Introduction
Want to say things like:
- “I go shopping once a month”?
- “I brush my teeth three times a day”?
- “I travel abroad about three times a year”?
In Japanese, to express how often something happens in a given period, we use a very clear pattern:
（period）に（frequency）
= (frequency) in (period)
Let’s master this structure to talk naturally about daily habits and schedules!
1. Grammar Structure
Pattern:（period）に（frequency）
| English | Japanese |
|---|---|
| once a month | 一ヶ月に一回 |
| three times a week | 一週間に三回 |
| three times a day | 一日に三回 |
2. How to Form It
| Step | Explanation |
|---|---|
| ① Choose the period | 一日 (a day), 一週間 (a week), 一ヶ月 (a month), 半年 (half year), 一年 (a year), etc. |
| ② Use the particle に | に = in (indicating time period) |
| ③ Add the frequency | 一回 or 一度 (once), 二回 or 二度 (twice), 三回 or 三度 (three times), etc. |
3. Example Sentences
- 一週間に二回スーパーに行きます。
= I go to the supermarket twice a week. - 一年に一回海外旅行をします。
= I travel abroad once a year. - 一日に三回お茶を飲みます。
= I drink tea three times a day. - 一ヶ月に一回、ボランティアをします。
= I volunteer once a month. - この町では半年に一度、お祭りが開かれます。
= This town holds a festival every six months.
4. Tips: How to count days
| Japanese (Words) | Meaning | Example Sentence (Japanese) | Example Sentence (English Translation) |
|---|---|---|---|
| 二日 | two days | 二日に一回、日本語の授業があります。 | I have a Japanese class once every two days. |
| 三日 | three days | 三日に一回ギターを練習します。 | I practice the guitar once every three days. |
| 四日 | four days | 四日に一回洗濯をします。 | I do the laundry once every four days. |
| 五日 | five days | 五日に一回友だちに電話します。 | I call my friends once every five days. |
| 六日 | six days | 六日に一回レポートを書きます。 | I write a report once every six days. |
| 七日 | seven days | 七日に一回アルバイトをします。 | I do a part-time job once every seven days. |
| 八日 | eight days | 八日に一回車を洗います。 | I wash the car once every eight days. |
| 九日 | nine days | 九日に一回テニスをします。 | I play tennis once every nine days. |
| 十日 | ten days | 十日に一回部屋を掃除します。 | I clean my room once every ten days. |
5. Tips: Useful Expression くらい（about / approximately）
You can add くらい after the frequency to express “about ~ times”:
旅行は好き？
Do you like to travel?
大好き！一年に五回くらい海外に行くわ。
I love it! I go abroad about five times a year.
何か運動してる？
Are you working out at all?
うん、週に二回くらいジムに通ってる。
Yeah, I hit the gym about twice a week.
Note: くらい makes your statement softer and more natural in conversation.
6. Common Mistakes to Avoid
| ❌ Wrong | ✅ Correct | Why: |
|---|---|---|
| 一週間で三回 | 一週間に三回 | Always use に after the period |
| 三回に一週間 | 一週間に三回 | ✅(period) に (frequency) |
🔵 Remember:
- Always use に after the period.
- The correct order is period に frequency — not the other way around!
7. Practice Time!
Try creating sentences using （period）に（frequency）！
| Prompt | Example Answer |
|---|---|
| Exercise three times a week | 一週間に三回 運動します。 |
| Drink tea five times a day | 一日に五回お茶を飲みます。 |
| Travel once a year | 一年に一回 旅行します。 |
| Ride the bus about six times a month | 一ヶ月に六回くらいバスに乗ります。 |
| Sleep about seven hours a day | 一日に七時間くらい寝ます。 (using hours instead of 回) |
8. FAQ – Frequently Asked Questions
- QCan I use this pattern with periods other than just “one day/week/month/year” or “X days,” like “every two months” or “every half year”?
- A
Yes, absolutely. The “period” part can be any duration. Examples:
- 二ヶ月に一回髪を切ります。(Nikagetsu ni ikkai kami o kirimasu.) = I cut my hair once every two months.
- 半年に一度健康診断を受けます。(Hantoshi ni ichido kenkou shindan o ukemasu.) = I get a health check-up once every half year.
- 四年に一回オリンピックがあります。(Yonen ni ikkai Orinpikku ga arimasu.) = The Olympics happen once every four years.
- QCan I skip the に particle?
- A
No — に is essential to show the time relationship!
- QCan I use くらい with both period and frequency?
- A
No — use くらい after the frequency.
✅一日に二回くらい ／ ✖ 一日くらいに二回
- QHow is this pattern different from using words like 「毎日」(every day) or 「毎週」(every week)? Can I use them together?
- A
Words like 「毎日」(every day), 「毎週」(every week), 「毎月」(every month), 「毎年」(every year) already specify both the period AND the frequency (which is implicitly “every” or “each”). You cannot use them with the 「（period）に（frequency）」 pattern.
- OK: 毎日テニスをします。= I play tennis every day.
- NG: 毎日に一回テニスをします。
- QHow is this pattern different from simply stating how long you did something (duration)?
- A
This pattern expresses the frequency of an event within a specific period, whereas stating duration expresses the total length of time an action lasted.
- Frequency: 一日に七時間寝ます。(Ichinichi ni shichi-jikan nemasu.) = I sleep seven hours a day. (Focuses on how many hours of sleep occur within one day).
- Duration: 七時間寝ました。(Shichi-jikan nemashita.) = I slept for seven hours. (Focuses on the total length of the sleeping time).
- QWhat kinds of words or phrases can be used for the “frequency” part after the particle 「に」? Is it only 「〜回」?
- A
No. The “frequency” part is typically a number followed by any appropriate counter, or sometimes specific fixed frequency words.
Number + Counter: This is the most common. The counter indicates what is being counted (e.g., 回 for occurrences, 時間 for hours, 人 for people, 冊 for books, etc.).
- 一日に三冊本を読みます。(Ichinichi ni san-satsu hon o yomimasu.) = I read three books a day.
- 一週間に二人の友達に会います。(Isshuukan ni ni-nin no tomodachi ni aimasu.) = I meet two friends a week.
- 週に一時間プログラミングの勉強をします。(Shuni ichijikan puroguramingu no benkyo wo shimasu.) = I study programming for an hour every week.
Fixed Frequency Words: Sometimes words like 「一度 (ichido – once)」 are used.
- Example: 一生に一度の経験です。(Isshou ni ichido no keiken desu.) = It’s a once-in-a-lifetime experience.
9. Conclusion
Now you can:
✅ Say how often you do something in Japanese
✅ Use （period）に（frequency） naturally
✅ Avoid common word order mistakes!
🎯 Try this:
Talk about your daily or weekly routines using the structure you learned!
Want to improve your Japanese with real conversations?
Our native Japanese instructors at gokigen japanese can help you perfect your pronunciation and learn real-life usage.
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