〜くらい / 〜ぐらい

about / at least

"About" with numbers, "at least" or "just" with nouns, and "so…that" for degree.

Readings

How to form it

After a number or amount, it means "about": 三十分(さんじゅっぷん)ぐらい (about thirty minutes).
After a noun, it can play something down, "at least" or "just": 挨拶(あいさつ)ぐらいできる (you can at least say hello).
After a verb or adjective, it shows degree: 動(うご)けないくらい疲(つか)れた (I was so tired I couldn't move).
くらい and ぐらい mean the same.

三十分(さんじゅっぷん)ぐらい待(ま)ちました。

I waited about thirty minutes.

挨拶(あいさつ)ぐらいはできるでしょう。

You can at least say hello, surely.

For a point in time, use ごろ: 三時(さんじ)ごろ (around three o'clock), but 三時間(さんじかん)ぐらい (about three hours).