Yukon Down Jacket: K Series

'K Series' version of our box-wall, lightweight mountain down jacket. Warmth to weight at the limit of possibilities via design innovation and unique materials. Now also available in custom sizes.
Typical Operating Temperature
Guideline minimum temperature. Sleeping Bag TOT: you should get a night’s sleep, under normal circumstances. Clothing TOT: you should feel warm enough, assuming low/moderate activity. Sleep System TOT: relates to full system. For more details, see our Technical Briefing.
-15°C / 5°F
For clothing, weight is for size: M. For sleeping bags, weight changes with selected length/width. N.B. there may be some variation in the weights of finished products.
380g / 13oz
Yukon Down Jacket: K Series

I can't praise it enough for overall performance. This is the warmest jacket for its weight that I've ever tested.
Lucy Wallace in TGO Magazine (Jacket was "Best" & "Lightest" in test)



  • A PHD K Series product: Ultimate warmth / weight performance
  • PHD's Unique 1000 fillpower down
  • Water-resistant Ultrashell outer. An excellent balance of weight, water-resistance and breathability
  • Superlight 10X inner fabric. Down-proof, wind proof and super soft
  • Box-wall construction for maximum loft
  • Lightweight front zip with internal draft baffle
  • 3 zipped, insulated pockets:
    • 2 waist level handwarmer pockets
    • 1 Insulated chest pocket
  • Reflect zip pullers 
  • Double-exit shock cord hem
  • Drop-tail back
  • Stuff sac
  • Stud-on superlight down hood with stretch Lycra edging
  • Pack size: 13 x 21cm*

*Please note: We make our stuff sacs big enough to allow fairly easy stuffing rather than reducing the jacket to the tightest minimum.


This K Series product has been created for one single reason, to take warmth-for-weight performance to the limit of what's possible. Unique 1000 down, super-light materials, and specific design features mean that the word Ultralight now applies to this wide range of gear that will take you to the Poles as well as on a Sahara Marathon. More on the K Series...

Also available in custom sizes. We make clothing to order, so if you’re not a standard size we can make it to fit. To order a non-standard custom size, select the Custom Sizing tab, choose your body width, and then the body/arm lengths, shorter or longer, that work for you. A custom size takes us a little longer (typically two weeks longer) to make and, because it’s personalized, it’s non-returnable and our customer loyalty scheme can’t be applied.

Still the same warmth, still the same box-wall construction protected by a windproof water-shedding outer, just as it was in the original Yukon race jacket used in temperatures down to -30°C.* But at 380gm this K Series Yukon is 15% lighter and will pack down that much smaller.

Our lightest and finest materials, 1000 down, 10X inner fabric and windproof water-resistant Ultrashell outer, along with lightweight (No.3) zips have taken this wonderful jacket to a new level of lightweight performance.

The remarkable weight and pack-down size of the Yukon make it ideal for lightweight mountaineering, high level trekking, cold races and long distance hiking.

Weighing just 380gm (13.4oz) complete with hood, it combines a water-resistant Ultrashell fabric outer with a super lightweight 10X fabric inner. Its box wall construction and unique 1000 fillpower down boost its performance well beyond the rest of our ultralight clothing. 

The handwarmer pockets are zipped to keep out blowing snow and there is a stretch drawcord in the hem. The insulated chest pocket keeps a GPS (or other battery-operated kit) both warm and easily available. The reflect zip pulls are a safety feature, improving night-time location. 

This is not designed as a high mountain jacket like the Hispar or the Xero. But when the kit has to be ultralight and stitch-through jackets are just not warm enough, the Yukon can be the ideal choice.

*Note Temperature rating. Race competitors balance comfort against weight by a different scale to most other people. The Typical Operating Temperature (TOT) of -15°C is the NORMAL rating for this jacket, while -30°C is the racers' rating.


Ultrashell (weight: 40 gsm)

One of the lightest of PHD's coated materials. This ripstop nylon provides complete wind block and good water resistance at minimal weight. Ultrashell gives an excellent upgrade to performance with very little weight penalty.

Ultralight 10X fabric (weight: 26 gsm)

10X, PHD's first 10 Denier Fabric. 9,000 metres of the yarn used to weave 10X weighs just 10g, that's about the same as a £1 coin! For all its thinness 10X is amazingly downproof and with reasonable care will go on giving you good service for years.

1000 fillpower down

This rarest of all downs we reserve for the K Series. European goose down of unique quality. 1000 provides the highest warmth-for-weight performance possible from down. More on our down insulation.

"Uses the lightest materials to ensure maximum performance for minimum weight. Filled with 1000 fill power down, which has unbeatable lofting capabilities. Cosy, with ultra-lightweight zips. The hood can be removed if weight is critical. I can't praise it enough for overall performance. This is the warmest jacket for its weight that I've ever tested. Idea for treks at altitude, multi-day mountaineering in cool conditions, and other cold undertakings where weight is critical."
Lucy Wallace in TGO Magazine (Jacket was "Best" & "Lightest" in test)

"The Yukon jacket - K series - was fantastic. You warmed up as soon as you put it on and you barely noticed you had a jacket on, it was that light-weight! It stashed to virtually nothing in the small stash bag, which meant that I could easily put it in my day rucksack with water, cameras, other clothing without it taking up too much space. As soon as we got in to camp, the jackets went straight on to make sure we did not get too cold standing around. The whole package was excellent - good, roomy pockets, easy to use zip and a very warm hood. It was a real saviour."
Graham Brothwood, 9 day camping trip to Langtang Valley (Nepal) up to 3,840 metres.

"The Yukon is very light and the down fill is the softest I've ever felt, I haven't found one single shaft or barb inside the baffles of the jacket. The Yukon's hood … sits there perfectly and doesn't slip back or forward when I'm moving. It's so light and soft it might feel fragile in your hands but this a proper winter mountain jacket all the way."
Peter Macfarlane (PTC) review in WalkHighlands.

"I am sure that you will be interested to hear that our blue Yukon jackets fitted perfectly and kept us warm and snug in the Arctic snow. The jackets were the envy of everyone on board - praise indeed from such experienced travellers."
Nigel Humphries.

The comments below relate to standard Yukon Down Jacket, which is 95g heavier

"Many thanks for the jacket that you supplied me for the Yukon Arctic Ultra. [It] performed perfectly in temperatures down to -35c. The light weight and small size was also a huge help and helped me gain second place in the race. I ... am now the second fastest person over the course and the fastest European."
Dr Stuart Gillet (wearing a prototype Yukon jacket).

"Without PHD kit I would have been toast."
Jacob Hastrup 2nd place in Yukon Arctic Ultra 100 mile race.

"I'm always proud when I tell mountain guides and our guests about PHD and about the origin of my down clothing. The Yukon Down Pullover was been my best buy ever. In avalanche training courses it was possible to wear the pullover the whole day at -20 degrees Celsius!"
André Henzen, UIAGM Mountain Guide, Switzerland

"I used a Yukon down jacket with Gore-tex outer on the expedition. It packs down small (half the size of my previous jacket), it's great for early starts and when the snow starts falling."
Dominic Southgate - Imperial College Reru Valley Expedition (Zanskar Himalaya, India).

"For more serious winter outings I use PHD's Yukon Down Jackets. PHD make the best lightweight kit on the market. I just wouldn't go Munro bagging in winter without mine. It's fab."
Phil Newby.

"Ben was impressed with the Yukon Jacket I bought for him. In fact, we ended up fighting over it on more than one occasion! Again, simplicity of design, total warmth, amazing lightness and quality of manufacture was what made it stand out from the rest."
James Garrett.

"Thank you for the Yukon jacket! It fits super, is warm and nicely made."
Mark van Onna.

"Just wanted to thank you for the prompt delivery of my Yukon down jacket. It is fantastic and I have worn it constantly since it arrived."
Lise Cooper.

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