Best Synthetic Insulated Jackets 2019 | Top 9 - Outdoors Magic

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Down and Insulated Jackets

Best Synthetic Insulated Jackets 2019 | Top 9

Synthetic insulated jackets offer reliable warmth in wet weather, compressibility and a long-lifespan. Here are the best options out there in 2019

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’y 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 due out soon. 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

We’ve had a turbo warm February of 2019, which has stripped much of the crags of their ice and snow. This has made for interesting testing for the heavier-weight jackets in this roundup, but also perfect testing for the more ‘active’ insulation pieces. 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.

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.

The jackets in this section of our roundup of the best synthetic jackets are all designed to be thrown on over your outer layers during periods of inactivity. They’re ideally suited towards cold weather climbing where you’re likely to reach a belay ledge and need that extra layer of protection whilst you’re not moving and creating your own warmth.

They’re options that would be suitable to walk all day in when the conditions are extremely cold, and they’d also be great to have in your pack to pull out on the summit or during a lunch stop. These jackets also come with a slightly ‘boxier’ or roomier fit to accommodate multiple layers of clothing.

Montane Flux

Weight: 624g
Price: £160
Insulation: 100g PrimaLoft Silver Eco

With a cut designed to be worn over the top of your winter layering system and a no-thrills what-you-see-is-what-you-get approach, British based Montane have shown their heritage with the new Flux which follows the classic Scottish winter belay jacket design.

100g of Primaloft Silver fills the chest and 60g fills the arms and hood. This variation in volume gives you a little more freedom to be able to move, which is further assisted by the loose internal cut of the jacket. It’ll be helpful when you’re sitting there on your belay perch, already caked in layers of wool, PrimaLoft and GoreTex and need to throw something over you quickly for extra warmth.

There are no gimmicks here. The jacket just works, and keeps on working throughout the day. I always appreciate a set of fleece-lined pockets, and the napoleon chest pocket is able to swallow up maps easily. This pocket will prove particularly useful when you need to quickly stuff away gear whilst hanging on by your crampons and a single axe.

Full Specification

Sizes: S – XXL / eco friendly fabric / water resistant eco fill / helmet compatible hood / two-way front zipper / two hand warmer pockets / two chest pockets / stuffs into right hand pocket.

Patagonia Micro Puff Storm

Weight: 530g
Price: £430
Insulation: 65g PlumaFill

Patagonia‘s PlumaFill, like PrimaLoft, is designed to replicate the structure of down. It claims to offer the warmth, packability and actual feel of natural insulation, whilst still holding all the wet weather performance of synthetic insulation.

Yeah, you’ve heard all of this before, I know. But PlumaFill, which has been used in various iterations of Patagonia’s synthetic insulated jackets, has had plenty acclaim over the years and we here at OM can vouch for it.

Just like the much-loved Micro Puff jacket, Patagonia has stuffed 65g of PlumaFill insulation into the Micro Puff Storm. But this is just about where the similarities end. That’s because what we have here is a waterproof and insulator combined.

Here, Patagonia’s PlumaFill insulation is housed within their own-brand H2No waterproof fabric. And they’ve combined this with waterproof zips and a huge helmet compatible hood that will happily swallow a climbing helmet for when the spindrift starts piling down on you.

With the recent super-warm February, we’ve sadly never found an occasion to really put this jacket through its paces. The only time was in an attempt to hide out from some relentless Cairngorm winds over on the plateau. Still, this jacket had a real ‘barrier’ feel to it, blocking out all of the nasty weather.

Full Specification

Sizes: XS – XXL / 2-layer H2No waterproof fabric / PlumaFill insulation / seamless shoulder design reduces possible abrasion points / helmet-compatible hood / elasticised internal snow skirt.

Salewa Ortles TriolWool Celliant

Weight: 557g
Price: £225
Insulation: Triol Wool Celliant 100/80g

Salewa have taken a step away from the more common technique of stuffing a synthetic jacket full of plastic fibres. Instead, the Ortles TirolWool Celliant jacket utilises wool from Tirolean Mountain Sheep combined with ‘Celliant’ synthetic insulation that has ‘performance enhancing properties’. The wool to synthetic mix is 40% wool to 60% synthetic.

Salewa say that this Celliant synthetic technology “is a patented mix of thermo-reactive minerals using a secret formula that’s closely guarded by its manufacturer”. It’s supposedly able to recycle radiant body energy (heat) into infrared light to “store and reflect it back” to the body over time – the jury really is out on this one as to how much this thermo-reactive formula actually makes a difference out on the hill. I didn’t really notice a stark difference in warmth when switching out this jacket with full synthetic equivalents over a long period of time spent on the Cairngorm plateau.

On top of the fancy insulating materials, Salewa have designed the cut of the jacket carefully for climbers to make sure it doesn’t lift up at the hem when reaching high. There’s also specific zoning of the insulation volume in the chest and shoulders to further assist with freedom of movement. The jacket is fairly athletic fitting, so you may wish to size up if you plan on using this as a belay jacket over your shell layers.

Full Specification

Sizes: XS – L / wind-resistant / water-repellent / nylon ripstop shell / Powertex Extreme reinforced shoulders / TirolWool Celliant insulation material / insulated, fitted hood.

Haglöfs Essens Mimic Hood

Weight: 485g
Price: £180
Insulation: QuadFusion Mimic

Haglöfs seem to have stolen the blueprints for the mid weight stitch-through down jacket here. It’s got an almost identical look and construction, but rather than using natural fill, they’ve stuffed it with their own synthetic QuadFusion Mimic, a 100% recycled fibre that has the light, fluffy and lofty feel of down.

During testing, I found it extremely mobile, particularly when used as a warm midlayer, with the fairly short cut slotting underneath a waterproof with ease. The jacket moved with me well when ski touring and also walking up some steep snow slopes, all thanks, in the most part, to the stretch panels in the armpits. These also add extra breathability in what usually becomes a fairly warm area. Throw in the quality Pertex outer fabric, helmet compatible hood and chest pocket and you’ve got a very useful midlayer for alpine adventures.

Full Specification

Size: XS – XXXL / 30D  wind resistant Pertex fabric / short cut / stretch fleece shoulder inserts / 3-way adjustable hood / two zippered hand warmer pockets / one chest pocket / regular fit.

Hybrid Jackets and Active Insulation

These ‘hybrid’ or lighter weight synthetic insulated jackets are designed to be used as midlayers, particularly for winter walking, ski touring and winter climbing, where they can be left on while underneath a shell or wind stopper to provide warmth throughout the day.

Due to their lightweight and breathable nature, they should let sweat out much better than their more heavyweight counterparts listed above. Generally the fill weight is lower, and/or will be body mapped, and thinner fabrics will feature in certain places or indeed throughout.

Black Diamond First Light Hybrid Hoody

Weight: 520g
Price: £200
Insulation: PrimaLoft Silver Active – 60g/m2

The Black Diamond First Light is a great option out in this list of the best synthetic insulated jackets if you’re looking for something that’s going to work purely as a mid layer, particularly during high tempo scenarios.

It features a clever zoning of materials to provide insulation and ventilation in all the right places, with 60g/m2 of PrimaLoft insulation on the chest and then a merino wool blend covering the underarms and back – exactly where your body is going to be looking to shift sweat and heat when you’re moving fast. I found this midlayer offered minimal restriction in movement whilst ski touring and winter walking, giving me pretty decent insulation to hold up to a typical winter’s day spent on the Cairngorm plateau.

The insulated sections of the First Light Hoody have been wrapped up in premium Schoeller fabric. This material gives the jacket an extra kick in all-weather performance, as I discovered when caught out in a fairly light rain shower up in the Highlands. All that was required was a quick brush of the jacket and all of the water beads would dissipate – look after this jacket and it’ll keep up this performance.

Full Specification

Size: S – XL / under-the-helmet hood / PrimaLoft Silver Active / underarm gussets for added range of motion / two zippered hand pockets / concealed zip chest pocket / slim fit.

Jöttnar Elvar Thermolite

Weight: 420g
Price: £249
Insulation: Thermolite 100g/m2

You get the usual clean and streamlined design that you come to expect from Jöttnar with their new Elvar Thermolite insulated jacket. Even though it’s packed with a slightly heavier 100g/m2 of Thermolite synthetic insulation, this is one that can be worn as a very warm midlayer when the forecast drops into the negatives, due to the breathable stretch nylon outer fabric.

And it could still prove useful when things warm up during the spring and summer seasons as well, making for a good fit as a stand-alone belay jacket, or for keeping the wind off you on lofty summits.

OM Will Renwick can vouch for its qualities. On his mid February hike along the Beacons Way, he says he barely took it off and often wore it under a fairly thick waterproof shell without any discomfort.

Full Specification

Size: S – XL / Thermolite insulation / stretch nylon windshell outer / four outer pockets provide hand warmth and storage for essentials / under-helmet hood.

Rab Xenon X

Weight: 343g
Price: £170
Insulation: PrimaLoft Gold 60g/m2

Utilising PrimaLoft’s top tier Gold Active insulation, the Rab Xenon X makes for a bridge between the heavyweight and mid weight insulated jackets in this roundup. You’ll be surprised at just how warm this jacket actually is, given it’s weight. It makes for a great super-lightweight Scottish winter belay jacket, particularly if you’re not too keen to bring along one of the extra approximately 200g heavier jackets in this roundup.

The insulation within this jacket is active however, and this means that it will breathe, letting out a bit of warmth and with that, sweat. All-in-all this jacket is a real versatile piece. You’ll find a bit more about it in our editor’s Cambrian Way Kit List report.

Full Specification

Size: S – XXL / Pertex Quantum outer / PrimaLoft Gold Active / under helmet hood / 2-way opening YKK zip / internal insulated baffle / 2 zipped hand-warmer pockets / 1 zipped pocket, doubles as integrated stuff sack / slim fit.

Mountain Equipment Rampart

Weight: 395g
Price: £120
Insulation: PolarLoft Micro 80g/m2

Mountain Equipment have designed the Rampart to be layered beneath your outer layer in those horrific weather days where it feels like you can never have too many layers on. Although it has been designed as a winter midlayer, this doesn’t mean that you can’t use it as an outer or summer belay jacket, with the Helium 30 outer fabric offering pretty decent windproof properties.

I used the jacket whilst out ski touring up in Scotland and loved the clean cut and feel of it. It moved really well with me, fitted perfectly under a shell and also performed as a great standalone jacket whilst ascending, with just a baselayer beneath. Once on the summits, you really do want to throw a hardshell over the top of this, no matter how windproof Mountain Equipment claim their Helium 30 fabric is.

I can also see this becoming my go-to jacket for mountain cragging or belaying during summer single pitch evenings.

I hate to say it, but this jacket also makes for something you can wear around town without onlookers thinking you’ve just stepped right out of Everest basecamp. It’s got a fairly unique stitch through pattern to hold the insulation in place, which makes for a smart look.

Full Specification

Size: S – XXL / Helium 30 outer / PolarLoft Micro insulation / mountain hood / 2 zipped hand warmer pockets / inner pocket / packs into hand pocket with twin karabiner carry loops.

Forclaz 100

Weight: 335g
Price: £29.99
Insulation: Recycled polyester 100/80gm/2

The jackets in this roundup are averaging around £200 – £250 per jacket and the Micro Puff Storm reaches the lofty heights of £430. This made us keen to include a more budget option. After all, there are many out there who’ll be just getting a feel for winter walking, ski touring or climbing, and it can seem pretty daunting when you see all the fancy technologies and premium price tags that accompany them.

Whilst the Forclaz 100 doesn’t hold half the feature set of many of the other options in this round up of the best synthetic insulated jackets, it does still pack a fair amount of insulation (100g/m2 in the body and 80g/m2 on the hood and arms) for a decent weight (335g). You definitely can’t turn your nose up at these stats given the tiny price tag of £29.99.

Full Specification

Size: S – XXXL / stuffed with recycled wadding / water repellent fabric / easy to roll up and store.


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