Often, the 名詞（めいし） (noun) くらい is used as a 副助詞（ふくじょし） (adverbial particle). This use of くらい (or ぐらい) expresses the limit of something, in a similar way to ほど. This means that it can be translated as ‘about (A)’, ‘so (A) that (B)’, or ‘(A) to the extent of (B)’. Let’s take a look at a few examples.

• 今日（きょう）はもう一生（いっしょう）走（はし）りたくないくらい走（はし）った。
  Today, I ran so much that I don't want to run again in my whole life.
• わたしも叫（さけ）びたいくらい、怖（こわ）かった。
  I was so scared that I wanted to scream too.
• 5連休（れんきゅう）が必要（ひつよう）なぐらい疲（つか）れています。
  I am tired to the extent that it is necessary for me to have 5 days off.
• 俺（おれ）もキヨミさんくらいピアノが弾（ひ）けるようになりたい。
  I want to be able to play the piano about the level of Kiyomi-san.

Despite translating in the above ways, we can see that this use of くらい is similar to the standard kanji use 位（くらい）, which literally means a ‘rank’, or ‘grade’ of something. What this means is that (A) will usually be considered to be at the ‘grade’ of something that was required in order to cause/allow (B).