There is a specific kind of misery that comes from being cold in a sleeping bag at 3am, too tired to get up and too cold to fall back asleep, lying there doing the math on how many hours until the sun comes back. I have been there more than once, and it was almost always because I brought the wrong bag for the season. Your sleeping bag is the one piece of kit that quietly decides whether camp is a refuge or a sentence.
Bikepacking spans everything from sweaty July valley nights to frost-cracking alpine cols, and no single bag covers all of that, which is why this list runs from a 45F summer bag all the way down to 0F deep-winter mummies. Every pick here is down, because down still beats synthetic on warmth-for-weight and packed size, the two things that matter most when your whole house rides on the bike. We rated each one on weight, comfort, packability, and value (on our meters, a higher weight score means a lighter bag). Whatever you choose, pair it with a warm sleeping pad and a solid shelter, because a great bag on cold ground still sleeps cold.
Prices run from about $190 for a budget 20F down bag up to $780 for a premium 0F winter mummy (all prices in USD, pulled from brand MSRPs). Summer riders can travel light and cheap, three-season tourers have the most options and should weigh comfort against grams, and the winter crowd pays for warmth in both dollars and pack space. Let's dig in.
| Name | Temp Rating | Fill Power | Weight (regular) | Price |
|---|---|---|---|---|
| Sea to Summit Spark (45F) | 45F / 7C | 850+ | ~365 g | $349 |
| Kelty Cosmic Down 20 | 20F / -7C | 550 | ~1105 g | $190 |
| Exped Terra 15 | 15F / -10C | 650 | ~1245 g | $260 |
| REI Co-op Magma 30 | 30F / -1C | 850 | ~565 g | $349 |
| Nemo Disco Endless Promise 30 | 30F / -1C | 650 | ~950 g | $280 |
| Therm-a-Rest Hyperion 20 | 20F / -6C | 900 | ~567 g | $470 |
| Sea to Summit Spark Pro 15 | 15F / -9C | 900+ | ~785 g | $649 |
| Western Mountaineering UltraLite | 20F / -7C | 850+ | ~820 g | $640 |
| Mountain Hardwear Phantom 0 | 0F / -18C | 800 | ~1200 g | $780 |
| Nemo Sonic 0 | 0F / -18C | 800 | ~1470 g | $600 |
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Sea to Summit Spark (45F)
The Spark is the bag I reach for when summer nights barely dip below 50F. At about 365 grams it is the lightest bag on this list, and the 850-plus fill power down packs down small enough to disappear into a corner of a frame bag. The 45F rating (around 7C) is honest, so do not expect it to rescue you when a cold front rolls through, but for July desert camps and warm valley nights it is all the bag you need. It is a true warm-weather bag, so be honest with yourself about the temperatures you actually ride in before you buy.
$349. Available at:
Kelty Cosmic Down 20
If you are new to bikepacking and choking on sleeping bag prices, start here. The Cosmic Down 20 uses 550 fill power down, a step below the premium bags, so it is heavier and bulkier (just over a kilo, and it eats more space in your bags than the lightweights). What you get for around $190 is a genuine 20F down bag that will carry you through three real seasons. It is the best warmth-per-dollar pick in the lineup if you can live with the weight.
$190. Available at:
Exped Terra 15
Exped is better known for its sleeping pads, but the Terra 15 is a quietly excellent value bag. It runs 650 fill power down in a roomy cut, rated to 15F (around -10C), and lands near $260, which undercuts most of the 15F competition by a wide margin. The tradeoff is weight: at about 1.25 kg it is one of the heavier bags here. Think of it as the value pick for riders who care more about budget and warmth than shaving grams.
$260. Available at:
REI Co-op Magma 30
REI's house-brand down bags punch well above their price, and the Magma 30 is the one I recommend most often. You get 850 fill power, a sub-600-gram weight, and a 30F rating for around $349, a combination that usually costs $100 more from the big brands. The catch is that it is REI exclusive, so there is no Amazon or MEC fallback. If you have an REI nearby or do not mind ordering direct, this is the smartest money on the page.
$349. Available at:
Nemo Disco Endless Promise 30
Side sleepers and anyone who hates the coffin feel of a mummy bag, the Disco is built for you. Nemo's spoon shape flares at the elbows and knees so you can bend and roll without fighting the bag. The 650 fill down and 30F rating make it a true three-season bag, and the Thermo Gill vents let you dump heat on warmer nights without unzipping. At about 950 grams it is not the lightest, but comfort is the whole point here. The Endless Promise version is also built to be fully recyclable, which is a nice bonus.
$280. Available at:
Therm-a-Rest Hyperion 20
When weight is the number that matters most, the Hyperion 20 is the answer. Therm-a-Rest packs 900 fill power down into a 567-gram bag rated to 20F, which is race-shelf territory. It is cut slim and trim to hit that weight, so it is less of a lounging bag and more of a precision tool for fast, light trips. At $470 it is not cheap, but the warmth-to-weight is genuinely excellent and it disappears into a frame bag.
$470. Available at:
Sea to Summit Spark Pro 15
The Spark Pro is the upgrade version of the bag that opened this list, and it is a serious piece of kit. The 900-plus fill power down is some of the best money can buy, the 15F rating handles cold shoulder-season nights, and it still packs small and weighs under 800 grams. At $649 it is firmly in the premium tier, but if you want one do-everything bag for spring through fall and you bikepack often, it earns the spend.
$649. Available at:
Western Mountaineering UltraLite
Western Mountaineering is the bag brand serious tourers whisper about, built by hand in California with no shortcuts. The UltraLite uses 850-plus fill down, weighs about 820 grams, and has the kind of even, draft-free loft you only get from a small shop that has been doing this for decades. It sits right alongside the small-shop ultralight builders whose gear outlasts the bike under it. At around $640 it is a buy-once bag, the one you hand down rather than replace.
$640. Available at:
Mountain Hardwear Phantom 0
When the forecast says single digits and you are still out riding, the Phantom 0 is the bag reviewers reach for first. Mountain Hardwear builds it around 800 fill power down with a 0F (about -18C) rating, and despite the deep-winter warmth it comes in right around 1.2 kg, which is light for a 0F bag. The shell sheds frost and spindrift well, and the cut leaves just enough room to wear a layer inside without crushing the down. Premium winter protection at $780.
$780. Available at:
Nemo Sonic 0
The Sonic is the winter bag for riders who run hot and cold in the same night. Its standout feature is the Thermo Gill vents across the chest, zippered openings that let you bleed off heat without breaking the temperature seal at your shoulders. The 800 fill down and 0F rating cover genuine winter, and at around $600 it is the value play against the boutique cold-weather bags. It is the heaviest bag here at roughly 1.5 kg, but that is the cost of staying warm at zero.
$600. Available at:
