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Head-to-head · Best 0 Degree Sleeping Bags

Feathered Friends Ibis ES 0 vs Sea to Summit Spark 0F

Which is the better buy? Side-by-side on rating, price, strengths, and watch-outs — with the published ratings we averaged to get there.

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The short answer

Feathered Friends Ibis ES 0 comes out ahead by a narrow margin (4.6 vs 4.4). The gap is mostly about Winter campers in cold, wet, or condensation-prone conditions who want a conservatively rated bag and will pay top dollar for a waterproof shell. — read the strengths below before deciding.

Feathered Friends Ibis ES 0
Higher ratedRanked #1 in Best 0 Degree Sleeping Bags
Feathered Friends Ibis ES 0
2 sourcesall derived$859as of Aug 1

The Ibis ES 0 pairs 900+ fill power goose down with a waterproof-breathable Pertex Shield EX shell, which makes it the bag to beat for cold, damp winter conditions. Feathered Friends rates conservatively, so its 0°F sits closer to a true comfort rating than a survival limit. It is the widest of the brand's zero-degree bags, and also among the heaviest here at 3 lb 2 oz.

Strengths
  • — 900+ fill power goose down, the highest-loft insulation in this group
  • — Waterproof-breathable Pertex Shield EX shell handles condensation and damp tents
  • — Conservative 0°F rating means real-world comfort at the stated temperature
Watch-outs
  • — Heavy for a 0°F down bag at 3 lb 2.4 oz for the regular
  • — List price of $859 puts it at the top of the category
  • — Waterproof shell adds weight and slightly less breathability than open nylon
$859 · Buy at featheredfriends.comFull review →
Sea to Summit Spark 0F
Ranked #2 in Best 0 Degree Sleeping Bags
Sea to Summit Spark 0F
3 sourcesall derived$679as of Aug 1

The Spark 0F is the ultralight of this group, packing a genuine 0°F-rated bag into about 2 lb 7 oz and a sub-10-liter stuff size. It uses 850+ fill Ultra-Dry down, and reviewers find its temperature rating accurate. Against that: a snug, less-forgiving cut, a thin shell offering little wet-weather protection, and a steep price for the warmth.

Strengths
  • — Among the lightest 0°F down bags at roughly 2 lb 7 oz
  • — Sub-10-liter packed size, the most compressible bag here
  • — 850+ fill power Ultra-Dry treated goose down resists moisture
Watch-outs
  • — Snug ultralight cut is less forgiving than the Kodiak or Ibis
  • — Thin shell offers little wet-weather protection
  • — Pricey at roughly $649-$679 for the warmth delivered
$679 · Check Price on AmazonFull review →

Derived means the reviewer published no score, so one was inferred from their written verdict. Everything else is a number the publisher printed. How we rank.

How they stack up

Feathered Friends Ibis ES 0

The highest-loft and most weather-resistant bag here thanks to 900+ fill and a Pertex Shield EX shell, rivaling the Western Mountaineering Kodiak MF for warmth but heavier than it, the Mountain Hardwear Phantom 0, the Therm-a-Rest Parsec 0F and the Sea to Summit Spark 0F.

Sea to Summit Spark 0F

The lightest and most compressible bag here, undercutting the Therm-a-Rest Parsec 0F on weight and packed size and far lighter than the Western Mountaineering Kodiak MF, Feathered Friends Ibis ES 0 and Mountain Hardwear Phantom 0, but with a snugger cut and a thin, less weatherproof shell.

Specs side-by-side

SpecFeathered Friends Ibis ES 0Sea to Summit Spark 0F
Temperature Rating0°F (-17.7°C) comfort0°F limit / 14°F comfort
Fill Power900+ goose down850+ Ultra-Dry goose down
Fill Weight1 lb 15.2 oz (884 g)29.6 oz (840 g)
Total Weight3 lb 2.4 oz (1429 g)2 lb 7 oz (1113 g)
ShellPertex Shield EX waterproof-breathableUltralight nylon
Shoulder Girth59 in—
Packed Size17 L9.9 L
OriginMade in Seattle, USA—
Zipper—Full-length YKK with draft tube
Cut—Snug ultralight mummy
Material—Nylon
Dimensions—83.1"L x 52.8"W
← See the full ranking of best 0 degree sleeping bags