Buying guide
Sleeping Bags Buying Guide (2027)
How to choose a sleeping bag in 2027: EN temperature ratings, down versus synthetic, fill power, shapes, and pads explained.
Temperature ratings: read the EN/ISO number
The EN/ISO lower-limit rating is the only temperature number you can compare across brands; it is the lowest temperature at which an average sleeper stays warm. Marketing names like 20-degree bags from different makers are meaningless without it. As a rule, buy a bag rated 10 to 15 degrees below the coldest night you expect, because cold sleepers, wind, and worn insulation all erode the margin.
Down vs synthetic
Down offers the best warmth-to-weight ratio and compressibility, and lasts a decade with care; 850-fill down like the Torchlight UL 20's is the premium tier, 550-fill like the Cosmic 20's the value tier. Synthetic insulation, like the Trestles Elite Eco 20's HL-ElixR Eco, keeps warming when wet, costs less, and tolerates rough treatment, but weighs more and packs larger. Your climate and care habits decide.
Shape: mummy, semi-rectangular, rectangular
Mummy bags are the most thermally efficient: the tapered cut eliminates dead air your body must heat, which is why every backpacking bag here is a mummy. Semi-rectangular bags add elbow room at a small warmth cost. Rectangular bags like the Celsius XXL maximize comfort for car camping where efficiency does not matter. Match the shape to your trip type, not your aspirations.
Do not forget the pad
A sleeping bag is only half the sleep system; the ground conducts heat away all night. Pad R-value should match your conditions: R-2 for summer, R-4 for three-season, R-5-plus for winter. A 15-degree bag on a summer pad will leave you cold at 30 degrees. Budget for the pad as part of the bag purchase.
Start with our top 3
The three highest-ranked products in our full sleeping bags ranking. Read the in-depth review where one exists, or jump to the product in the ranked list.
Big Agnes Torchlight UL 20
850-fill DownTek warmth with expandable panels that add room on demand.
- Temperature rating: 20°F (-7°C)
- Insulation: 850-fill-power DownTek water-repellent down
Marmot Trestles Elite Eco 20
The synthetic workhorse that stays warm even when damp.
- Temperature rating (EN lower limit): 20°F (-7°C)
- Insulation: HL-ElixR Eco synthetic
Kelty Cosmic 20
The budget down bag that made 550-fill famous.
- Temperature rating (EN lower limit): 20°F (-7°C)
- Insulation: 550-fill-power DriDown
Questions, answered
What is the most versatile sleeping bag rating?
20 degrees. It covers spring through fall, and unzipped it works for summer. The Cosmic 20 and Trestles Elite Eco 20 both hit this rating at very different prices.
How much should a good sleeping bag weigh?
For backpacking, under 3 pounds for a 20-degree bag; under 2 pounds is excellent. Car-camping bags can weigh whatever they want.
Are expensive sleeping bags worth it?
For backpackers, yes: the weight savings are real and permanent. For car campers, a budget bag like the Celsius XXL delivers more warmth per dollar.
How do I extend my bag's temperature range?
Add a liner (5 to 10 degrees), wear dry base layers and a hat to bed, and use a warmer pad. These three upgrades are cheaper than a second bag.