They hold about two day's worth of liquid for a couple; that is, around four servings of milk, juice, etc...
But what about the smaller two-serving size? Because there's less wiggle room in a smaller pakage, these cartons are a little more generous at 600 ml, rather than half a litre. In the USA, they're not a pint, but rather 20 fluid ounces, or 20/32nds of a quart.
I wouldn't dream of ordering anything other than a pint in a British pub, which the pub police have decided equals half a litre. (They've given me a sip or two bonus, you'll notice). I ask the waitress for a cup of coffee, not 200 ml. And even here in highly metricated Germany, I order a Mass of beer rather than a litre.
I find it interesting that the imperial system is based on the measurements of a human body or some king's body and the metric is all based on an earth measurement. It would follow that measurements that deal with the human body and it's needs would be better described by imperial measurements. The day's need of liquid. The length of one's foot. How much beer you can drink in Germany. It is probably the reason why body based measurements are loved and still in use - because they work. They accurately describe things associated with the needs of the human body.
Interesting enough there are other measurement standards that have pertained to architectural building throughout the world based on body measurements. In Japan the old houses were proportioned and built according to the module and dimensions of a tatami mat called 'Ken'. (roughly 3'x6'). This is derived from the space required by a sleeping person. One half Ken is the space required for a sitting body (3'x3'). The room sizes were decribed in how many tatami mats made up the room. Hence a 4 tatami mat tea room, a 6 tatami mat room. This is how all houses were planned which ensured that they would have proper dimensions to fit a human body.
A more modern measurement system derived from human proportions was Le Corbusier's Modulor. He used this measurement system to size furniture and architectural dimensions to ensure all of his interior spaces were comfortable for human inhabitation. (Not sure this worked in the real world, nice theory though) A standing figure was the dimension loosely based on daVinci's Vitruvian Man, where the ideal height of a man is 8 figure heads tall. He broke down measurements of the human body in different states of rest and poses. Other measurement systems based on nature include the Fibonacci Sequence (think nautilus shell) and the related Golden Ratio which the Ancient Greeks developed to size and proportion their temples. The Golden Ratio is still used by Architects to design facades.
In helped that in 1966, the easiest and most useful "metrication" occurred. Australia switched from a base 12 currency (pounds, shillings, pence, soverigns, florins, and whatnot) to a base 10 currency (dollars and cents).
Interesting Headbang, I never knew there was such a thing as a base 12 currency in modern times. This makes sense because 12 is a magic number of sorts. Eggs still come in a dozen because as a base you can divide them with the greatest number of people, 1, 2, 3, 4, 6, 12, hence bartering becomes easier. If you are dealing with gold pieces as currency this base 12 system would make sense. 12 months out of the year too. Coincidence?
And the size of a 2 x 4 was standardised at 50 mm x 100 mm--you may not realise this, but a so-called 2 x 4 measures substantially less than 2 inches by 4 inches, and it has varied from time to time and place to place. I have heard some Australians refer to this woodcut as a "metric two-by-four", curiously.
A 2x4 is really 2"x4" in board feet. That is the measurement of wood before it gets cut. We still calculate wood quanities like this because it is easier to quantify how much lumber a log or block of wood really holds. A nominal sized 2x4 in the US is actually 1 1/2"x 3 1/2" because the saw blade thickness.
So listen up, America. The metric system makes more sense, and it ain't so hard to change. All it takes is an enlightened bureaucracy to work out the details beforehand, a positive attitude to progress, and a little goodwill.
(So I guess it's out of the question.)
That's sad, because the sheer size of the US market sometimes drags the rest of the world along with it.
It would be a lot easier to work with the metric system. I agree with Gillette and everyone here. It is just the coordination that is a bit tricky for the switch.
Again, sorry for the long post.
I actually miss your long posts Headbang.