When on earth do you use ごろ (goro)?

Question

I was in class the other day and my せんせい was teaching us about using ぐらい (gurai) as in ...どの ぐらい かかりますか (how long will it take), and mentioned another form of ぐらい being ごろ (goro), and never elaborated on how or when to use it. Can anyone explain it to me?

Answer 1

In English, ～ぐらい and ～ごろ mean about, around, approximately.

1. ～ぐらい is used for approximate quantities, which include duration.

   1. このXはいくらぐらいですか。About how much is this X?
      そのXは５００円ぐらいです。 That X is about 500 yen.
   2. 六時間ぐらい図書館にいました。I was at the library for about 6 hours.　

2. ～ごろ is used for approximate points in time, with an optional に.

   1. 八時ごろ（に）公園に来ました。I came to the park around 8.
   2. 六時ごろ帰ります。I will return around 6.

You cannot use ～ごろ in 1. Some people use ～ぐらいに in 2, but I do not know enough to comment further on that usage.

By the way, I think 「どのぐらいかかりますか」 is more accurately "About how long will it take?"