# Thread: Loft / temp rating

1. ## Loft / temp rating

Found a nice chart the other day but can't find it . Have loft of down and temp range. Anybody point my in the right direction ? Thx

2. I had asked this question not to long ago and I was informed by a gracious member that western mountaineering uses this formula to determine degrees fahrenheit:

67 - 18 x loft

(p.e.m.d.a.s.)

It seems fairly accurate and I have no clue how folks figure these things out. But thankfully they do

3. I had this on file......
Shug

4. Thanks guys just what I was looking for shug . Waiting for the next report from sector 7 :-)

5. Originally Posted by Cool breeze
Thanks guys just what I was looking for shug . Waiting for the next report from sector 7 :-)
Whoooo Buddy.....in and out of Sector Seven with work so it may be a while for a forthcoming report.

6. Originally Posted by Shug
I had this on file......
Shug

So what does this translate into in terms of oz of down? IE, how many oz of down per inch of loft? And are we talking 800, 850, 900 fill?

7. Originally Posted by TheIrishmanHangeth
So what does this translate into in terms of oz of down? IE, how many oz of down per inch of loft? And are we talking 800, 850, 900 fill?
In order to calculate that, you need to figure out the volume of the chamber being filled, and the fill power of down being used.

Length x Width x Height / fill power

For example a chamber 50" long, 6" wide and a 2.5" baffle height with 550, 700 and 900 fill power:

50x6x2.5= 750 cu in

750 / 550 = 1.36 oz
750 / 700 = 1.07 oz
750 / 900 = .83 oz

You can also figure out an overstuff value by multiplying the oz by the % of overstuff desired. Using the 900 fill calculation from above and adding a 20% overstuff:

.83 oz x .2= .17 (rounded up from .166)
.83 oz + .17 oz = 1 oz per chamber.

There are a couple of fill calculators on HF that will do all the calculations for you if you enter the numbers into them - Catsplat and Meteor are 2 that come to mind. Great tools, especially when calculating radial/differential baffles.

And just to give proper credit, I believe Shugs chart originated from http://thru-hiker.com/projects/down_quilt.php

8. Originally Posted by vwgerald
Originally Posted by HappyHiker
In order to calculate that, you need to figure out the volume of the chamber being filled, and the fill power of down being used.

Length x Width x Height / fill power

For example a chamber 50" long, 6" wide and a 2.5" baffle height with 550, 700 and 900 fill power:

50x6x2.5= 750 cu in

750 / 550 = 1.36 oz
750 / 700 = 1.07 oz
750 / 900 = .83 oz

You can also figure out an overstuff value by multiplying the oz by the % of overstuff desired. Using the 900 fill calculation from above and adding a 20% overstuff:

.83 oz x .2= .17 (rounded up from .166)
.83 oz + .17 oz = 1 oz per chamber.

There are a couple of fill calculators on HF that will do all the calculations for you if you enter the numbers into them - Catsplat and Meteor are 2 that come to mind. Great tools, especially when calculating radial/differential baffles.

And just to give proper credit, I believe Shugs chart originated from http://thru-hiker.com/projects/down_quilt.php
Thanks folks!!

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