くらい ②To the extent that, So…that, About the only thing that...

くらい (often ぐらい in speech) expresses an approximate degree or extent. It's commonly used with number + counter expressions (the くらい① form), as in 100円くらい = 'about 100 yen.' It can also be used like ほど to express extent or degree, as in 足が動けなくなるくらい走った = 'I ran so much my legs couldn't move anymore.'

Both くらい and ほど can express extent in the sense of 'so much that (A)' or 'to the extent of (A)', and are often interchangeable, e.g. 驚くくらい静かだった / 驚くほど静かだった ('It was quiet to a surprising degree.') くらい (also written as ぐらい) tends to sound slightly more colloquial, and each word has other uses where they may not be interchangeable.

Both まで and ほど share the core meaning of 'to the extent of,' but are used differently. まで emphasizes inclusivity or a surprising limit, e.g. 骨まで食べた ('He even ate the bones.'). In contrast, くらい② means 'to the point of' and often expresses degree, e.g. 叫びたいくらい怖かった ('It was so scary I wanted to scream.').