It’s always been very obvious to me, why using total fill weight, spread into an unknown area, can’t be an effective comparison metric. Over the years, there have been hundreds of examples of people being led astray by it, and this continually backs up my position on it. However, to anyone who isn’t constantly exposed to it, they’re basically just taking my word for it, based on a sound theory, or they’re hearing an anecdote. I’ve never felt it was worth my time to compile specific data on it because I’ve always just viewed it as a violation of what I call scientific analysis. Compiling data for something with undefined variables always felt pointless. I guess the point is to define the variability in the undefined parameter. Anyway, recently there was some reason that motivated me to run some specific numbers on it. Here is what I came up with.
I took the “standard” or “regular” sizes of five different common quilt manufacturers and actually calculated the amount of area each has, to the best of my abilities with what info I have. The way each system tapers makes quite a big difference towards the amount of area it has, and this info is not made available. I had to rely on some physical measurements, extrapolation based on the dimensions that are made available, photos, and my knowledge of how they typically would taper. Across Hammock Gear, Enlightened Equipment, Zpacks, Hyperlite, and Katabatic, I found an 11 -12% difference between the insulated areas of these. The largest of them, having 11 – 12% more area than the smallest. This means that, even if someone is being very diligent to make sure they are only comparing “like” items with similar features and dimensions, the margin of error is still 11 – 12%. A quilt with 12oz of total fill could be the exact same warmth as one with 13.5oz, but you don’t know what the margin actually is.
HG Bur – 3840 sqr in
EE – 3679
Z – 4074
HL – 3884
Kat – 3655
The first four use a mid point taper, which is basic with little attention to efficiency. These typically have a bunch of extra space and weight that isn’t needed. The EE comes in with a lower area, even with the basic cut, because it is narrow and short. The Katabatic comes in low with similar dimensions as the EE, but also includes an efficient, fitted taper. The Zpacks and HL are just massive, likely combating poor draft control systems with girth. The HG landed in between with similar widths to the EE, but in a longer length.
I’m 5′ 10″ 140lbs and these are the recommended sizes for me. For reference, when I build my own system with an intricate and efficient cut, my system area is 3197. In the context of a custom sized system vs an off the shelf basic, total fill weight has a 27% margin of error. Worse than that, is that this encourages weight creep. The “warmth” looks pretty good on the spec sheet for a system with a ton of extra area. There isn’t much incentive to be efficient with sizing because the consumer perception thinks cold. Reality is, due to efficient sizing, reduce surface area, and reduced internal volume, the one with 3197 can comfortably take me 10 degrees lower than one with 4000, with less fill.