WITHIN · FIELD GUIDE · Revised November 5, 2026

Down jackets: fill power explained, and how to wash one

The number on the hang tag measures loft, not warmth. Warmth is loft times how much down went in, and the wash is where most jackets lose it.

The number on the tag

Fill power	What it means
400 to 500	The low end of outdoor gear; bulkier for the same warmth
500 to 650	Warm and light enough for most conditions
650 to 800	Lighter and more packable for the same warmth
800 to 900	Very light or very cold weather gear

Fill power tells you how well each ounce lofts, not how much down is inside. A heavy parka at 600 fill can be far warmer than a thin jacket at 850, because it holds several times the down. Ask for the fill weight too, in grams or ounces, when you compare two jackets.

The tag reads the down when it was new and fresh from the wash. IDFL, the lab that tests down for the trade, says jackets can lose 10 to 40 percent of that loft in compression, shipping and storage. Wear, air and a tumble dry bring it back. A jacket that looks flat on a shop rail is not always a weak one.

How to wash a down jacket

Step	What to do
1. Read the label	Machine wash, hand wash or specialist clean. Follow it, especially on jackets with fur trims or leather patches
2. Prepare	Close the zips and snaps, empty the pockets, take off any fur ruff
3. Wash	Front loading machine, gentle cycle, cool or warm water, a soap made for down. No softener
4. Rinse twice	Leftover soap mats the clusters together
5. Dry	Low heat, with clean tennis or dryer balls, until no clumps are left. It can take hours
6. Finish	Shake it out and hang it to air before you store it

Top loading machines with a central agitator can tear baffles and twist the jacket. Never store down damp: it clumps, smells and can mildew.

Down or polyester fill

	Down	Polyester fill
Warmth for its weight	Higher	Lower
Packs down	Smaller	Bulkier
When wet	Loses nearly all its warmth	Keeps insulating
Lifespan	Up to three times longer, if cared for	Shorter

For wet cold, look for down under a waterproof shell. The Gore-Tex guide explains what the membrane adds.

Checks before you buy

Find both numbers: fill power and fill weight.
"Goose down" on a US label means at least 90 percent goose down.
Squeeze a baffle and let go. Good down springs back in seconds.
Check the shell's seams for feathers poking through. A few is normal; many means a loose weave.

Down jackets on within

Parkas and puffers at the boutiques today, with their prices. On 5 November 2026 Due West carried most of them.

Common questions

What does fill power mean?

The volume one ounce of down fills, in cubic inches, measured in a test cylinder under a small weight. 700 fill power means one ounce lofts to 700 cubic inches. Higher fill power insulates better for the same weight of down.

What fill power is good for a winter jacket?

Down rated 500 to 650 is warm and light enough for most conditions; 800 to 900 is used for very light or very cold weather gear. Warmth also depends on how much down is in the jacket, as well as its fill power.

Can you put a down jacket in the washing machine?

Yes, if the care label allows it: a front loading machine, a gentle cycle, cool or warm water and a soap made for down. Rinse twice so no soap is left in the clusters.

How do you dry a down jacket?

In a tumble dryer on low heat, until no clumps are left, which can take a few hours. Clean tennis or dryer balls break up the clumps. Down left damp clumps and can mildew.

Is down or polyester insulation better?

Down is warmer for its weight, packs smaller, and keeps its loft up to three times longer than most polyester fills if cared for. Wet down loses nearly all its warmth, while polyester fill keeps working damp.

What does goose down on a label mean?

In the United States, Federal Trade Commission rules say a product labelled goose down must hold at least 90 percent goose down. One labelled 100 percent down may hold only down.

Sources

Wikipedia, Down feather (fill power, ranges, US labelling), read 5 November 2026.
IDFL, Fill Power Questions and Answers, read 5 November 2026.
within's live shelves, read through the site's public search, read 5 November 2026.

Down jackets in stock now, to check against this guide

Canada Goose, Moose Knuckles and Mackage, from the boutiques on within.

More Canada Goose on within