Arc UL Three Season

New product

Ordering closed until mid August. See top banner

The Arc UL quilts are designed for optimal efficiency in the environments met by long distance hikers.

Custom features including sizing and weight saving options.

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Pay via Credit Card or Paypal Account

Ordering closed until mid August. See top banner

  1. We measure the actual width of the finished quilt without stretching. 
  2. This measurement is a minimum. 
  3. The differential cut makes the inside narrower than the outside. The stated width is based on the inner.
  4. Adequate quilt width is the number one defense against cold inducing drafts. Our recommendations will get you a quilt generally wider than other brands with similar specs.


Appropriate use

This trio of quilts is designed to provide sleeping comfort in the western US mountains from April to October.

The 30° Arc UL is warm enough to serve as a general purpose quilt for an experienced backpacker.

The 20° rated Arc UL is the standard go-to, do anything quilt. Our most popular choice for long-distance hikers ready to keep going into fall.

The 25°F rated in-betweener is the sweet spot for the undecided folks not knowing if a changing climate really warrants a 20°F quilt anymore

Fill and Loft

In the menu you'll find three temperature ratings, realistically defined as either 30°F, 25°F or 20°F. The loft is a between 1.90” and 2.60”.  Fill volumes for either level are detailed in the charts, and offer further insight into whether these quilts will meet your needs.


The length is in 4" increments defined by measurements plus X-Small to X-Long descriptors. Using this system you can choose how far up the quilt reaches when on your back. In open mode reaching just the chin level is the absolute shortest anyone should go, and then only on quilts for the warmer seasons. Reaching the user's forehead is the best compromise of low weight - efficient coverage. As always, it is prudent to size up if in doubt. If just a little too short one tends to compress the foot area insulation to the detriment of cold toes.

The shoulder and foot area widths can be customized for individual needs and sizing. Newcomers to backcountry quilts can experiment with a blanket before committing to a sizing setup. 

Foot End Design

The Arc UL is built with a permanently closed foot section of about 16" to 20” length and then finished with a round bottom piece. A design common with high-end mummy bags.

Shell Material Choices

Immediate apologies for the complexity of the following! 

We offer the discerning user options to fine tune the performance of the Arc UL via a series of technical shell materials.

Ultralight: 10d ultralight breathable shell. 

This ultralight fabric creates a comfortable sleep environment at the lowest weight. It will, however, wet out and transfer moisture to the down if exposed to prolonged dew, mist and damp tents. On the other hand, the superior breathability allows it to dry quickly in the sun. Ideal for moderately dry weather, desert hikes; or anywhere with a traditional double walled tent.

Classic: 15d lightweight breathable shell.

Nearly the same properties as the ultralight material above, but a significant increase in durability and tear strength. Expect a weight increase of up to 2 ounces, depending on size.

Full Moisture protection: 7d ultralight waterproof/breathable shell.  

With this as your outer material there’s minimal concern about external moisture migrating to the down. Also, the lesser breathability boosts the temperature rating a small amount.

The choice for wet environments, ‘cowboy camping’ and for users of flat tarps wanting to eliminate the bivy bag. The 7d wp/b is coated fabric, yet has a very light denier count, and as such adds under 5% to the total weight over the 10d option.

Combo of above two: A combination of 10d/15d breathable and 7d wp/b shells. 

With 7d wp/b only covering the outer foot section and top draft collar you can protect the down where it matters the most, while leaving the large mid section fully breathable. For use in the modern single wall tent where rampant condensation often collides with the lower end of sleeping bags. Also, the draft collar is protected from moist exhalations. A very versatile setup.

Look closely at the configuration table below, in order to select precisely what suits your use.

Liner Material Choices

The worst long term wear on quilt fabrics is the inside liner material. If you want to break with ultralight traditions, and risk adding up to 2 ounces (!!) of weight, the Arc UL can be upgraded to our soft, durable 20d Taffeta black liner, specifically developed for sleeping bags.


Besides the custom sourced shell and liner materials, we also consider shock cords, buckles, snaps and other notions as specific targets for UL optimization, further shaving grams. 

What's in the box?

The quilt, a set of quilt straps, a silnylon stuffsack and a large breathable storage sack.

We also have additional articles with helpful pointers on selection and design:

Choosing the right Quilt

Quilt Straps and Cords

Designing with Down


Go to the bottom of this page for the full Arc UL Configuration Menu.

Arc UL 30°F in the stock dark grey 10d shell with upgraded black waterproof/breathable 7d foot and collar.

Arc UL 25°F in the stock purple 10d shell.

Arc UL 20°F in the stock Moroccan blue 10d shell with upgraded black waterproof/breathable 7d foot and collar.

After saving your customized product, remember to add it to your cart.



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Excellent craftsmanship

Can't really say anything else then this is an excellent product. Bought mine 30f a while ago and just got to use it. Even when the temp crept down to the mid too low 20s I was decently warm (with a puffy jacket and base layer). And that from a 30f quilt.

All in all you can really tell the quality of the work gone in to the quilt. My only concern the cord that is used in the edge tension control as well as to cinch around the neck. For me it feels abit thin and I'm uncertain about the longevity, however as of now it works perfectly


Great product by a great company

Not only is the Arc UL I recieved a beautifully made and well thought out quilt, but Nunatak is an awesome company that was a pleasure to work with. The quilt was both built and shipped sooner than projected, and the weight was lighter than advertised. The expectation Nunatak set was handily exceeded in their execution. If that wasn't already more than I could ask for, I emailed with a question the day my order arrived and in less than an hour I was called by Jan to discuss. It was clear over the phone that Nunatak is passionate about the quality of their products and customer experience. I'll be a repeat customer.

  • 1 out of 1 people found this review useful.

Arc UL 20*

This quilt is amazing! So comfortable, amazing workmanship. The tension thing is awesome and works so well! My only gripe is when I made the order, I asked what it would weigh with my specific customization, and was told it would be about 22 oz and its 26.9 oz. I was hoping to get my quilt close to 20 oz so now I may end up buying a 30* version with less features to try and get it close to 20oz. Over all great work on this 5 star quilt.


Beautiful Quilt

My Arc 20 just arrived. Packaged well. Lofted quickly. Colors, stitching, and overall quality is top notch. Absolutely beautiful. Fits perfectly. A great experience on your website building to my specifications. Enjoyed the status updates and delivered well within your listed lead time. Cannot wait to use this on my next trip. A quick shout out to Mittencamper who's video informed me about this bag and company.


The Comforter!

I purchased this quilt, specced to 15 degrees with ultra wide dimensions (78" long x 66" wide) and a great big footbox too (45"). Super roomy for me or plenty to share with a significant other who doesn't have their own nice backpacking gear. I used it on an Arizona Trail thru hike in the Spring of 2017 with nighttime temperatures down to 15 degrees F, and will use it again next year for a CDT thru hike that will entail all kinds of snow and freezing temps. It's enormous, and excessive, and I love it. I call it the Comforter.

Even as excessive as I asked for it to be built via the awesome customization offered by Jan and Nunatak... this 993 gram (35 oz) Comforter (essentially a couple's thru hiking bag), only weighs 2 more ounces than a WM Alpinelite 20 degree in long (33 oz). It's a little bulkier in my bag, yes, but that bulk equals pure warmth, not unnecessary zippers. It's my great big security blanket against the cold windy mountains and snow, and I feel fine. Many thanks for an excellent piece of gear.

  • 2 out of 2 people found this review useful.

Arc UL

Review from March 2016, reprinted with author's permission:

I have now used my quilt for 7 nights in South West Tasmania. It was excellent. Conditions were not that cold (4 deg C) but it was super warm and comfortable. Lumpy down from shipping dissipated. I even felt sorry for my friend who had a regular bag. So - I am very happy with my purchase.

  • 1 out of 1 people found this review useful.

New quilt day!

This review from 04/27/2016 is an excerpt from an email we received, and published here with the author's permission. Nunatak Admin.

I received the quilt yesterday. First things first - I LOVE THE QUILT. There are very few possessions I own that I would never part with under any conditions - this quilt is already 1 of them. 1. The craftsmanship is superb - better than the Specialist I have. As good as western mountaineering or Katabatic. 2. You are properly filling your shells - I feel the shells were underfilled during Tom's ownership. No need for overfill whatsoever. 3. the 2" differential cut is perfect ( I wondered if 4" would be better). This is the most comfortable quilt/bag I've ever experienced. 4. I love the color (I was not expecting to like it) - your photos online are very accurate representation. 5. You delivered in 4 weeks! 6. The drawstring in the middle of the neck baffle is SUPERB - supreme comfort. 7. Footbox is generously filled and baffled. 8. You delivered right on the weight I was expecting - exactly 1lb 10oz (I had to extrapolate from your published numbers) 9. You sent along stickers and a "Birth Certificate" for the quilt. 10. I love the 20 degree so much I may sell my specialist instead of modifying it and purchase a vector from you for summer nights. Ian

  • 1 out of 1 people found this review useful.

New 2 Season Arc Quilt

From an email we received:

I purchased my quilt summer 2016 and have used for ~ 20 nights since. It is considerably warmer than the three season (UK) bag it replaced while also being ~ 30% lighter - a testament to the excellent design and materials. The flexibility and comfort of the quilt it not undersold and I intend to take it trekking in Greece this spring where I will be sleeping at elevations between sea level and 2500 metres. No signs of wear and tear so far. Good service and delivered well ahead of original estimate. No reservations about ordering from Nunatek again.

Kind regards,

Jon Ball

  • 1 out of 1 people found this review useful.

Arc 15F

I ordered a Vector Arc 15 degree bag/quilt. Jan helped me modify the Vector so it opens completely as a quilt and the foot box closes completely with a cord acting as an arc. I added the weather resistant Epic shell with 900 plus fill down and added down insulation. Jan recommended a few inches be added to the Arc. I've used this bag indoors and outdoors every night for the last 6 months. It is perfect as a quilt inside and is wonderful inside a Gortex bivy outside. If you wear a down hooded jacket inside this Vector you will be comfortable in winter conditions. I love it and keep it with me wherever I travel in Oregon. It could be a life saver for me and my wife if we ever ran into a situation where we were stuck in winter conditions. Jan is always helpful whenever I have any questions. Customer service is awesome.


32 deg Quilt

After a long day on the trail I see myself dreaming of climbing into my quilt with its ultralight (15.8oz), ultrasoft feel, snugging around my shoulders. I have been cosy and warm in all conditions down to -1C so far and it is my number one sleeping option. Thank you Jan for your advice in helping me choose the right one for me.


This Quilt will set you FREE

I purchased my Arc UL quilt about a year ago and have nothing but high praise for it. I've used the bag for 55 days of hiking in Alaska, 40 days in the Grand Canyon, and a week of hithhiking/trainhopping in between. The quilt has been soaked, dragged, stuffed and generally abused constantly, and does not show a single sign of wear. It is insanely warm (20 degree), unbelievably warm, and ridiculously compact. Nunatak could charge twice as much for these wonders and it would be worth every penny. Do yourself a favor, buy one and never worry about a cold night again. Thank you for the worlds lightest mobile home Nunatak!


Quilt & Jacket

Review from 05/05/2016:

Jan, The quilt and jacket arrived safely at my door step. Never have I received so large a box weighing so little, and with such wonderful things inside. They are absolutely perfect. Thank you so much for your excellent work. I really appreciate it. -Niles

  • 2 out of 4 people found this review useful.


Review from 07/26/2016:

Loved that Arc quilt in Colorado !! Getting the Nano quilt for the JMT - you guys are great . Thanks !!

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Arc UL  Three Season

Arc UL Three Season

Ordering closed until mid August. See top banner

The Arc UL quilts are designed for optimal efficiency in the environments met by long distance hikers.

Custom features including sizing and weight saving options.

Product Options
Temperature Rating

The rating reflects the lowest temperature during which a well conditioned hiker can expect to remain comfortable throughout a full night. Adequate shelter and ground pad must be used.

30°F / 0°C. Includes differential cut
25°F / -4°C. Includes differential cut
20°F / -7°C. Includes differential cut
Inside Length
To determine the correct length please refer to the measurements in the chart.
Shoulder Width
Measure around your widest part, including arms. Add 8-12” to this number for the best performance.
50" Our narrowest size for slim folks who doesn’t toss and turn much; and experienced quilt users wishing to save weight.
56" The most popular size that fits most frames.
62" For bigger people and/or those who toss and turn.
68" Very wide quilt - sprawling coverage!
Footbox Size Circumference
40" is the male size 10-11 shoe standard. For side sleepers the 40" is good to size 12-13
Shell Material

Two options: Ultralight 10d for the lightest, most breathable and best lofting performance. 15d for more durability and tear resistance with only a small weight penalty.

Waterproof/Breathable Shell Options

This selection substitutes a black 7d waterproof/breathable shell fabric to the lower third of the quilt, plus the top neck/head opening. The large torso middle section remain with the classic 10d/15d breathable fabric.

Liner Material Options
Choose between lightest - the 10d - or long lasting comfort at the penalty of several ounces extra weight: the 20d
Down Type

We use 900 fill power goose down, certified responsibly sourced.

Hyper-Dry moisture resistant down will help combat the effects of perspiration, misting tents and damp air. Nunatak products made with Hyper-Dry down will have a slight increase in bulk over those made with untreated down.

Edge Tension Control

This design involves two user adjustable shock cords running lengthwise along the left and right quilt edges. On cold nights tension the cords to shorten the edges and draw them under you; during milder conditions completely slacken the cords to have the blanket throw feel. Go here for more info

Strap package

Straps snug the quilt around you and/or the sleeping pad. Go here for more info

Down Overfill
Adding overfill can prolong the life of the down, help maintain loft during moist conditions, boost the temperature rating by a small amount and keep the down volume from shifting. The amount depends on the product, the size and the rating.
No Thanks
Overfill in foot section
Overfill in torso section
Overfill evenly throughout
Optional Fully Integrated Apex Over Quilt

50°F synthetic filled Apex over-quilt providing a rating boost of 12-15°F. It is custom cut to fit over the Arc UL without compressing the down insulation, and provides 6-8 integration points to hold the two together. Average weight is 16-18 ounces. Black 10d inside and out with a sewn closed mummy style footbox. Drawcord at the top, ETC system.

No Thanks!
Yes, include a custom 50°F Apex over-quilt
Stuff Sack
Our stuff sacks are pretty dope, but current weight saving trends in ultralight circles eschews this once crucial item. So, opt out and save $ while also being very current.
No stuff sack
Yes, please include a stuff sack
Your Measurements
Optional: Fill in the blanks to ensure getting the best fit. No changes will be made to your size selections without approval
Shoe Size