Under Quilt Vs. Top Quilt Loft for Warmth Rating

[OrangeBanana]

Does anyone know if there are different loft values for temp ratings for under quilts? I know that ~2.5 in. is around a 20* rating for top quilts and sleeping bags, but I saw an enlightened equipment under quilt that was thinner and still had a similar warmth rating. I'm making the quilts for my hammock right now, and any down savings would be extremely helpful for my wallet. Thanks!

[ScooterInVegas]

I used this and then added 20%.

Remember the fill power rating for down is in "perfect" conditions. That is way I added the extra 20%.

http://www.dream-hammock.com/DownFillCalculator.html

[Just Bill]

I still use the Backpacking Light Chart- though Zpacks is the safest place for it- http://www.zpacks.com/quilts/down_loft.shtml

Yes... UQ does need more loft in my opinion. Guessing many folks agree but the Hammock vendors tend not to be as cut and dry as EE is on showing it.

Long story short-
Bump up one category (10*) on the BPL chart for the UQ.

So you want a 20* TQ- 2.2" baffles.
You want a matching UQ- 2.6" baffles.

PS- Tim (EE) uses the BPL chart too. The hammock vendors tend to use a slightly more conservative chart in my experience.

For MYOG... unless you are slitting your own baffle material...

2.5" baffle material for the TQ (2" finished) and 3.5" baffle material for the UQ (3" finished) makes a good 20* combo.

[OrangeBanana]

Thanks for the help guys. I was planning on doing 2.5" baffles with a 20% overfill, so maybe I'll drop the TQ down to 2.2 and add the extra down to the UQ.