+

The Heavenly Houdi has been designed with cold weather activities in mind. It can be combined with other layers to create, as Houdini put it, the “perfect micro climate for ski touring, climbing or hiking”. If you wear a shell layer over the top of it, the fluffy padding is well suited to trapping air and keeping you warm and cosy on those coldest of ski slope days.

There’s a lot to say about the materials used in the Heavenly Houdi. The padding is PrimaLoft Gold Insulation Active+ which is highly water repellent, super durable and quick drying with an exceptional warmth-to-weight ratio. It’s made from 55% recycled polyester and 45% regular polyester. You also get a PFC-free DWR finish, a 100% recycled polyester Lite Breather lining and a C9 Ripstop outer fabric that’s ultralight yet durable.

The Heavenly Houdi has been put together with sustainability very much in mind. It’s been made from recycled parts and can, once you’re done with it, be recycled too. Weighing in at 425g, it’s lightweight and very packable. Stuff it in your backpack, when you’re out and about, and you’ve got a brilliant option when the temperature drops. The zippered side pockets that double up as vents are a nice feature, allowing you to get some cool air flowing when you’re really working up a sweat. The drawcord in the bottom hem is also great for adjustability and ensuring you keep the elements out, and the same goes for the high collar and head covering hood.

Full Specification

Sizes: S-XL / regular fit / padded with Primaloft Gold Active+ 60g in body, 40g in sleeves / PFC-free water repellency treatment / light and durable / highly packable / zippered side pockets that double as vents / high collar / drawcord in bottom hem / made with recycled and recyclable fibres

Read our full Houdini Heavenly Houdi review



OM testers Holly and Will with Haglofs LIM Mimic jackets on the Cumbria Way. Photos: Joe Whitmore

Haglöfs L.I.M Mimic Hood

Weight: 370g
Price: £210
Insulation: Mimic synthetic insulation

The fill Haglöfs have used here is called Mimic. It’s a mix of synthetic fibres that are designed to look like, feel like and perform like down, with the added benefit that they won’t lose their insulating properties when they get wet. These clusters are even blown into the jacket’s baffles following the same process used in down garment manufacture.

There’s more though, because these synthetic clusters also have a graphene filament mixed into them and the benefits of this are actually quite remarkable. Graphene, you see, is a material that’s mainly heralded for its remarkable low-weight, high-strength ratio, but it’s also a super conductor of heat too. That means it’ll take heat from high warmth areas, like your arm pits, and spread it throughout the jacket.

Details include deep handwarmer pockets, an elastic-rimmed hood that’s comfortable underneath a climbing helmet,  elasticated cuffs and that’s about it – not much in the way of details but, as they say, Less is More (LIM).

Full Specification

Climate neutral company / 100% recycled polyamide outer and inner fabrics / 100% recycled polyester fill / PFC-free water-repellent treatment / Mimic synthetic fill / deep pockets / elastic-rimmed helmet-compatible hood / elasticated cuffs.

Read our full Haglöfs L.I.M Mimic review


Finisterre Biosmock Insulated Jacket

Weight: 350g
Price: £225
Insulation: HD Wool Active Insulation

Cornwall-based brand Finisterre is an industry leader when it comes to eco-friendly apparel. And one of the most outstanding examples of their sustainable ethos in action is the new Biosmock – a puffy pullover that managed to nab a Gold Award in the Insulation Apparel Category at the 2021 ISPO event.

The Biosmock is a classic insulated smock with a four-button placket that has a fleece-like style but with the warmth and weatherproofing of an insulated jacket. Its outer shell is made from an innovative new fabric called PrimaLoft BIO, a PFC-free synthetic material that is biodegradable on land and in the sea.

Inside that fabric shell is a layer of insulation made from HD wool, a compound of natural sheep’s wool and PLA (polylactic acid, a plastic made from corn starch or sugar cane). It’s also fully biodegradable, while the wool itself is renewable, fully traceable, ethically produced and sourced from farmers who have signed up to eco schemes to improve biodiversity, soil health, natural irrigation systems and carbon sequestering.

Full Specification

ISPO gold winner / PrimaLoft BIO PFC-free fabrics / biodegradable /  HD Wool Active Insulation / no zippers / placket and kangaroo front pocket with press studs / water soluble, compostable and recyclable packaging.

Selected for the Green Gear Guide 2021/22 – Read our full Finisterre Biosmock review.



Patagonia Nano Puff With PrimaLoft

Weight: 337g
Price: £180
Insulation: 60gsm PrimaLoft Gold Insulation Eco 

The new-and-improved Nano Puff jacket now uses PrimaLoft’s innovative 100% post-consumer recycled polyester insulation made with P.U.R.E. (Produced Using Reduced Emissions) technology. It’s still the same high-performance 60gm PrimaLoft Gold Eco fill used in previous iterations, but with even less impact on the environment. Specifically, this innovative process reduces carbon emissions by a whopping 70% by altering the way the synthetic fibres are bonded together.

The Nano Puff also has a 20-denier 100% recycled polyester shell and lining, while the jacket is Fair Trade Certified sewn. And of course, it comes with all the traditional benefits of synthetic insulation – it offers decent warmth for weight, it’s hard-wearing and compressible, and boasts excellent moisture resistance.

The feature set is relatively simple but practical. It includes a full zip with a soft chin guard, two zipped hand pockets and an internal zipped chest pocket. There are elastic-bound cuffs and a hem drawcord. The hoody version also includes a snug elastic-bound hood. The fit is fairly accommodating, and if you hover between sizes, we’d tend to recommend going for the smaller size. But all in all, it’s a very comfortable jacket to wear.

Full Specification

Light and packable / 20-denier 100% recycled polyester shell and lining / 60gsm PrimaLoft Gold Insulation Eco made with 100% post-consumer recycled polyester / lower carbon footprint due to P.U.R.E. technologies / PFC-free DWR finish / bluesign approved.

Selected for the Green Gear Guide 2021/22 – Read our full Patagonia Nano Puff Primaloft P.U.R.E. review.



Arc’teryx Nuclei FL

Weight: 325g
Price: £250
Insulation: CoreLoft

Built for climbers and mountaineers, this is spot on as a belay jacket; it’s the thing that won’t weigh you down or take up much space in your bag when you’re moving fast and light, but then, when you’re paused and your heart rate is slowing, it’s the jacket you’ll want to pull on for that guaranteed warmth, even in wet and miserable conditions.

The fill used in the Arc’teryx Nuclei FL is the brand’s own CoreLoft insulation. In terms of the way it’s structured, CoreLoft is very comparable to Polartec Alpha, its fibres are tangled into pillow-like sheets in each chamber. These sheets all manage to suck in air, giving the jacket a very lofty feel. It doesn’t feel quite as lofty and down-like as PrimaLoft Gold does but then on the other hand, it feels thicker and more durable.

80g of CoreLoft insulation is used in the body and then there’s 60g in the side panels and sleeves, making for an overall warmth that packs a punch. At just 325g overall the Arc’teryx Nuclei FL is by no means a heavy jacket either. One of the main contributing factors here is the outer shell, which is made from a fully windproof 10D nylon with a ripstop weave. It feels very, very thin. Not so thin that you’d need to worry about the fabric on the shoulders when wearing a heavy-loaded pack, but you’d want to be careful picking through any thick brush in it.

Full Specification

Sizes: XS-XXL / windproof / great warmth-to-weight ratio / compressible and packable / durable / water-resistant / trim fit for athletic performance / articulated patterning for unrestricted mobility / gusseted underarms for mobility and comfort / helmet compatible and adjustable hood with soft brim / full front zip with wind flap / elastic cuffs / slight drop hem / two hand pockets with zippers  two internal dump pockets

Read our full Arc’teryx Nuclei FL review



Outdoor Research Shadow Insulated Hoody
Weight: 473g
Price: $219
Insulation: VerticalX Eco SR insulation

The Outdoor Research Shadow Hoody is a synthetic insulated puffer that is sustainably crafted with recycled and bio-based materials, but also comes in muted contemporary colours and looks pretty stylish. However, when you need technical performance, it’s also cosy and packable, offering excellent warmth for weight.

The headline material here is OR’s VerticalX Eco SR insulation. This combines Repreve recycled polyester fill with Sorona, a renewable plant-based fabric that is particularly hard-wearing. The result is a highly compressible fill that offers excellent warmth for weight, a soft down-like feel and good performance even when wet.

The jacket’s hood is insulated and adjustable for an easy fit. An elastic drawcord hem and elastic cuffs with thumb loops hold things in place as you reach, stretch, and move around, whether you’re on the mountain or off it. There’s also plenty of mechanical stretch in the fabric itself. Combined with a soft feel, it makes for an exceptionally comfortable, easy-wearing jacket.

Full Specification

VerticalX Eco SR insulation / bluesign approved 20D nylon and elastane blend for outer fabrics and linings / insulated and adjustable hood / elastic drawcord hem / elastic cuffs with thumb loops  / two zipped handwarmer pockets / interior stash pocket.

Selected for our Green Gear Guide 2023 – Read our full Outdoor Research Shadow Insulated Hoody review.



Cotopaxi Teca Cálido

Weight: £120
Price: 350g
Insulation: 60gsm 100% recycled polyester  

The Teca Cálido jacket has been built with sustainability in mind, with a shell that’s made from a repurposed polyester taffeta and a fill that’s 100% recycled polyester.  

This insulating performance is helped by a snug, elastic-bound hood, hem and cuffs plus two cosy handwarmer pockets and it’s packable enough to stuff inside its own chest pocket. 

This thing’s reversible too. On one side you get that funky colour-blocked design with two zipped handwarmer pockets and then on the other you get more muted navy styling, with square stitch-through baffles, a zipped chest pocket and two drop-in lower patch pockets. 

Full Specifications

Colour-blocked design / face fabric panels and shell made from repurposed taffeta with DWR finish and PU backer / 60gsm 100% recycled polyester stuffing / elastic-bound hood, hem and cuffs / two handwarmer pockets / stuffs inside its own zipped chest pocket / certified B-corp / 1% of brand revenue goes towards charitable initiatives / reversible / square stitch-through baffles / two drop-in lower patch pockets.

Selected for the 2021/22 Outdoor 100 – Read our full Cotopaxi Teca Cálido review.




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