A sleeping bag that's too warm makes you sweat; one that's too cold is miserable at 3am. Getting the temperature rating right for your camping style is the most important decision — and the EN rating system makes it more objective than the old comfort-temperature guessing game.
EN (European Norm) and ISO tested sleeping bags have three certified temperatures: Comfort (the temperature a standard woman sleeps comfortably), Lower Limit (the temperature a standard man sleeps comfortably), and Extreme (survivability temperature — not comfortable). Choose your bag's Lower Limit temperature for the coldest night you'll camp. Women typically sleep colder and should use the Comfort rating.
Down fill: higher warmth-to-weight ratio, compresses smaller, lasts decades with care, useless when wet. Synthetic fill: works when wet, cheaper, less compressible, heavier for equivalent warmth. For backpacking in dry climates: down is the clear choice. For damp climates, kayak camping, or budget-conscious campers: synthetic. For car camping where weight and pack size don't matter: synthetic is fine.
Fill power (600, 700, 800, 900+) measures how much space one ounce of down occupies — higher is better. 800+ fill power down is premium quality: very light, very compressible, very warm. 600 fill power is adequate but a heavier, larger sleeping bag for the same warmth. Higher fill power bags cost more but pack smaller and last longer.
Mummy bags taper to follow the body shape — more thermally efficient but restrictive for sleepers who move around. Rectangular bags have room to shift positions — better for warm-weather camping and restless sleepers, worse for cold weather (dead air space at the feet cools you down). Semi-rectangular (barrel) bags split the difference.
A sleeping bag insulates from above but not from ground conduction — that's the sleeping pad's job. R-value measures pad insulation: R-2 for summer, R-4 for 3-season, R-6+ for winter. Most beginners buy a great sleeping bag and a cheap pad, then wonder why they're cold — the pad matters as much as the bag for cold-ground insulation.
Match your bag's Lower Limit temperature to the coldest night you'll camp. For summer camping above 40°F: a 40°F bag. For 3-season use (spring/fall with occasional freezing nights): a 20°F bag. For winter camping: 0°F or below. Always buy slightly colder than your expected conditions — it's easier to vent a bag that's too warm than to be comfortable in one that's too cold.
Wash in a front-loading machine (top-loaders with agitators damage down clusters) on gentle cycle with a down-specific soap (Nikwax Down Wash). Dry on low heat with two clean tennis balls to break up clumped down. This takes 3–4 hours. Allow to cool completely before storing. Store uncompressed in a large cotton storage sack — compressing down long-term damages the fill.
See also: Best Sleeping Bags for 2026 • Best Camping Tents • Best Sleeping Pads
