I'm looking for a down jacket. They all seem to come with numbers but I'm not sure what they mean. For example :
- 90/10 Down
- Fill Power 700
What do they mean?
2 Answers
They are basically measures for the quality of the down fill.
The 90/10 part refers to the mixture of down and feathers. As down contains nearly no rigid structure, one adds some amount of feathers to give the whole filling some more stability. The example of 90/10 means 90% down, 10% feathers and seems to be quite a typical mixture. I'm not sure about the exact numbers, but mixtures worse than 80/20 or so would give significantly worse insulation.
The fill power, often with the unit cuin or cubic inch per ounce, defines, how good the downs regain their loft after compression. To test this, an ounce of the respective down is compressed in a cylinder for 24 hours. After release of the pressure the volume that the downs regained is measured in cubic inches. Good down for outdoor clothing typically has a fill power of at least 650 to 700 cuin, very good (but also very expensive) products reach fill powers up to 900.
answered Jan 14, 2015 at 13:18
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4@shimizu: There are EN ratings for sleeping bags, but as far as I know, there is no similar system for jackets. You could get a pretty good idea, though, by multiplying the fill power by the total weight. That would give you a measure of the jacket's volume.– user2169Commented Jan 14, 2015 at 17:58
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3@shimizu Usually Fill Power is listed along with Fill Weight (weight of the down itself), which will be less than the items total weight. Higher fill power can be equally warm for less fill weight.– AndrewCommented Jan 14, 2015 at 18:19
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1@shimizu The unit for "how much does a wearable item keep you warm" is called a clo. But I have never seen it listed, neither for down jackets nor for something else.– rumtschoCommented Jan 14, 2015 at 21:39
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1There's also a difference between the EU and the US in measurements standards, thus 800FP by the EU method is roughly equivalent to 850FP in the US.– requiemCommented Jan 15, 2015 at 5:56
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2@shimizu How clo relates to fill power and warmth really deserves its own question. (FYI, each 50 change in FP is about .1 clo.) In general, a quality (800FP) down sweater might have 100g, a down parka for extreme conditions might have 350g, and a down jacket you won't overheat in might have 250g of down. A 0C sleeping bag might have about 300g.– requiemCommented Jan 15, 2015 at 6:35
Your question is also addressed at http://www.outdoorgearlab.com/Down-Jacket-Reviews/buying-advice
High-end jackets often use lighter-weight fabrics and high-quality down. The only practical differences between them may be in features (hood? two-way zipper? water bottle pocket?) and exact fill weights. Lower-end models may use heavier, more durable fabrics and lower quality down[0].
The most effective means of objectively testing the jackets will require sending them to a lab for testing on a thermal manikin. Since you probably don't have that available, there are a few numbers you should look for.
- Fill weight (not power). This tells you how much actual insulation is present in the jacket, and has perhaps the greatest impact on warmth. Unfortunately this is not often posted (at least in the US).[1] If this number is not available, you can make a guess based on the amount of loft it has (i.e. how thick does it puff up).
- Total jacket weight. Obviously, since you're looking for the lightest and warmest, you also need to know how much the whole thing weighs. For this you may wish to bring a small scale to measure the actual weight. (Posted weights are often optimistic.)
- Fill power. Fill power is directly related to insulating value and the ratio of down to feathers. It is inversely related to weight (when comparing equal volumes). Extremely high fill values may be more vulnerable to humidity, but in general it is considered an indicator of quality (and certainly costs more). Higher fill power down also compresses smaller.
A final check is whether the jacket is "sewn-through" or "box-baffled"; the former allows for cold spots as there is no insulation at the seams. For a lightweight "sweater" this is of minimal impact, but if you're looking for something to use in serious cold you want baffled construction. Also keep in mind the temperature to which a jacket will be suited is very dependent on activity. Sitting around talking is quite different from snowshoeing, or even doing basic camp chores.
[0] E.g. duck instead of goose down, or lower fill power down.
[1] For fill weights I use the following rough examples, based on 800 fill power down: 75-125g: light down "sweater" 200-250g: mid-weight winter jacket 350g+: expedition-weight parka (Jackets using lower fill power down will likely need additional weight to provide the same amount of insulation)
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I actually found the answer here: m.outdoorgearlab.com/Down-Jacket-Reviews I'm still confused as to why the numbers don't really correlate to warmth though. Plus it looks like the idea that heavier it's generally warmer is incorrect, based on these reviews. It kind of just looks like I have to ask someone's opinion, which is pretty unscientific. Also, that price, while there is a correlation, does not mean quality.– jfaCommented Feb 5, 2015 at 1:24
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1@JFA Yep, assuming two identical jackets (same size, cut, and fabric) both with 100g of 700 fill down. If one has 100g of 800 fill down instead, it should be slightly warmer but still weigh the same. But, if one has 100g of 700 fill down and the other has (a wild guess) 180g of 600 fill down, the second would be heavier but still provide the same warmth. (And of course a jacket with a really burly outer fabric will weigh more without necessarily providing more warmth) So, multiple variables are in play that can offset each other.– requiemCommented Feb 5, 2015 at 6:20
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One item I left out is how densely the down is packed into the jacket; this can also have a small affect on its insulating value.– requiemCommented Feb 5, 2015 at 6:29