Does anyone know why 4 cu. ft. of Perlite is considered 103 (or thereabouts) quarts of material by some sellers, while others go with the “straight” conversion of 4 cu. ft. to 120 quarts? I see the 4 cu. ft. = 103 quarts stated for vermiculite, from some sellers, as well.
Kind of like cooler sizing game. The only coolers that should be in liquid measurement are the orange 5 gallon water dispensing coolers but they use quarts even for big chest style coolers even though no one fills them with liquid. Then the small coolers are sized by how many cans they'll hold which is at least based on reality to a degree, even if some people drink bottles or put food in them.
I guess one exception for the extra large chest coolers is that sometimes they end up with freshly caught fish in them and the fish is held in water. 96 quarts of fish?
CU FT or lbs for granules. Everything else is meant to confuse. I guess maybe they figure people can visualize the size of a quart container.
Viagrow goes all out(insert Viagra joke here) with cu ft, liter, qt, gal, kg and lbs
Meanwhile, Elliot Coleman uses parts or volume; 3 buckets of this, 1 bucket of that etc for his soil block mix. Mother Earth News' soil block recipe uses cups but since the ingredients are not liquid, it's also a volume or parts measurement. In either case, any sized container will do. Same as using a scoop, 3 scoops of this, 2 scoops of that.
That begs the question, if 1 cu ft of brand A weighs more than 1 cu ft of brand B, is one more or less effective at soaking up and releasing water?
The above Viagrow perlite is chunky but they also sell one that's not chunky. Same volume, different weight. Normally bigger chunks means more air space between them which means a given volume should be lighter. A bucket of rocks should be lighter than a bucket of sand that originated from the same rock. Viagrow is the opposite so the chunky is more dense - mass. Their descriptions give no explanation as to the weight difference for the same volumes. Might be something to do with the processing. One was heated and popped more. Could also be a different source material. Darker color = more dense?

Well that was not a very helpful random brand/example I stumbled on. Glad I could be of help. LOL
The quart is based on the gallon, the definition of which has changed throughout history based on the commodity being referenced. The current definition of the US quart is based on the English wine gallon.
And here I thought it was based on water. Silly me. Why worry about the life giving substance of water when we can get drunk?
All the online conversion tools say 4 cu ft = 19.68831 qts.(119.68831169 on another site)
So I guess I would stay away from the 103 quart people or just ignore quarts and go for the best cu ft price. Looks like on homedepot, the smaller bags are in qts while the larger bags are in cu ft, even in the same brand. Meanwhile garden soil and compost in bags are generally sold by the cu ft so it makes sense for perlite to be the same since all your soil mix recipes are by volume, parts or buckets as it were but still a volume. Shop around and use the calculators to convert from qt to cu ft or visa versa for brands or bag sizes that only list one.
cu ft to qt -- https://www.unitconverters.net/volume/cubic-foot-to-quart-us.htm
qt to cu ft -- https://www.unitconverters.net/volume/quart-us-to-cubic-foot.htm
I even see Dry Qts. Is that like 1/4 gallon of a dry English wine? Crazy. Just some modern made up thing that's wrong and meant to confuse imho. Might as well sell it by the Pollard Scoop. (.47592846291 cu ft)
Just noticed how much later sunrise is. Days aren't exactly short yet though at 13:56 long. Create a 1 year day length chart for your location - https://aa.usno.navy.mil/data/Dur_OneYear
Nov 19th through Jan 22nd are my days of 10 hours or less day length. Right at two months.