Down jackets can be excellently warm and fit the bill just right for a number of outdoor activities, from hiking to skiing and everything in between. With goose down being the gold standard for warmth, that’s no surprise, though duck down and synthetic fills can also make quality jackets. Down jackets can be very versatile, and often last many years if taken good care of — which absolutely justifies the price of a quality down jacket.
If you’ve just started looking for the perfect down jacket, you may be wondering things like what a good fill weight is for a quality down jacket, what a down fill weight even means, and what other factors come into play to make a warm jacket.
What is down fill weight? Does fill weight determine quality?
Down fill weight is the measured physical weight or amount of down fill within a piece of gear. It is not the net weight of a down jacket, as that also includes other aspects of the jacket, like the fabric material and zipper components. The down fill is actually the lightest part of a jacket!
While the down fill weight is one of the parameters for measuring a down jacket, it’s important to know it’s not the only one that influences quality. Down fill weight is most important relative to one other term — the down fill power. Down fill power describes the quality and warmth of the fill, while the fill weight refers to the quantity of it in a jacket.
Down fill weight influences the overall performance of a down jacket, but its actual “quality” mostly comes down to the fill power — not the fill weight. Looking strickly from that lens, the highest quality down jackets will be those with the highest down fill power rating, generally anything above 800-fill. But as we just discussed, that doesn’t necessarily make it the warmest, and that’s where fill weight comes in with more importance.
What is down fill power?
Down fill power is a measurement of the quality of the down fill. The number itself refers to the loft of the fill — how much space a 1-ounce clump of down takes up, in cubic inches (e.g. 700 cubic inches of 1 ounce of fill would be 700-fill down). The loftier the down, the lighter, more compressible, and warmer — that is, the higher quality.
However, the warmth of a jacket depends on both the fill power and the fill weight. This of it like this: a jacket with 6 ounces of 700-fill down have twice as much insulation, and is twice as warm, like a jacket with 3 ounces of 700-fill down.
So, what’s a good fill weight for a quality down jacket?
When it comes to outdoor gear, quality can come in many tiers. For down and other jackets and clothing, gear often falls on a grading spectrum from ultra-lightweight summer clothing, to lightweight layerable pieces, to midweight jackets, to heavyweight cold-weather gear (NB: this is a measure less of the actual weight of the products, and more of the extent to which a jacket will keep you warm in increasingly cold temperatures).
You can find quality down jackets at any point on this spectrum, but the specs like fill weight and fill power will be different from one end to the other. Typically, heavier weight, warmer jackets will have both high fill weights and high fill powers. Within each tier, you’ll see a variance between fill weight and fill power.
The right balance of the two means that two jackets with opposite specs still fall into the same warmth category.
Note that to stay in relatively the same warmth category when shifting up or down a fill power rating, you’ll need to go down or up in fill weight, respectively. The same is true when shifting fill weights. Here’s the typical range of high-quality jackets:
Ultralight down jackets: Fill weight and fill power
Ultralight down jackets can have some of the best warmth-to-weight ratios and usually use high-quality down fill to maximize warmth. They typically range from 1.6 ounces of 1000-fill to 3 ounces of 800-fill.
Lightweight down jackets: Fill weight and fill power
Lightweight down jackets are fantastic in cool weather. They’re also a great option for layering and typically range from 3.5 ounces of 750-fill to 4+ ounces of 650-fill.
Midweight down jackets: Fill weight and fill power
Midweight down jackets are where the spectrum starts to trend into more winter or cold-weather gear (I’m looking at you, cold summer nights in the mountains). They’re sufficient for most three-season use, especially if you throw in layering. Midweight jackets typically range from around 5 ounces of 700-fill to 6 ounces of 800-fill.
Heavyweight down jackets (four-season): Fill weight and fill power.
Heavyweight down jackets is often the warmest jackets available, with the endearing nickname of “down puffy,” thanks to their being often lofty fill, and a lot of it. As they make up the end of the spectrum, there isn’t really a limit on fill weight here, but your typical quality four-season jackets will have at least 10 ounces of 700-fill, or 8 ounces of 800-fill, or more! So, the warmth you need in a down jacket depends on what you’re using it for.
The warmest down jackets will have both high fill power and high fill weight (meaning it has a high-quality down fill and a lot of it). This jacket would keep you warm in any weather — you could consider it “quality” even at the lightweight end of the spectrum. However, the opposite isn’t true a lightweight down jacket — even one with a high down fill power (e.g. 800-fill), will only keep you so warm if it has a low fill weight (e.g. 3 ounces).
This exact example of a jacket, commonly known as the “down sweater,” would be considered the highest quality lightweight, but wouldn’t cut it for a four-seasons coat.
Fill weight of a warm down jacket
Fill weight can greatly influence a down jacket’s warmth. A jacket with an 800-fill-power rating and a 3-ounce fill weight will still be very high quality, but only a lightweight rating for warmth, while a jacket with an 800-fill-power-rating and a 10-ounce fill weight would likely be one of the best (and lightest) four-season down jackets on the market. All that being said, you can find down jackets with equal or similar quality, with different specs and lower price tags.
The fill power rating, because it measures the quality of the down, has the biggest influence over price — so, if budget is holding you back from getting a jacket like the one described above, know that quality is a two-variable sliding spectrum here. You can balance a lower fill power rating with a higher fill weight to get a jacket that will keep you warm. Know that this type of balance can vary by the manufacturer — not just the lightweight vs. heavyweight classification.
Some manufacturers are specialized for extreme mountaineering and outdoor conditions and produce gear tailored to that customer — that is, someone looking for high-warmth, low weight. Other manufacturers are tailored to have more options for casual and everyday use.