{"id":3051,"date":"2018-01-08T16:42:44","date_gmt":"2018-01-08T15:42:44","guid":{"rendered":"https:\/\/superligero.es\/?p=3051"},"modified":"2026-03-09T18:06:06","modified_gmt":"2026-03-09T16:06:06","slug":"what-does-fill-power-900-cuin-mean","status":"publish","type":"post","link":"https:\/\/superligero.es\/en\/blog\/what-does-fill-power-900-cuin-mean\/","title":{"rendered":"Down Quality: What Fill Power and CUIN Mean"},"content":{"rendered":"

\"que<\/p>\n

Some of the products we sell at SuperLigero.es<\/a> are filled with natural goose down up to 900 cuin<\/strong>.<\/p>\n

But\u2026 what does Fill Power 900 cuin<\/strong> actually mean?<\/p>\n

I asked myself the same thing when I started buying my first down clothing for the mountains.<\/p>\n

In this article I want to explain, in a simple way, what Fill Power means, how it\u2019s measured, and why it matters so much when you\u2019re choosing a jacket or a sleeping bag.<\/p>\n

Air is the real insulator<\/h2>\n

To understand how down works, you first need to understand how thermal insulation works.<\/p>\n

Air is fundamental.<\/p>\n

Heat is transferred when there is air movement. That\u2019s why we use a wind jacket: to stop cold air from getting in and carrying away our body heat.<\/p>\n

This phenomenon is called convection<\/a>.<\/p>\n

Insulating materials work by trapping air inside them.<\/p>\n

The more air they can hold, the better their insulating performance.<\/p>\n

That\u2019s why fibrous or porous materials, like down, are excellent thermal insulators.<\/p>\n

Feathers vs down<\/h2>\n

Not all feathers are the same.<\/p>\n

Many manufacturers use a mix of feathers and down<\/strong> in their products.<\/p>\n

But there\u2019s an important difference between the two.<\/p>\n

Down<\/strong> is the part that actually provides insulation.<\/p>\n

It\u2019s a very light, three-dimensional structure that traps large amounts of air.<\/p>\n

Traditional feathers have a stiff central shaft and provide much less insulation.<\/p>\n

That\u2019s why a garment with:<\/p>\n

90% down \/ 10% feathers<\/strong><\/p>\n

is not the same as a garment with:<\/p>\n

60% down \/ 40% feathers<\/strong><\/p>\n

The higher the percentage of down, the higher the insulation quality tends to be.<\/p>\n

What Fill Power (CUIN) means<\/h2>\n

The Fill Power<\/strong> measures down\u2019s loft.<\/p>\n

In other words, how much volume a given amount of down can occupy.<\/p>\n

This is expressed in CUIN (cubic inches per ounce)<\/strong>.<\/p>\n

The higher the CUIN number, the more the down can loft and trap air.<\/p>\n

This means:<\/p>\n

    \n
  • Better insulation<\/li>\n
  • Lighter weight<\/li>\n
  • Better compressibility<\/li>\n<\/ul>\n

    For example:<\/p>\n

      \n
    • 650 cuin down \u2192 mid-range quality<\/li>\n
    • 800 cuin down \u2192 high quality<\/li>\n
    • 900+ cuin down \u2192 premium quality<\/li>\n<\/ul>\n

      Some specialist manufacturers even use 1000 cuin<\/strong> down in highly technical garments.<\/p>\n