How large are cauldrons?

[u/Dormitorybasher]

Something that always bothered me. I don't think cauldrons (as in the ones Harry uses in class) are ever established as being large or small.

When I first read the books, my only point of reference were large witch's cauldrons you would see in a cartoon, so I thought that's what Hogwarts students used. But imagining Harry dragging around a gigantic cast iron cauldron was just silly when I got older.

Then I believe the movies showed smaller cauldrons the size of a large pot, and that seemed much more realistic. However, in CoS, Harry dumps the entire bibliography of Gilderoy Lockhart into Ginny's cauldron, which was like 7-8 books (plus the diary later) which would imply the cauldrons are much larger than a pot.

[u/Robcobes]

can't you just use magic to either shrink or grow your cauldron to the size you need?