When shopping for a down comforter, one of the most confusing aspects can be the fill, especially since there are three different terms used to describe exactly what is inside of one of these blankets: type, power and weight.

Most people instantly think that a higher fill power is better. Yes, it does provide more thermal insulation, but not everyone wants to be kept hot under their blanket.

Learn more about down fill below, and browse through our fill charts to help you decide on the right choice for your new comforter.

Fill Type
down featherThe actual material that is inside of a comforter is the fill type. For real down, this is often goose feathers. There are also alternative fills that are actually synthetic fibers designed to act like down but without many of the drawbacks. Some comforters even combine a mixture of real and synthetic materials.

Fill Power
The weight must be considered along with the fill power of a down comforter. This measurement tells you how many cubic inches are occupied by a single ounce of the down fill.

Since the weight is also measured in ounces and is referring to the same material, these two numbers together can give you a clear picture of what a blanket will really be like to use.

When the fill weight is the same, a higher fill power means more insulating capabilities (more heat retention) compared with lower number. However, if you have two products with the same power rating and different weights, the comforter with the lower weight will be nicer because it offers the same insulation but in a more lightweight product.

Generally, low weight and high fill powers can only be achieved by using special down feathers that are in large clusters. The larger the down cluster size, the more air it traps and the more loft it has (thus more heat retention abilities).

feathers-on-the-groundEider down feathers are considered to have the highest natural fill power in the world, making comforters using this product very expensive because this down of type is very scarce. However, average goose down offers fill powers of 550-600, which is often ideal for most consumers.

A higher rating often ends up being too hot to sleep with at night except for in very cold regions or environments. Higher fill powers are great for outdoor apparel like jackets, boots and sleeping bags, but mid level ratings are actually best for usage in bedding products.

Down Fill Power Chart
To give you an overall picture of what to expect from various fill powers, we have put together a chart below that should help you figure out what will work best for your intended usage and needs.

Fill Power Rating Description & Usage
Under 500 Anything under 500 is actually considered to be low-grade down and is generally not recommended for use in bedding products like comforters. These feathers often come from immature geese, ducks or other waterfowl.
500 Ratings 500 and above are great for down comforters and offer an ideal level of warmth for all year comfort. This is often goose down, synthetic alternative down fibers, or a mixture of both.
600 Higher quality down that has even larger clusters, more loft and great insulation with low weight. Great for lightweight comforters that still offer a lot of heat retention. This will typically be goose down and may even be from Hungarian white geese.
700 Luxury down comforters will often have a fill power rating of 700 or above. To avoid overheating, they are typically very light. The feathers will often be Hungarian white goose down and selected for their large, lofty clusters.
800+ Many people consider 800 to be the highest possible fill power, although others will claim that 1200 is possible. The highest rating for natural down is Eider, which has received ratings between 800 and 1200. There are also new technologies that claim to be able to increase the fill power of down, another reason why 1000+ numbers have been seen in recent years. Naturally, these are the rarest and most expensive of all down. Eider is often reserved for use in luxury goods and outdoor gear for extreme weather or climate usage. A comforter made from this type of material would likely be very uncomfortable to sleep under unless you happen to live in a cabin without heat in the woods in Alaska – even then, you might only want it during thr winter.

For more information on the fill weight of a comforter, see our lightweight down and summer usage guide.