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Western Mountaineering UltraLite 20 Review
Looking for a premium 3-season sleeping bag that delivers exceptional warmth without the bulk? In this Western Mountaineering UltraLite 20 review, we break down why this ultralight down bag is one of the most trusted choices for backpackers seeking warmth, packability, and durability.
The Western Mountaineering UltraLite 20 is a 20°F-rated mummy sleeping bag filled with 850+ fill power ethically sourced goose down. Weighing just 1 lb 13 oz, it provides outstanding warmth-to-weight performance. Its slim cut, full-length zipper with draft tube, and continuous baffle construction make it efficient in retaining body heat while staying breathable.
What sets this bag apart is the high-quality materials and craftsmanship. The 12D ExtremeLite shell fabric is both lightweight and durable, while the down is lofted to perfection for maximum insulation. Whether you’re backpacking in the Rockies or thru-hiking the PCT, this bag is a go-to for serious backpackers who need warmth without compromise.
Key Specifications
| Weight | 1 lb 13 oz (regular) |
| Temperature Rating | 20°F (-6°C) |
| Insulation Type | 850+ Fill Power Goose Down |
| Shell Material | 12D ExtremeLite Nylon |
| Zipper | Full-Length with Draft Tube |
| Shape | Mummy |
| Stuffed Size | 6" x 12" |
Comparisons
Western Mountaineering UltraLite 20 vs Feathered Friends Hummingbird YF 20
The Feathered Friends Hummingbird YF 20 is a close rival in warmth, fill power, and craftsmanship. Both bags use 850+ fill down and weigh under 2 pounds. However, the Western Mountaineering UltraLite 20 has a slightly trimmer fit and smaller packed size, making it a better choice for minimalist packers. The Hummingbird offers a roomier footbox and slightly more interior space, so it’s ideal if you move around more at night. Both are exceptional — it comes down to your fit preference.
Western Mountaineering UltraLite 20 vs Therm-a-Rest Parsec 20
The Therm-a-Rest Parsec 20 is a more affordable option that still delivers solid warmth and a good warmth-to-weight ratio. It uses 800-fill Nikwax Hydrophobic Down and has a roomier cut for added comfort. While it’s heavier and bulkier than the Western Mountaineering UltraLite 20, it includes features like zoned insulation and a water-resistant footbox. Choose the UltraLite for maximum performance and minimalism, and the Parsec if you want comfort with a lower price tag.
Pros & Cons Summary
| Feature | WM UltraLite 20 | Feathered Friends Hummingbird 20 | Therm-a-Rest Parsec 20 |
|---|---|---|---|
| Weight | ✅ Ultralight | ✅ Ultralight | ❌ Heavier (2 lb 4 oz) |
| Warmth | ✅ Excellent | ✅ Excellent | ✅ Good |
| Packability | ✅ Highly compressible | ✅ Very packable | ❌ Bulkier |
| Comfort | ✅ Trim but snug fit | ✅ Roomier footbox | ✅ Relaxed cut |
| Durability | ✅ High-end materials | ✅ Premium build | ✅ Good value |
| Best For | Ultralight backpackers | Cold sleepers with extra space | Budget-conscious hikers |
Looking for the right sleeping bag for your outdoor adventure? Visit our Best Sleeping Bags guide.
Frequently Asked Questions
Is the UltraLite 20 true to its temperature rating?
Yes — this bag is known for having an accurate comfort rating, especially when paired with an appropriate sleeping pad.
Can it be used for thru-hiking?
Absolutely. It’s a popular choice on trails like the PCT and CDT due to its weight, warmth, and durability.
Does it include a compression sack?
It comes with a stuff sack and storage sack, but not a compression sack. You may want to purchase one separately.
Is it treated with water-resistant down?
No, Western Mountaineering uses untreated down to maintain loft and longevity. The shell provides decent water resistance, but it’s not waterproof.
What size should I get?
The regular fits up to 6’0”, the long fits up to 6’6”. Choose based on your height and preference for space.
Final Thoughts
The Western Mountaineering UltraLite 20 is an elite sleeping bag built for lightweight performance without sacrificing warmth or durability. With its top-tier down fill, premium construction, and impressive compressibility, it’s a top choice for serious backpackers and long-distance hikers. If you want one of the best 3-season bags on the market, the UltraLite 20 should be on your shortlist.
