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Down fill power

Down fill power

Postby doggy » Mon Mar 28, 2016 10:35 pm

I'm not getting this whole fill power thing.
I'll give you an example, force ten used to do three altitude bags called 650, 750 and 1000. They all had the same fill power of 650. How does that work ?
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Re: Down fill power

Postby tenohfive » Mon Mar 28, 2016 11:05 pm

I would hazard just more of it?

Fill power=how effective the down is. Bigger number means more effective down.
Fill amount=how much down there is. As with synthetics, the more insulation the warmer it'll be.

So if you've got 300g of 650FP down in one jacket and 400g of 650FP down in another, the latter will be warmer. But also (all else being equal) 100g heavier.

Where it gets confusing for me is chucking in variables in both factors - 300g of 650FP vs 150g of 850FP for example. But suffice to say that the higher the fill power number (650, 700, 800 etc) the warmer it'll be, and as such you can have less of a high FP down and still get the same (or more) warmth than a greater weight of lower FP down.
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Re: Down fill power

Postby teaandpies » Mon Mar 28, 2016 11:58 pm

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Re: Down fill power

Postby TheFox » Fri Apr 01, 2016 3:05 pm

Fill power relates to how much volume the same amount of down takes up, e.g. 100g of 500 CUIN will take up about half the space that 100g of 1000 CUIN will take up. Larger numbers are better, because the more the down expands, the more air it traps, thus the warmer it is.

So with a larger fill power but the same amount of down, you get a garment that weighs the same as one with lower fill power, but is warmer. Alternatively, with a larger fill power you can reduce the amount of down until at a certain point both garments are equally warm, but the one with the larger fill power will be lighter and more compressible, which is a plus as it takes up less space in your backpack.

With down jackets made for hiking and mountaineering you want something that is warm enough to keep you cozy on breaks and in emergencies, but light enough to spend most of the time in the backpack, because even in winter you will generate a lot of heat while walking up slopes, and will not want to wear a down jacket while on the move.

So you would want a jacket that has high fill power, probably at least 700 CUIN. High quality models usually have between 750 and 900 or so, with the best ones available on the market having 1000. And because fill power alone doesn't tell you how warm your jacket will be in absolute terms, because that depends on the total weight of the down and the fill power, you need to check out jackets for yourselves, or read a number of reviews to get an idea what would suit you.
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