Arc UL 20°F - 15°F

New product

Due to move this product is unavailable until late 2022.

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.

More details


Add to wishlist

Pay via Credit Card or Paypal Account
Pay via Credit Card or Paypal Account

Due to move this product is unavailable until late 2022.

A few things to keep in mind:

  1. We measure the actual width from the finished quilt's inside, without stretching. 
  2. The differential cut makes the inside narrower/shorter than the outside.
  3. Our sizes are real life, so will get you a quilt generally wider/longer than other brands with similar specs.
  4. The measured length does not include the draft collar.

Appropriate use

These quilts are designed to provide sleeping comfort in the western US mountains from April to October. 

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.

With the 15°F quilt cold sleepers get a boost in loft.

30°F and 25°F quilts are available here

Fill and Loft

The 900 fp down loft is a between 2.80 and 3.25.  Fill volumes for either level are detailed in the charts.


The length is in 4" increments. The chart numbers interprets where the quilt top is 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 size up if in doubt. Bags and quilts cut too short tends to compress the foot area insulation to the detriment of cold toes.

Adequate width in the shoulder to hip region is crucial for sleep comfort and draft control. A ball park figure to achieve optimal performance is your shoulder circumference plus 6"-10". The Arc UL does not taper inwards until below hip level.

Newcomers to backcountry quilts can also experiment with a blanket before committing to a width. 

Foot End Design

The traditional Arc design is a permanently closed section finished with a round bottom piece sewn in place. A design common with high-end mummy bags.

Shell Material Choices

More details on the Fabric Page, found in the top menu under Materials.

Ultralight: 10d ultralight breathable shell. 

This ultralight fabric creates a comfortable sleep environment at the lowest weight. While providing very little protection from moisture, the superior breathability allows it to dry quickly in the sun. Ideal for users seeking the lowest weight.

Classic: 15d lightweight breathable shell.

Same non-existent moisture protection as the 10d above, but a significant increase in durability and tear strength. Expect a weight gain up to one ounce, depending on size.

Moisture protection for select areas: 7d ultralight waterproof/breathable shell.  

With 7d wp/b covering the outer foot section and top draft collar you can protect the down where it typically wets out 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.

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.

Liner Material Choices

Long term wear on quilt fabrics is most pronounced on the inside liner material. To anticipate this the Arc UL can be upgraded to our soft, durable 20d Taffeta black liner, specifically developed for sleeping bags. Expect one ounce of weight gain.


This optional synthetic Apex insulated bag is a booster option for extending the use of your quilt well into the colder season, while providing superior moisture management. 

Depending on the user the overbag can add 15°F or more to the rating of your base quilt, while completely eliminating drafts. The latter is probably the most crucial element for a winter specific quilt based sleep system; and very hard to maintain with a quilt/quilt setup.

The dampness inevitably forming on the outer surface will mostly affect the quick drying synthetic while the down mass stays drier. This applies to body moisture pushed outward; and dew, frost and shelter induced condensation from the environment. For longer trips in inclement conditions this becomes a crucial aspect of staying warm. 

This overbag is zipper-less with a closed mummy style foot box, and features a custom cut to match your quilt sizing specs and curvature thus avoiding excessive compression of the lofted down. A draw cord at the top seals in the warmth. It uses 2.5 oz weight Apex. 

The fabric used is a highly breathable 10d nylon, with smooth taffeta inside and ripstop out. All black. Average weight is 15oz, with small variances depending on the base quilt.

Additional applications includes emergency and summer stand alone use.

The overbag is also available for purchase at a later day here

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

Designing with Down


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

Forest 10d shell with upgraded grey waterproof/breathable 7d foot and collar.

Purple 10d shell with upgraded grey waterproof/breathable 7d foot and collar.

Grey 10d shell with upgraded grey waterproof/breathable 7d foot and collar.

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



* required fields


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.

  • 0 out of 1 people found this review useful.

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 !!

Write your review!

Write a review

Arc UL 20°F - 15°F

Arc UL 20°F - 15°F

Due to move this product is unavailable until late 2022.

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.

20°F / -7°C. Includes differential cut
15°F / -10°C. Includes differential cut
Inside Length

To determine the correct length please refer to the measurements in the chart.

In betweener? Use this link

Shoulder Width

Measure around your widest part, including arms. Add 8-12” to this number for the best performance.

Wanting more options? Go here

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 7d waterproof/breathable shell fabric to the lower third, plus the head opening. The large torso middle section remain with the classic 10d/15d breathable fabric.

No Thanks!
Grey Robic Weatherproof 7d - Applied Only to Lower Third and Top Draft Collar
Liner Material Options
Choose between lightest - the 10d - or long lasting comfort at the penalty of several ounces extra weight: the 20d
Black 10d taffeta - Lightest, most breathable
Black 20d taffeta - Durable, soft and comfortable but about an ounce heavier!
10d black taffeta in torso section, more durable 20d taffeta in foot section
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.

Strap package

Straps snug the quilt around you and/or the sleeping pad.

Yes, include pad attach and under-body straps
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 Custom Sized Apex Overbag

50°F synthetic filled Apex over-bag providing a rating boost of 15°F.  It is custom cut to fit over the Arc UL without compressing the down insulation. Average weight is 18 ounces. Black 10d inside and out with a top draw cord.

No Thanks!
Yes, include a custom 50°F Apex over-bag
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