Compared

Cotton fill set against down and wool on three questions where they differ: warmth for the weight, a damp night, and washing at home. Each answer links to its source.

Is cotton or down warmer for its weight?

Down. At the same weight per area, a 2026 manikin study found down gave about 29% more insulation than cotton.

The study is reported in Building and Environment, 2026. It shows up in how comforters are sold. One 240 GSM cotton comforter sold for year-round use measures 90 by 92 inches at full/queen (Natural Linens), about 45 oz of cotton by our arithmetic. One seller's midweight down full/queen lists 35 oz (Parachute). The summer and year-round guide works through both.

Which fill handles a warm, damp night better?

Wool passes water vapor more readily than cotton or polyester, while cotton takes up sweat and conducts heat better once it is damp.

Both points come from a 2024 systematic review of fiber types and sleep (Journal of Sleep Research, 2024). It found only nine eligible studies. Its one duvet result favored goose down over cotton fill for deep sleep in a cool room, and most other trials tested sleepwear rather than comforters. Our cotton comforter guide sets out what that evidence can and cannot tell you.

Which is easiest to wash at home?

Cotton and down are often machine washable; the wool and alpaca inserts in one count of seller pages were spot clean only.

Whisper Organics lists its cotton-filled comforter as machine washable (Whisper Organics), and Puredown says to machine wash its down comforter cold on a gentle cycle (Puredown). Naturepedic lists its wool insert as spot clean only (Naturepedic). Cotton soaks up the most water of the three, so a queen or king needs a big drum: washers above 4.5 cubic feet fit a king-size comforter in Consumer Reports testing. See the washing guide.