NEMO Disco 15 ranks first among these sleeping bags, and REI Co-op Magma 15 ranks second. All five contenders were evaluated on the same published criteria, and their weighted scores determine the order from highest to lowest.
Best overall
NEMO Disco 15 is a down backpacking bag with the brand's roomy Spoon shape, which gives side sleepers more space at the knees and elbows. Thermo Gill vents broaden its usable temperature range, but the extra room adds more weight and packed volume than a trim mummy bag.Strongest alternative
REI Co-op Magma 15 is a lightweight 850-fill down mummy bag offered in multiple length and width combinations. Its warmth-to-weight ratio and fit choices make it a strong backpacking option, though the narrower shape feels less relaxed than the NEMO for active side sleepers.Best balanced contender
Kelty Cosmic Down 20 is an approachable three-season down bag that balances real backpacking capability with a substantially lower price than premium ultralight models. It is comfortable and easy to recommend to occasional campers, but its lower-fill-power insulation makes it heavier and bulkier for the warmth.Best specialist contender
Big Agnes Sidewinder is shaped specifically for side sleepers, with body-mapped insulation and construction intended to keep the hood and zipper aligned as the user turns. The specialized fit improves comfort for its target sleeper, while being less universally roomy and efficient than the top all-around bags.Best situational contender
The North Face One Bag uses removable insulation layers to create several temperature configurations in one modular system. That versatility suits campers moving between seasons, but the layered design is heavier and more complex than carrying a single backpacking bag matched to the forecast.Three independent write-ins unlock an honorable mention. The 10 strongest active mentions are shown; inactive mentions archive after 12 months. At 25 monthly votes, a contender enters a scoring review for possible top-five promotion.
No honorable mentions yet. Repeated write-ins merge automatically.
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The five criteria create the AI baseline. The community adjustment is then added or subtracted to produce the current published score.
| Criterion | #1NEMO Disco 15 | #2REI Co-op Magma 15 | #3Kelty Cosmic Down 20 | #4Big Agnes Sidewinder | #5The North Face One Bag |
|---|---|---|---|---|---|
| 95 | 95 | 94 | 88 | 88 | |
| 91 | 88 | 85 | 88 | 87 | |
| 92 | 92 | 88 | 91 | 82 | |
| 97 | 94 | 92 | 86 | 87 | |
| 96 | 88 | 91 | 88 | 86 | |
| AI baseline scoreWeighted criteria result | 94.0 | 91.8 | 90.3 | 88.3 | 86.2 |
| Community adjustmentVote-share influence | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Current published scoreBaseline + community | 94 | 92 | 90 | 88 | 86 |
Select any two contenders above.
We’ll line up what matters.
15°F
15°F
650-fill RDS down
850-fill water-resistant down
Classic Spoon
Mummy
Backpacking · side sleepers
Lightweight backpacking
Thermo Gill vents
Nine fit options
SummaRank compared field testing, fit and comfort guidance, durability, safety context, and value across realistic use cases, using current material from Outside, REI Co-op, Runner's World and the linked official or research references. Each contender was scored independently on the same five-part scorecard: Performance 30%, Comfort 20%, Durability 20%, Versatility 15%, Value 15%. The weighted total determines the published order from highest to lowest; criterion strengths are not assigned by rank position, and verified community voting can make a limited, visible adjustment.
The five criteria create the AI baseline. The community adjustment is then added or subtracted to produce the current published score.
| Criterion | #1NEMO Disco 15 | #2REI Co-op Magma 15 | #3Kelty Cosmic Down 20 | #4Big Agnes Sidewinder | #5The North Face One Bag |
|---|---|---|---|---|---|
| 95 | 95 | 94 | 88 | 88 | |
| 91 | 88 | 85 | 88 | 87 | |
| 92 | 92 | 88 | 91 | 82 | |
| 97 | 94 | 92 | 86 | 87 | |
| 96 | 88 | 91 | 88 | 86 | |
| AI baseline scoreWeighted criteria result | 94.0 | 91.8 | 90.3 | 88.3 | 86.2 |
| Community adjustmentVote-share influence | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Current published scoreBaseline + community | 94 | 92 | 90 | 88 | 86 |