Western Mountaineering UltraLite 20Deg
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The Western Mountaineering UltraLite is a 20°F (-7°C) down mummy sleeping bag built for three-season backpacking. In the 6'0" size it weighs 1 lb 13 oz, holds 16 oz of 850+ fill power goose down, and packs to 7"x13". It is made in the USA.
Twenty degrees. Under two pounds. That is the short version, and for a lot of backpackers it is the whole conversation. Western Mountaineering builds the UltraLite for people who count ounces and still want a warm night when the temperature drops after dark. It is a spring-through-fall bag for long miles, the kind of trip Western Mountaineering points at trails like the John Muir Trail and the Colorado Trail.
Western Mountaineering UltraLite specs
| Spec | 5'6" (165 cm) | 6'0" (180 cm) | 6'6" (200 cm) |
|---|---|---|---|
| Total weight | 1 lb 12 oz (795 g) | 1 lb 13 oz (820 g) | 1 lb 15 oz (880 g) |
| Down fill weight | 15 oz (425 g) | 16 oz (455 g) | 17 oz (480 g) |
| Inside girth, shoulder / hip / foot | 59" / 51" / 38" (150 / 130 / 97 cm) | 59" / 51" / 38" (150 / 130 / 97 cm) | 60" / 52" / 38" (152 / 132 / 97 cm) |
| Stuff size | 7" x 13" (18 x 33 cm) | 7" x 13" (18 x 33 cm) | 7" x 13" (18 x 33 cm) |
| Temperature rating | 20°F / -7°C (Western Mountaineering rating) |
|---|---|
| Shape | Mummy with full collar |
| Insulation | 850+ fill power goose down, continuous baffles |
| Loft | 5.5" (14 cm) |
| Shell fabric | 12 denier ripstop nylon (ExtremeLite) |
| Zipper | Full-length #5 YKK with insulated draft tube |
| Included | Ultralight stuff sack and breathable storage bag |
| Color | Royal Blue / Black |
| Made in | USA |
Sizes and zipper sides in stock vary. Pick yours in the options above, and call or message the store if you do not see the one you need.
Who the UltraLite is for
- Thru-hikers and weekend backpackers who want one bag for spring, summer and fall nights down into the 20s.
- Weight-counters who would rather carry less and wear a layer than carry a heavier bag.
- Anyone shrinking their pack. At 7"x13" it takes up very little room.
Who should look at something else
- Cold sleepers or high-elevation camps. Western Mountaineering says to pick a bag rated 5-10°F colder than the lowest temperature you expect if you sleep cold. Look at the 10°F VersaLite.
- Side sleepers and restless sleepers. The UltraLite is a mummy cut. The 35°F DreamLite has a roomier cut and opens flat like a quilt.
- Warm-weather trips. The 32°F SummerLite and 35°F HighLite weigh less.
- Mostly car campers. You will not get much for the weight savings you are paying for.
What makes it warm and light
- 850+ fill power goose down. High fill power means more loft for the weight, so the bag is warm without being heavy. Western Mountaineering says its down is ethically sourced.
- Insulated draft tube. A down-filled tube runs along the zipper to block cold air where bags usually leak heat.
- Full insulated collar and cinching hood. The collar seals warmth around your shoulders, and the hood pulls tight when the temperature drops.
- Continuous baffles. The down is not locked into sewn chambers, so you can shift it toward the top for more insulation on colder nights.
- 12 denier ripstop nylon shell. It is light and tightly woven. It helps keep moisture out while letting body moisture escape.
- Full-length #5 YKK zipper. A lightweight zipper that runs smoothly.
How to choose your size
The UltraLite is a mummy bag, so the cut is snug on purpose. A snug bag has less empty space to heat. Check the girth numbers in the table above: at 6'0" the bag measures 59" at the shoulders, 51" at the hips and 38" at the foot. If you are between sizes, or you sleep with a lot of layers or like room to roll, ask us before you order.
UltraLite vs. other Western Mountaineering bags (6'0" size)
| Bag | Rating | Total weight | Down fill | Loft | Packs to | Best for |
|---|---|---|---|---|---|---|
| SummerLite | 32°F / 0°C | 1 lb 3 oz | 9 oz | 4" | 6" x 12" | Warm-weather hiking and bikepacking |
| HighLite | 35°F / 2°C | 1 lb | 8 oz | 3.5" | 6" x 12" | Lightest option for warm nights |
| DreamLite | 35°F / 2°C | 1 lb 9.5 oz | 13 oz | 4" | 7" x 13" | Side sleepers; roomier cut that can open flat |
| UltraLite | 20°F / -7°C | 1 lb 13 oz | 16 oz | 5.5" | 7" x 13" | Three-season backpacking, one bag for most trips |
| VersaLite | 10°F / -12°C | 2 lb | 20 oz | 6.5" | 8" x 15" | Cold-weather and shoulder-season backpacking |
The UltraLite sits in the middle of the line: about 13 oz heavier than the 35°F HighLite for 15°F more warmth, and 3 oz lighter than the VersaLite for 10°F less. If you are on the fence, ask us.
What to pair it with
- A sleeping pad rated R-5 or higher. Western Mountaineering's temperature rating assumes a properly insulated pad (about R-5 or better for colder conditions) and dry base layers. See our sleeping pads.
- A pillow and a liner for comfort and to keep your bag cleaner between washes. See our pillows.
- A pack with room to spare. Browse backpacking packs.
UltraLite questions
What temperature is the UltraLite rated for?
It is rated to 20°F (-7°C). Western Mountaineering calls its ratings a guideline for comparing bags, not a comfort guarantee. It says the rating usually falls between the "limit" and "comfort" figures from standard EN/ISO testing, and recommends treating it as the lowest temperature you realistically expect. If you sleep cold, they suggest choosing a bag rated 5-10°F colder than that.
Is the UltraLite a winter sleeping bag?
No, it is a three-season bag. For regular nights well below 20°F, look at a colder-rated bag like the 10°F VersaLite. Western Mountaineering also offers an overfill option that adds roughly 5°F of warmth, but it is a custom order.
How much does the UltraLite weigh and how small does it pack?
In the 6'0" size it weighs 1 lb 13 oz (820 g) and packs to about 7" x 13". The 5'6" weighs 1 lb 12 oz and the 6'6" weighs 1 lb 15 oz. All three sizes pack to the same stuff size.
What size should I buy?
Western Mountaineering makes the UltraLite in 5'6", 6'0" and 6'6". Choose a length based on your height, and check the girth numbers above for shoulder and hip room. A mummy bag fits closely, so if you want extra room, ask us or look at the DreamLite.
What sleeping pad should I use with the UltraLite?
Western Mountaineering's rating assumes an insulated ground pad, about R-5.0 or higher for colder conditions, plus dry base layers and socks. For summer and shoulder-season trips they suggest roughly R-3 to R-5.
Is the UltraLite waterproof?
No. The 12 denier ripstop shell is tightly woven and helps keep moisture out while letting body moisture escape, but it is not a waterproof bag. Like any down bag, it sleeps best when dry, so keep it in a dry bag or a pack liner on the trail.
How do I wash and store the UltraLite?
Western Mountaineering suggests laundering the bag after a season of regular use. Dry it in a front-loading dryer on low heat, or on no heat or low heat with clean tennis balls, to restore loft. Store it loose in the breathable storage bag, not compressed in the stuff sack, in a cool, dry place away from sunlight.
Does the UltraLite have a warranty?
Yes. Western Mountaineering covers manufacturer defects for the life of the bag. Normal wear and misuse are not covered: a broken stitch is covered, a field rip is not. Most repairs, including tears and zipper problems, are done at their factory in San Jose, California.
Where is the UltraLite made?
It is made in the USA by Western Mountaineering.
Why buy from Quest Outdoors?
Quest has been an outdoor gear store in Louisville, Kentucky since 1984. You can talk to people who know the gear, and Western Mountaineering sleeping bags ship free by ground.
