Which is really cool.
Here is a neat graphic to flesh it out some.
Here we see that two cups make a pint, two pints make a quart and four quarts make a gallon.
Ergo promptus, ipso facto: one cup weights 1/2 lb, a pint weights one lb, a quart weighs 2 lbs and a gallon weighs 8 lbs.
Lesson: if you have a lb of water, you have a pint. You also have the volume of two cups and half the volume of a quart and 1/8 the volume of a gallon–so, given one pound of water, you can create containers of standard measure.
That is cool.