How fast can't kidney stones grow? it's for a school assignment and i'm having trouble finding information.

Here's your answer: The vast majority of kidney stones certainly grow very slowly, as we commonly see them as incidental findings at autopsy and they have surely been growing for many years. This being said, a proteus infection in the kidney or a hyperuricemic crisis during an illness can precipitate struvite or uric acid solids in the kidney which could easily form a stone in short order.