〜くらい／ぐらい
To the point that, about, at leastmachine translation
FormationVerb plain form／noun + くらい／ぐらい
You've been using くらい・ぐらい since N5 to estimate numbers (三十分ぐらい — about thirty minutes). At N3, it gains an additional DEGREE meaning: "to the point that" — 歩けないくらい足が痛い (my leg hurts so much I can't walk). This use runs parallel to affirmative ほど, and in many sentences the two are interchangeable.
くらい's second distinctive nuance is BELITTLING: treating what's mentioned as a small matter, a bare minimum — "at least, just": 自分の部屋ぐらい自分で掃除しなさい (at the very least, clean your own room yourself). In this meaning you can't substitute ほど: ほど measures a high degree, while くらい pulls things down to a low one.
くらい and ぐらい are nowadays freely interchangeable in every position; ぐらい sounds just slightly more colloquial. A quick trick for telling it apart from ほど: 死ぬほど疲れた stresses "unbelievably tired," while これくらいの練習 stresses "this much practice is nothing."
Examples
歩けないくらい足が痛いです。
My leg hurts so much I can't walk.
自分の部屋ぐらい自分で掃除しなさい。
At the very least, clean your own room yourself.
恥ずかしくて泣きたいくらいでした。
I was so embarrassed I wanted to cry.