Even looking at the table for temperature vs density, I can’t reconcile the fact that 1 pint is 473 mL, and one pound is 454 g. Is the slightly-less-than 1g/mL really enough to cause such a difference?
(slow day at the office)
Because 1 pint is not 1 pound, contrary to the popular saying.
So not only is the pint not a pound except in the US it is not a pound in the US either. Another rule of thumb that is not helpful.
They should change the name from “fluid ounces” to “fluid approximately ounces”.
Actually, I’d say that in the US at least, it’s pretty much precisely what a rule of thumb should be – simple, easy to remember, and very close to being exactly right.
Maybe if they dropped “the world around” bit, which is flat out false.
Just go metric and move on with your lives 
Indeed. In Imperial “a pint of water weighs a pound and a quarter”
But…it doesn’t rhyme. 
It does in imperial pronunciation.
Grams measure mass and liters measure volume, so 1g/ml is only accurate for one density of water. I believe that’s water at 4C. Hotter or colder water would be less than 1g/ml.
Another reason the saying is “good enough” is that it is supposed to apply to dry stuff like sugar or flour, usually specified in pounds, and less dense than water. Also butter or lard, also less dense than water. It’s more nearly accurate for those, if you don’t have a scale.
I attempt no justification for “the world around” bit, however. That always struck me as stupid since people living less than 100 miles from me when I was growing up used a different “pint” and I knew it.
Word
So Alton was wrong?
Alton couldn’t pronounce plantain, astaxanthin, or arthropod correctly.
An imperial gallon is 160 (fluid) ounces. A US gallon is 128 fluid ounces. However, they are not even the same ounces…
Thanks to Wikipedia:
A real gallon of water is 10 pounds. Can’t get any simpler than that.
Oh no! I’ve been lied to! I had some free time doing some mind-numbing unit-dosing at work yesterday and no one there was able to help me. Thanks, SDMB!
How do you mispronounce arthropod?
Also, pronouncing plantain as it is spelled is not a mispronunciation, but a regionalism in the U.S. In fact, I have never heard it pronounce plan-tin in my entire life.
He said it “anthropod”, and I was raised in a time in which dictionary pronunciations were king. I have never seen a print dictionary with the “plan tane” pronunciation.
A pint of water
Weighs a pound and a quarter
In American pronunciation, “water” != “warter”. Though it’s closer than the rhymes you’ll find in a lot of poems and songs.