Best sleeping bags

High fill-power down, well-made baffles and a small packed size. The sensible premium choice.

The reference three-season bag. High fill-power down gives the best warmth-to-packed-size ratio available, which is the criterion that matters most on this site, and REI publishes a standardized comfort rating rather than a marketing figure. The water-resistant down treatment helps with condensation and incidental damp but does not make the bag usable wet -- no down treatment does. The mummy cut is efficient and restrictive, which is the trade every warm lightweight bag makes.

Lower fill-power down at a fraction of premium prices. Bulkier packed, warm where it counts.

The value route into down, and a genuinely good one. Fill power measures how much space a given weight of down occupies, so lower fill power means you need more down -- and therefore more bulk and weight -- for the same warmth. That is the entire compromise here. For car camping and short trips where packed size matters less, it is the right trade, and the draft collar is a feature that cheaper bags skip and that makes a real difference to warmth at the neck.

Synthetic fill with a spoon shape that gives your knees room. Bulkier, and works wet.

Two genuinely useful ideas in one bag. The spoon shape widens the bag at the elbows and knees, which is the specific complaint side sleepers have about mummy bags, and the vents let you release heat without unzipping into a draft. Synthetic fill is the other half of its argument: it keeps insulating when damp, where wet down collapses and insulates almost not at all. The cost is packed size -- synthetic is significantly bulkier than down for the same warmth, and it loses loft permanently over years.

A quilt, not a bag: no back insulation, no zipper. Lightest warmth here, and drafty if used carelessly.

The logic behind a quilt is sound: the insulation under you in a sleeping bag is compressed flat by your body and does almost nothing, so removing it saves weight for no real warmth loss -- as long as your pad is doing the job. In exchange you get the lightest, smallest-packing warmth available. The honest catch is drafts. Without a zipper and a hood, a quilt needs its pad straps set up correctly and some technique, and most people have a cold first night or two while they learn it.

A 15F synthetic bag at a reasonable price. Heavy, bulky, and dependable in damp cold.

Cold-weather down bags are expensive, and this is the practical alternative. A 15F synthetic bag handles shoulder-season and genuinely cold nights at a price that makes it a reasonable purchase, and synthetic's indifference to damp is most valuable precisely in cold wet conditions where a soaked down bag becomes dangerous rather than just uncomfortable. The costs are packed size and weight, both substantial. It is a car camping and short-trip bag rather than a long-distance backpacking one.

A liner, not a bag. The cheapest way to add warmth and keep your bag clean.

On the list because it is the cheapest useful thing you can buy if you already own a bag. A liner adds some warmth -- less than manufacturers claim, but real -- and, more importantly, it keeps body oils out of the insulation, which is the main thing that degrades a sleeping bag over years. Washing a liner is easy; washing a down bag is a careful job you do rarely. It also doubles as a hot-weather sheet. Treat the warmth gain as a bonus rather than as a reason to buy a lighter bag.