PHD jacket fill weights calculations

[J C]

I realised the other day while trying to compare down jackets that while PHD don't list fill weights for their jackets they do list the total weights with either (European rating) 800 or 900 fill-power down for medium-size jackets on their "design your own down jacket" mini-site. Using the relationship between fill-power values it is theoretically possible to calculate the fill weights of those jackets:

PHD Ladakh (-5C TOT, similar to Minimus): 108g of 800FP or 96g of 900FP
PHD Toubkal (-15C TOT, most similar to Yukon): 162g of 800FP or 144g of 900FP
PHD Svalbard (-25C, similar to Hispar): 207g of 800FP or 184g of 900FP
PHD Denali (-35C): 306g of 800FP or 272g of 900FP

Even keeping in mind that PHD use the European fillpower ratings, which means about 8% loftier than the equivalent US rating, these seem very low for the temperatures quoted.
The Toubkal/Yukon only gets around 162g of US850/860 down, whereas the comparable Rab Infinity (size L) gets 210g of US850. And the Svalbard/Hispar only has around 207g EU800 down for a -25C rating, which is very low compared to the 310g of EU800 in the Crux Lava (size M), and 271g (size M) of EU800 in the Valadre Immelman, both rated to -20C.

If you assume size M is roughly standard across these manufacturers (I believe it is), then I figure there are three ways to account for these discrepancies. 1) my maths is wrong, 2) PHD's site is not very precise, or 3) there is a vast difference between PHD's temp ratings and those of other manufacturers. I don't think my math is wrong since they make sense given the finished weight of the products given the weights of the materials and the construction methods they use. Since PHD's site lists very specific weights I can only assume that they are confident in their numbers, so I'm not sure what to make of their temperature claims.

I know PHD gear is used by athletes and professionals all over world, but I can't believe that PHD gear is somehow so well designed that they can use 50% less down than other manufacturers to achieve the same insulation levels. Therefore, I think PHD's "typical operating temperatures" shouldn't be used to directly compare with other brands like Crux and Valandre, it seems to be very much a "limit" rating rather than a "comfort" rating.

[Stephen M]

well spotted, at work now, will reply later as have a lot of experience with Phd kit.

[James holden]

i wouldnt be so confident in valandre's rating for bags anyways … they rating they "list" in the title on their site is not the en-LL rating, its more the extreme rating

for example they give the mirage as -17C … where then en-LL rating for it is -1C …

;)

[Anthony Weston]

I froze in a valandre mirage at about 25 degrees Farenheit , it was an uncomfortable night. (I sleep cold but it's rating is just wishful thinking)

I think a lot of companies get away with it because of layering, many backpackers
just add another layer and don't worry about it.

Now I test my gear just so I know what temperature I can take that sleeping bag down to with comfort.

[J C]

If Valandre are fudging their temp ratings that only makes me more suspicious of PHD's ratings.

Stephen: I'd love to hear more from you and others who own PHD gear. I was thinking about buying a Rondoy but now I'm not so sure it'll actually be suitable for the temps I'm facing.

[Stephen M]

Hi Jeremy,

PHDs temp rating for clothing are faily spot on, I have experince with the Yukon and Ultra and always found them warm.

I think the Rondoy is rated to -20c, the Hispar would then be the next step up.

I have also used 2 PHD bags in the past and they are very good.

Cheers,

Stephen

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