Determining the quality and potential warmth of a given comforter is quite simple when you’re working with down. That’s because of the standardized measurement known as fill power. In a nutshell, fill power refers to down material’s ability to insulate a sleeper. To obtain this measurement, one must compress the down and observe as it fluffs up once released. Down with greater fill power will fluff up all the more.

In the case of a down alternative comforter, it’s important to look at the thread count of the material and the type of fill used. The most comfortable, highly insulated filling will approximate down in nearly every way with the notable exception that it’s made of fiber. Any thread count greater than 200 will mix resilient strength with surprising softness. Don’t forget to factor in breathability as certain comforters can be stifling.