Head-to-head · Best 0 Degree Sleeping Bags

Mountain Hardwear Phantom 0F/-18C vs Therm-a-Rest Parsec 0F/-18C

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

The short answer

Therm-a-Rest Parsec 0F/-18C comes out ahead by a narrow margin (4.2 vs 4.5). The gap is mostly about Weight- and budget-conscious winter backpackers who want a genuinely light 0°F down bag and sleep on the warmer side. — read the strengths below before deciding.

Ranked #5 in Best 0 Degree Sleeping Bags

Mountain Hardwear Phantom 0F/-18C

4.2

$700as of Jun 7

The Phantom 0 is a polarizing bag: CleverHiker calls it 'one of the warmest backpacking sleeping bags we've tested' while OutdoorGearLab found it 'freezing all night' at zero degrees. It pairs a light 800-fill build with a buttery-soft 20D shell and a narrow, weight-efficient cut. Real owners on Trailspace report comfort to 2°F, so fit and individual metabolism clearly matter with this one.

Strengths

— Excellent warmth-to-weight ratio in a roughly 2 lb 11 oz package
— Smooth, soft 20D nylon taffeta shell that's pleasant against skin
— Massive draft tubes and effective hood cinches to seal in heat

Watch-outs

— OutdoorGearLab tested it 'freezing all night' at 0°F and scored it 56/100
— Thin shell fabric can let feathers shift and create cold spots
— Narrow cut feels restrictive for stomach and starfish sleepers

$700 · Buy at mountainhardwear.com Full review →

Higher ratedRanked #3 in Best 0 Degree Sleeping Bags

Therm-a-Rest Parsec 0F/-18C

4.5

$530

The Parsec 0F is the warmth-to-weight champion of this group, at 2 lb 6 oz one of the lightest true 0°F down bags you can buy. Reviewers across The Trek, Advnture, and SectionHiker praise its loft and value, though it uses 800-fill down and at least one cold-test reviewer found its honest comfort floor closer to 5°F than 0°F. At around $530 it badly undercuts the premium bags here.

Strengths

— Outstanding warmth-to-weight ratio at just 2 lb 6 oz for a 0°F bag
— 800-fill Nikwax Hydrophobic Down resists moisture and dries faster
— Box-baffled, body-mapped 60/40 down distribution puts insulation where it counts

Watch-outs

— Still expensive at $490-$570 in absolute terms
— One real-world cold test recommended a 5°F practical floor, not 0°F
— Cold sleepers and women may find the honest comfort closer to 10°F

$530 · Check Price on Amazon Full review →

How they stack up

Mountain Hardwear Phantom 0F/-18C

The most divisive bag here, lighter than the Western Mountaineering Kodiak MF and Feathered Friends Ibis ES 0 but with sharply split warmth verdicts, and less of a sure thing than the Therm-a-Rest Parsec 0F or the ultralight Sea to Summit Spark 0F.

Therm-a-Rest Parsec 0F/-18C

The lightest and best-value true 0°F bag here, beating the Western Mountaineering Kodiak MF, Feathered Friends Ibis ES 0 and Mountain Hardwear Phantom 0 on warmth-to-weight and price, though it uses lower 800-fill down than the Kodiak and Ibis and is heavier than the Sea to Summit Spark 0F.

Specs side-by-side

Spec	Mountain Hardwear Phantom 0F/-18C	Therm-a-Rest Parsec 0F/-18C
Temperature Rating	0°F limit / 13°F comfort	0°F limit / 14°F comfort (ISO)
Fill Power	800-850 goose down	800 Nikwax Hydrophobic goose down
Fill Weight	2.04 lb	—
Total Weight	2 lb 11 oz - 3 lb (long)	2 lb 6 oz (1.09 kg)
Shell	20D nylon taffeta	—
Cut	Narrow mummy	—
Features	Draft tubes, hood cinches	—
Warranty	Limited lifetime	Limited lifetime
Baffles	—	Box-baffled, 60/40 body-mapped
Length	—	Regular 80 in
Extras	—	Pad straps, external quilt loops
Zipper	—	Two-way YKK side zip

← See the full ranking of best 0 degree sleeping bags