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Western Mountaineering NanoLite 38F — Specs & Analysis
Manufacturer specifications, compared against every other sleep systems in our database. We do not test gear in the field — we measure, verify, and compare.
Western Mountaineering's NanoLite uses their premium 850+ fp goose down in a continuous baffle design that eliminates cold spots. The ExtremeLite shell fabric is whisper-thin at 10D, and the half-zip design saves weight while still allowing ventilation. Made in San Jose, California.
Who Is the Western Mountaineering NanoLite 38F Best For?
Warm-weather bikepackers who want premium down performance in a featherweight package. If that describes your riding style, the NanoLite 38F should be at the top of your shortlist. It sits in the Sleep Systems category alongside 19 other products we track.
How It Compares
At 370g and $305, the NanoLite 38F is 120g heavier than the lightest option in this category (the Therm-a-Rest NeoAir UberLite at 250g). The most budget-friendly option is the Cascade Designs Therm-a-Rest Z Lite Sol at $50.
The price-to-weight ratio comes in at $82 per 100g — a premium price point, but you're paying for quality, materials, and design that justify the investment for serious bikepackers.
What We Like
- +Premium 850+ fill power goose down
- +Continuous baffle design eliminates cold spots
- +Extremely packable with ultralight shell fabric
- +Made in USA with excellent quality control
Watch Out For
- −Mummy shape feels restrictive for side sleepers
- −38F rating is optimistic for cold sleepers
- −Not water-resistant — keep it dry
The Bottom Line
We haven't scored the Western Mountaineering NanoLite 38F, and neither has anyone else we can cite. It's here for its verified specifications and dimensions, which is what the fit tools run on — a score is an editorial judgement, and we don't hand one out until someone has a basis for it. What this page can tell you is measured: 370g, $305, and how both sit against every other sleep systems product we track.
Weight checked against the manufacturer on 18 August 2026 — see the source.
Specifications and dimensions come from the sources listed above. Where a page draws on first-hand riding, it says so.
What it packs down to
Western Mountaineering publishes a packed size of 6 x 8 in, which is 3.7 litres as a stuff sack. Of the 55 bags we track that publish a capacity, 37 have room for it and 18 do not.
Volume is computed from Western Mountaineering's own packed size, treating a two-dimension figure as a stuff sack. Bag capacities are the makers' published figures, not ours — 12 of the bags we hold dimensions for publish no capacity and are left out of the count rather than assumed. A stuff sack does not reshape itself, so read the headroom as room to spare rather than a guarantee it goes in easily.
How it compares
Against the 20 sleep systems we hold published specs for.
At 370g the NanoLite 38F is lighter than 13 of 19 alternatives we track. The category median is 465g.
At $305 it undercuts 4 of 19 of them, against a median of $235. That works out at $82 per 100g — above the $51 median for sleep systems.
Weight and price come from published specifications. Cost per 100g is a blunt measure — it rewards light gear and says nothing about durability or whether the thing works — so treat it as one input, not a verdict.
More in Sleep Systems
Sleeping bags, quilts, and pads that pack small and keep you warm on the trail.