Know Your Down Jacket

What is a Down Jacket?

A down jacket is a jacket which has been insulated with the soft feathers from duck or geese. Down is a very good insulator as the fluffiness of down creates thousands of tiny air pockets which trap warm air and retain heat, thus helping to keep the wearer very warm in cold winter weather.

The down (filler) will be either goose down, duck down or a combination of the both.   Companies often mix down with typical feathers to reduce costs. Down is easy to compress and pack, which has made it very popular for jacket insulation for decades.

Benefit of Down Jacket

  • Excellent heat retention:- Down is incredibly lofty, with millions of tiny air pockets that keep warmth trapped inside.
  • Lightweight. The weight of the down used in a jacket is very less. It can make a down jacket half the weight of comparably warm jacket made of other materials.
  • Packability: The volume that makes down warm and cozy also makes it compressible, you can pack it into half the space of a typical fleece jacket.


Loses insulating ability when wet and takes a long time to dry out
Expensive compared to other materials

Down Fill Power

Fill power is a measure of the loft or “fluffiness” of a down product that is loosely related to the insulating value of the down. The higher the fill power, the more air a certain weight of the down can trap, and thus the more insulating ability the down will have.

Down Jacket Fill Power Ratings

Fill PowerRating
400 – 450Medium
500 – 550Good
550 – 750Very Good
750 – 900Excellent

Fill power is measured in cubic inches per ounce. To test fill power an ounce of down is compressed by weight in a glass cylinder. the ability to bounce back and ‘loft’ is calculated as the fill power.

Fill power is also an indication of the quality of the down used. The better the quality of down the higher the fill power. Fill power ranges from 400 to 900. For down, outerwear ratings will generally fall between 600 and 800.

Generally, higher is better, but it doesn’t necessarily mean a jacket with a higher fill power will be warmer. A 900-fill-power down jacket that has only 30g of down fill won’t be warmer than a 450-fill-power jacket with 100g of down fill. In theory, 50g of 900-fill-power down would be the same warmth as 100g of 450-fill-power down but the 900 fill power jacket would probably be lighter and more packable.

Good fill power?

Down fills are typically rated on a scale from 550 to 800+, with 650 to 750 being high quality and 800 and higher is the best. Most down jackets are somewhere around 400 to 600, but premium brands, such as those you’d find in a camping store, are typically around 800.

Prakash Dutt

Prakash is an accomplished apparel professional with extensive experience in apparel manufacturing, sourcing, quality control, sustainability, and CSR.He is a lean management professional (black belt in lean six sigma), innovative and open to experimenting with new technology and changes in the industry.

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