（期間）に（回数）

To express frequency — how many times you do something within a period of time — use the pattern: time period + に + number of times: 週に三回 (three times a week), 月に一回 (once a month), 一日に二回 (twice a day).

The particle に here doesn't mark a specific point in time as you learned at N5 (七時に起きます); it marks the time unit serving as the base, meaning "per…". The count usually uses 〜回, but it can also be 〜度 or some other quantity: 週に一度 (once a week), 一日に三時間 (three hours a day).

When asking and answering about frequency, this pattern is the most natural way to say it: 「一週間に何回日本語の授業がありますか」—「三回あります」. If you're only estimating, add ぐらい after the count: 週に二回ぐらい.

Examples

• 週(しゅう)に三回(さんかい)、日本語(にほんご)を勉強(べんきょう)します。

  I study Japanese three times a week.

• 月(つき)に一回(いっかい)、映画(えいが)を見(み)に行(い)きます。

  I go to see a movie once a month.

• 一日(いちにち)に二回(にかい)、歯(は)を磨(みが)きます。

  I brush my teeth twice a day.

Related patterns

• 〜目
• 数量詞＋も