Find Your Store
Home Page

Cart, contains 0 items

When autocomplete results are available use up and down arrows to review and enter to select. Touch device users, explore by touch or with swipe gestures.
Expert Help
Earn Rewards

Western Mountaineering
UltraLite Sleeping Bag: 20F Down

5 out of 5 stars
5 Reviews
$600.00 - $635.00
Color:Royal Blue



Why We Like The UltraLite Sleeping Bag

The Western Mountaineering UltraLite Sleeping Bag lives up to its name by keeping our backpacks light while still packing in a hefty dose of premium 850-fill down for those chilly nights. A soft taffeta lining caresses trail-weary skin and, thanks to the ExtremeLite shell's breathability, the climate inside of the bag stays comfortable on balmier nights.


  • 20-degree sleeping bag weighs less than two pounds for backpacking
  • 850-fill down insulation is extremely lofty and packable
  • ExtremeLite shell has a high thread count for a boost in durability
  • Interlocking draft tubes and a down-filled collar batten down the hatches
  • Mummy shape with slightly narrower shoulders for warmth retention
  • Item #WES0031
[face fabric] ExtremeLite, [lining] nylon taffeta
850+ fill down
Max User Height
5ft 6in, 6ft, 6ft 6in
Shoulder Circumference
[5ft 6in, 6ft] 59in, [6ft 6in] 60in
Hip Circumference
[5ft 6in, 6ft] 51in, [6ft 6in] 52in
Foot Circumference
Bag Length
5ft 6in, 6ft, 6ft 6in
Draft Tube
Pad Retainer
Fill Weight
European Norm/ISO Comfort Rating
European Norm/ISO Lower Limit Rating
Storage Sack
Stuff Sack
Stuff Size
7 x 13in
Claimed Weight
[5ft 6in] 1lb 12oz, [6ft] 1lb 13oz, [6ft 6in] 1lb 15oz
backpacking, camping
Manufacturer Warranty

Overall Rating

5 based on 5 ratings

Review Summary

1 Stars - 0 reviews
2 Stars - 0 reviews
3 Stars - 0 reviews
4 Stars - 0 reviews
5 Stars - 5 reviews

Fits True To Size

Screen reader users: the following list provides a visual scale to illustrate the product fit. Please refer to the heading above for the fit type in text.
Runs smallTrue to sizeRuns large

What do you think about this product?


Selecting an option will reload the available reviews on the page
5 out of 5 stars

April 7, 2023

Big upgrade!

I've used it once or twice and have initial impressions
Size Bought:
5,6 right zip
5' 2"

New into backpacking, I had a not so great sleeping bag which wasn’t warm at all when it was 40F outside and super windy, I didn’t want to be cold again. I did a lot of research and narrowed it down to this bag and I’m so glad I invested in such a quality product! I stayed so warm in 28F with minimal layers on like a warm cozy cocoon. Love that this is made in America by one single person! Don’t hesitate to invest in this sleeping bag you won’t regret it! I wish they had this in a dog version so I can match with my pup.

Stephanie S
5 out of 5 stars

March 12, 2021

Lives up to the hype

I've used it several times

It feels kind of pointless to write another 5 star review of this bag. But it lives up to the hype. Very warm, well made, light, packable, very puffy, comfy and made in the good ol' USA.

5 out of 5 stars

November 26, 2020

I'm big, 6 ft 225 broad shoulder

I've put it through the wringer
Size Bought:
Large Long

I never thought i would get used to a mummy bag but I did, especially when it got cold. 20 degrees out and I was roasty toasty in my ultra light western mountaineering sleeping bag. Seriously, when everyone got up and crawled out of their tents someone said he was freezing all night long, another agreed then looked at me and the other guy. I said I was warm as could be and the other said he was ok but put another shirt on. Then he said I must have had a load a clothes on too. I said nope, just my shorts thats it. It really did hit 20 degrees around 5:30 am and I was absolutely comfortable tucked into my bag. I was wonderfully warm. Hearing how the others were not so warm and miserable I felt really good about doing cold weather hiking with my choice of sleeping bags. It,s warm, very lite weight and stuffs down darn near to about a football size.

Peter N
5 out of 5 stars

October 22, 2020

Best so far!

I've used it several times
Size Bought:
6ft 6in
6' 2"

Best sleeping bag so far! Perfect for 3 seasons and super lightweight. Does not come with compression bag, but that is an easy fix! 11l compression bag fits perfect!

5 out of 5 stars

September 6, 2020

No comparison

I've put it through the wringer
5' 7"

This bag is the perfect mix of warm and lightweight for 3-4 season sleeping. There is simply nothing bad about this bag. WM is the best.