Grammar Info

N3 Lesson 8: 8/23


Repeated at intervals, Every other, Every, At intervals of


Number + Counter + おきに


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About おきに

()きに is a combination of ()き, a suffix meaning 'opening' or 'interval', and the case marking particle に. Primarily written without kanji, it is an expression used to show that something happens 'every (A)', or 'at intervals of (A)'.
The difference between something being interpreted as 'every', or 'at intervals of' can be tricky though, so we'll look at both.
Due to おきに being a suffix, it will be attached to the end of numbers, counters, or any 'space' that it is highlighting as being an 'opening' or 'interval'.
  • この(くすり)一日(いちにち)おきに()んでください。
    Please drink this medicine at intervals of one day. (Every second day)
  • 一ヶ月(いっかげつ)おきに病院(びょういん)()ように先生(せんせい)()われました。
    I was told by the doctor to come to the hospital at intervals of one month. (Every second month)
  • 二日(ふつか)おきに部屋(へや)掃除(そうじ)ないと()()()かない
    I can't relax if I don't clean my room at intervals of two days. (Every three days)
Looking at these sentences, we can see that the 'interval' is a bit difficult to understand even in English. However, the easier way to think of おきに in this sense is 'leaving a space of (A), (B)'. So if we say 'leaving a space of two days, (B)', it becomes a bit clearer that something is happening during the third day.
It is very common to get ごとに and おきに mixed up. The former literally means 'every'. However, the latter having the meaning of 'at intervals' makes things confusing. おきに itself will only mean 'every' sometimes. Let's look at some examples of when these two expressions overlap in meaning, and when they do not.
Large time frames or distances - Only ごとに will be used to express 'every'. It makes sense to ask 'at what point' during a day, a week, or a month. Due to this, only おきに will mean 'after the interval of (A)', while ごとに means 'every'.
  • 一日(いちにち)ごとに目薬(めぐすり)()す。
    I use my eye drops every day. (It doesn't matter what part of the day, but it does happen every day)
  • 一日(いちにち)おきに目薬(めぐすり)()す。
    I use my eye drops every second day. (It makes sense to wonder when it may occur during the second day, but we know it doesn't happen for at least an interval of one whole day)
Small time frames or distances - Both ごとに and おきに may be used to express 'every'. It doesn't make sense to care about 'at what point' during seconds, minutes, or hours. Here, because おきに points at the interval, it will mean 'every interval of one second' etc, because nobody is going to ask 'when did (B) happen during the next second', so the space is just assumed to be 'one second'.
  • 毎日(まいにち)2時間(じかん)ごとに(からだ)(うご)かしている
    I move my body every two hours, every day. (At some point during every group of 2 hours)
  • 毎日(まいにち)2時間(じかん)おきに(からだ)(うご)かしている
    I move my body every two hours, every day. (After every interval of two hours. Nobody cares about 'when during the third hour', so we just understand it as 'every two hours')
In summary, おきに will mean 'every (A)' for seconds, minutes, hours, millimeters, centimeters, and kilometers. But it will mean 'with spaces of' for almost anything bigger than that. This is not an exception to the rule, it is just a change of focus as spaces get larger. We can just remember that おきに always has one job. It highlights that (B) occurs after or outside of (A). While ごとに highlights (B) happening within (A).
一秒(いちびょう)おきに - The space is 'one second', so if おきに points to the beginning of the next second, the space is still only 'one second'. Because おきに doesn't care about where (B) happens within that next second, we assume straight away.
五年(ごねん)おきに - The space is 'five years', so if おきに points to the beginning of the next year, the space becomes 'six years', because we are going to want to know where (B) happens within that next year. It would be strange to assume someone is waiting for New Year of the sixth year to do something instantly.
Fun Fact
This is a topic that native speakers frequently get wrong themselves, so don't worry if it takes a while to understand! If you are unsure about which one to use, think of ()きに as 'leaving intervals of (A), (B)' for most purposes. 一時間(いちじかん) tends to be the upper limit of time that most people disagree about whether the meaning is 'every hour', or 'every second hour'. This makes sense, as the time frame is short, but still sort of long, so whether someone takes it as the beginning of the hour or some point during that hour being the important information, their opinions may differ. Remember though, おきに itself only ever points to the beginning of the space after (A), it doesn't care when/where (B) happens afterward.




    Please check the temperature every other hour.


    We change the water of the fish tank every other week.


    Let's take a break in intervals of 30 minutes.


    I've heard that you can feed goldfish every second day.


    In this area, every other house is subscribed to the newspaper.

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おきに – Grammar Discussion

Most Recent Replies (29 in total)

  • casual


    Looking at the example sentences within the description, I like how this one is clarified:

    at intervals of one month. (Every second month)

    If all test sentences that use the expression “at intervals” would be also clarified like that, that would help. For example:

    at two-year intervals (every 3 years)

    As is currently, I’m still not sure if you agreed with Eroliene’s and my feedback on that sentence or not. The Japanese one is asking for the answer 2年おきに, which means every 3 years, but the English translation means every 2 years.

  • Inounx


    I will try to give some feedback, but keep in mind that I don’t master perfectly this grammar point !

    First, I find that the meaning “sometime during” and “sometime after” are confusing. There is no notion of occurence and repetition. The other meaning you use in the grammar page “every occurence of (A)” for ごとに and “leaving (A) between each occurence” for おきに seems much clearer.

    I think that the new explanation is globally more understandable, but this part is still confusing for me :

    We can just remember that おきに always has one job. It highlights that (B) occurs after or outside of (A). While ごとに highlights (B) happening within (A).
    一秒いちびょうおきに - The space is ‘one second’, so if おきに points to the beginning of the next second, the space is still only ‘one second’. Because おきに doesn’t care about where (B) happens within that next second, we assume straight away.
    五年ごねんおきに - The space is ‘fi...

  • Asher


    Will fix this. Could even change it to ‘with a gap of’ if that makes more sense (see diagram below)

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