Rab Mythic Ultra Jacket Review


Our Rab Mythic Ultra Jacket Review explores a state of the art down winter warmer by industry leaders Rab.  Please do read on to find out more about this special garment.

Rab Equipment

Nowadays Rab Equipment need little introduction, but it always feels special to review one of their down products because that’s where it all started.  The company was founded by Sheffield climber Rab Carrington who started sewing up down sleeping bags in his spare room.  His focus was on top quality and high performance and soon his products were being used on ground breaking ascents around the world.  

In the intervening decades the company has grown massively and they now produce a wide range of products.  From running to climbing to hillwalking, their range includes clothes, packs, tents and various accessories.  But down is still very much at the heart of their expertise.  So, when they asked me to complete a Rab Mythic Ultra Jacket Review I was delighted to dive in.  Please do read on to find out more. 


Down clothing and sleeping bags have been used by mountaineers throughout the history of the sport.  It therefore might seem like down clothing can’t evolve much further.  After all, it is feathers wedged between two layers of fabric.  The reality is that there is much still to change. Rab remain key to that industry development and their Mythic Ultra products are at the heart of recent innovations.




The Mythic Ultra has uses a 10 denier Pertex Quantum nylon ripstop outer fabric.  This is a 100% recycled material and it has a PFC free DWR (Durable Water Repellent) coating.  Pertex Quantum is designed to be a soft and windproof fabric that allows insulation to loft efficiently. Key to down products, it is also designed to stop down leaking out through the material. At 28 grams per square metre, it is also exceptionally light.


The insulation is 900 fill power European goose down.  There is 240 grams (8.5 oz) of down in the size medium.  The down meets the Responsible Down Standard.  This is an independent process which certifies down against animal welfare requirements and tracks it from the source to the final product.  The down is treated with a PFC free Nikwax hydrophobic treatment.   


The down is held in place by a combination of offset box wall baffles and stitch through construction.  Box wall baffles ensure no cold spots and maximise the expansion of the down in each chamber.  The Mythic uses these on the main body of the jacket where maximum insulation is needed. Stitch through construction is used on the arms and hood where more of a range of movement is needed.  Stitch through also minimises weight.  

TILT Technology

The Mythic Ultra also incorporates TILT technology.  Rab explain this as a ‘radical, heat retaining tech that works like an emergency blanket reflecting heat back towards your body’. TILT stands for Thermo Ionic Lining Technology. Luckily, in use, it feels nothing like wearing an emergency foil blanket!  

For the TILT layer, Rab use an aluminium treatment in a scrim liner.  This liner covers the torso of the jacket and reflects heat back to the body.  Rab experimented with various combinations of material and position to get the most efficient system.  They report that the system they adopted reduces radiant heat loss better than the 6 other key methods tested. 

The scrim layer covers the torso and sits as close to the body as possible.  Again, their research found that placing the TILT scrim on the inner layer resulted in 200% greater heat retention than having the liner on the outer side of the baffles.  In fact, to put a number of it, it was 44% better than the next best construction method.    

Other Features

The Mythic Ultra has a helmet compatible down filled hood with rear elasticated adjustment, concealed internal drawcord and stiffened peak.  The arms are pre-curved and there are articulated sleeves for freedom of movement.  There are two YKK zipped hand pockets and a chest pocket, dual sided hem adjustment with anti-snag tether.  The cuffs are part elasticated for optimum fit with minimal bulk.  Finally, the front closure is a YKK Vision 2 way zip with fleece lined chin guard.

The Mythic Ultra is available in a unisex design and comes in an orange colour called Marmalade (tested), a grey/black colour called Graphene and a blue called Orion Blue.  The size medium weighs 537grams and the retail price is £380.  The jacket is supplied with a lightweight stuff sack.

Hood Design

In Use

Rab market the Mythic Ultra for ‘fast moving Alpinists’ and you can see the focus on that user group in many design features.  However, it is actually well suited to lots of situations and activities.  You will love it if Alpinism is your thing, but then you are likely to put it to use cold weather belaying, winter camping or wandering to the pub on a cold night (it looks stylish enough for that use too!). 

But, the focus of our Rab Mythic Ultra Jacket Review is as a jacket for cold weather vertical adventures.  It has served time in a very wintry Snowdonia, on an extended Norway ice climbing trip and cold weather Peak District cragging.  How does it perform?


The Mythic Ultra tested was in the bright and cheerful Marmalade colour.  I think Rab have got the styling of this spot on.  The jacket looks suitably technical and ready for action, but generally just looks great.  The contrasting patch of the zipped chest pocket also really works a treat.  On first inspection you will also notice the baffle lines and details like the logo on the chest and high neck zipper.  It is all really stylish.  


I was sent a size medium and this fits my 38” chest perfectly.  Rab describe the fit as regular and I agree with that. The loft of the insulation means the jacket wraps around your body snugly, but there is still room for layers underneath.  In terms of length, on my 5’8” height the jacket sits low enough to protect below my waist without being too long.  It is actually a great fit that I would describe as true to size.

The other noticeable fit consideration is freedom of movement.  For a jacket designed for mountain use this is very important.  The Mythic allows very free movement.  I think this comes down to a good cut overall, but is certainly helped by the pre-curved and articulated sleeves and well designed hood. Finally, although hard to say how much of a factor it is, presumably the choice to use stitch through construction in key areas also plays a big part. 

Chest Pocket


The other thing you will immediately notice on first inspection and try on is the bulk of this top. Rab wanted to get a balance between a jacket that is light and compact enough to carry and use for active sports with being streamlined and well fitting enough for Alpinism.

I think they have nailed it.  Infact, Rab say this jacket offers the highest warmth to weight ratio in their entire range.  I can’t say whether this is true or not, but know Rab to not make unsubstantiated claims and so have no reason to disagree. The jacket lofts from storage beautifully and has a great cut for high insulation alongside freedom of movement.  The box wall ensures it offers the best level of warmth for the insulation material inside and this certainly works on this garment.

As a user it is also tricky to know how much difference the TILT layer makes to overall warmth. But, I am happy to take from the Rab team that it offers significant warmth benefits. The principle of user silver layers to reflect back heat has been used in many contexts for many years. It makes sense that it will add benefit here.

In use you really won’t notice the TILT layer either. It don’t make any crinkly sound like a foil blanket and you can’t even see it. Users should just be reassured that it is there and doing its thing.

Fill Power

The level of insulation the Mythic Ultra offers is down to the design and cut of the shell, the outer and lining material and the insulation material used.  In this case Rab have used 900 fill power down.  Fill power is a measure of the quality (rather than quantity) of the down. It is a rating system that represents the volume in cubic centimetres of a single gram of down when fully lofted. The higher the fill power, the warmer a garment will be for its weight.  Put simply, 900 fill power is exceptional quality.  There is lots of useful information about fill power on the companies Rab Lab here. 

How this translates to the user is seen in the loft of the Mythic Ultra.  The jacket is a bundle of warmth.  Even if it has been stored in a stuff sack you will see it lofting efficiently as soon as the jacket is pulled out.  Give it a few shakes and it is ready for use.  It is very impressive.

Shell & Liner Fabric

Having said all that about fill power, the other key influence in how well a garment lofts is down to the fabrics used. A fabric has to let air through to allow the down to loft.  But, a fabric also has to work against other criteria. It needs to offer some level of moisture resistance and yet allow enough air flow to allow moisture coming from the body to escape.  It needs to keep the down from escaping through the fabric. The fabric also needs to be durable enough to survive the rigours of use. Pertex Quantum has been a favourite for technical garments for many years as it meets these criteria so well.

I am always careful when using garments made with fabrics this thin. By their nature, they won’t be as durable as thicker materials. They also won’t be particularly water resistant. But, if you take care you should find Pertex Quantum to do its job extremely well. On a recent trip to Norway it fended off some snow and stood up to being pushed in and out of a stuff sack several times a day. But, I was always sure to keep it away from spiky picks and ice screws – it would never win that battle. Like always, it has to be a trade off.

Packsize & Stuffsack (Included)

Nikwax Hydrophobic Treatment

As good as down is, its ability to insulate is significantly compromised by moisture.  One way to help overcome this is to treat the down with a hydrophobic treatment. This is especially important when using less water resistant outer fabrics, but even if you do moisture is constantly also being created by the body.

So, down proofing serves benefits both ways.  Rab exclusively use Nikwax down proofers.  This is a brilliant development.  Although the treatment won’t make the down waterproof,  it certainly makes it far more water resistant.

Hood Design

While not seeming like a big thing, I think hood design (good or bad) can be a key indicator of how well a product has been thought out.  Getting it right is also key to the performance of an insulating jacket.  The Mythic Ultra hood is superb.  It is sold as being helmet compatible and it really is.  I have tested it with a Petzl Sirocco and, even with it cranked tight, it offers excellent freedom of movement.

Good field of vision is also helped by the stiffened peak.  If you aren’t wearing a hood the volume is likely to need adjusting.  This is easy via the elasticated rear adjuster.  Finally, to pull it snug around the face the concealed inner drawcord does the business.  I don’t think Rab could have designed this better. 

Other Features

As a jacket focussed on mountaineering and Alpinism, it is great that there are several features designed in for that purpose.  The main zipper is a top quality YKK 2 way.  Having a two way opening is important when using the jacket for belay duties. It also aids ventilation when needed.   The zipper also has a fleece chin guard which makes it very comfortable to have the zip pulled up fully.

There are 2 YKK zipped hand warmer pockets.  They are perfect for warming hands or carrying essentials.  They are also placed to avoid interfering with a harness.  An additional chest pocket is really useful for storing a phone or smaller essential items. 

On the Marmalade colour tested this pocket is in a contrasting black colour.  The striking design of this divided opinion when friends saw the jacket, but I really like it.  

Sleeve Cuff Design


Finally, for this Rab Mythic Ultra Jacket review it is important to consider sustainability.  Consumers nowadays are much more aware of the environmental impact of their choices.  Fortunately, if you buy a Rab product you are buying an item where this is considered at every stage of design and manufacture.

Rab are industry leaders in sustainability. They have been climate neutral for several years and each year the percentage of recycled fabrics in their product line grows.  The last stat I got was 63%, but even by the time this review is live that might be higher.  They also drive the industry with various sustainability initiatives and strive to make all their products repairable through the Rab service centre.   

The Mythic features 100% recycled Pertex on the inside and outside and the down meets the Responsible Down Standard.  If you aren’t familiar with the requirements of this standard please have a read here.  The DWR coating is PFC free and the Nikwax hydrophobic down treatment is a PFC free water based treatment.  Again, it is worth having a read about Nikwax products and their strong drive to sustainability on their website here.

Handwarmer Pockets


My Rab Mythic Ultra Jacket review hopefully makes my thoughts on this product clear.  It is a peach. The Mythic Ultra looks great, fits perfectly and performs superbly.  It is ideal for the stated use of Alpinism and mountaineering, but actually a much broader range of users would find this to be a great choice.  It is also made with sustainability at it’s heart.  

Rab keep producing winning products and here’s another.  Literally!  The Mythic Ultra has won a clutch of industry awards and they are well deserved.  Please do check out full details on this jacket on the Rab website here. There is also a Rab Lab video explaining the key features of the jacket. Please have a watch below.

We have been proud to work with Rab for many years and this Rab Mythic Ultra Jacket Review is only one of several reviews we have done over the years. There are lots available on our blog. Please, for example, have a look at our review of their Ascendor 28l Pack here. We also reviewed their Kinetic Alpine 2.0 Jacket here. Finally, our recent review of their Mythic 600 Sleeping Bag is here.