Can you compare warmth of different down jackets?

Clearly having too much time on my hands, I found myself wondering if there’s an “objective” way to compare down-filled jackets. There’s no EN rating similar to that used for sleeping bags; I’m not sure you can have sufficient testing controls to do that with jackets since the full body isn’t encased.

I did wonder if multiplying fill factor times amount of fill might be a rough guideline as to which was warmer for garments of similar design. For example, if you were looking at two waist-length hooded jackets with full-length zippers, elastic cuffs, adjustable hood, and drawcord or elastic waist, how would you know whether the one with 12 ounces of 700-fill down is warmer or colder than the one with 9 ounces of 900-fill down.

One thing that came to mind is multiplying quantity of down times fill power to estimate the insulating value of each. In the example above, the 700-fill jacket would have a “factor” of 8400 (12x700) while the 900-fill jacket would have a “factor” of 8100 (9x900) - and the rough estimate would indicate that the 700-fill jacket might be marginally warmer.

I realize that there are a lot of qualitative factors that can affect warmth (how well each shell blocks wind, whether the “cut” of the jacket allows the down to fully loft, etc.)

Any thoughts on a rough-and-ready method to estimate this? If there is, it would certainly make it easier to compare garments when you can’t try them on, such as when you’re looking at a website or catalogue (remember those?)

I find dow jackets to largley be an absolute rip off. If you soend the same ammount on a sleeping bag you get box walls, off set seams, etc. With most jackets you get stitch through construction and are asked to pay big money. I would look at this for warmth comparison glenn

Assuming all other things being equal, which is a big and probably unrealistic assumption, your "fill factor" might have some use. It also assumes the down tubes are stuffed to the same degree of fullness.

Loft is still the determining factor between similar jackets, but if you can't see them in person, the "fill factor" might be an additional parameter to consider.

I miss catalogs.

I think that would be a very hard real world comparison. Mainly because variances in how hot people get, how sweaty they get, how well they evaporate moisture, calorie intake, exactly layering and wicking used.

I have thought about this in far too much length. Obviously down rating and down fill can be compared but then the cut of the jacket comes into play. What do the baffles look like? Even the fabric comes into play - will you loose heat via convection?

Some manufacturers do post an expected comfort range. I have no idea if they are performing EN testing (can you?).

I have a few down jackets. My Ghost Whisperer is sometimes warm at say 10C and sometimes it is cold. To an earlier point, sometimes I am tired and less well fed and the jacket doesn't keep me warm.