I feel it is safe to say that outside of any context, когда-то defaults to meaning "at some point in the past", at least in the dialect I am speaking. I might even go so far as to say that that's the only meaning I use it in myself.

However, every once in a blue moon, I run into it being used to mean "at some point in the future". And it usually immediately sticks out. Even to the point of sounding ungrammatical.

I'm struggling to think of sample quotes right now, except for this rather famous one:

Детство кончится когда-то,
Ведь оно не навсегда.
Станут взрослыми ребята,
Разлетятся кто куда.

Now, that's none other than Entin right there, so I suppose he knew full well what he was doing. When I sing it I might not even notice or care. But when reading it, and stopping to think about it, I quickly realize that I really want that когда-то to be a когда-нибудь. Heck, even a когда-либо would be a more natural choice for me. At best, the когда-то feels like a one-off poetic-license type of thing; at worst, it makes me sound like a German spy blowing his cover.

Consequently, my question is: is this a one-off thing? Knowing the rules so you can break them? Or did I just happen to acquire a dialect where this is unusual, but other than that it is something well-attested going back hundreds of years? Perhaps even quite typical for other dialects (or registers)?

I would appreciate any pointers to research on the subject, or, failing that, a bunch of citations. While I mean no disrespect to Mr Entin, I'd be lying if I said that seeing this from someone of the caliber of a Lermontov or a Chekhov wouldn't be more convincing.

  • 2
    "Когда-то" is "once", it can refer to both the past and the future.
    – Yellow Sky
    Commented Dec 23, 2013 at 21:56

5 Answers 5


I would say, the difference between когда-то and когда-нибудь is somewhat similar to the difference between definite and indefinite article. "Когда-нибудь" means "at some time" or "some day", "когда-то" means "at certain time" or "one day". Compare:

Если много играть в эту лотерею, то когда-нибудь выиграешь.

If you play this lottery much, you will win some day.

This means that one can hope to win in this lottery only statistically, without solid knowledge of inevitable win.

Если много играть в эту лотерею, то когда-то выиграешь.

If you play this lottery much, you will win one day.

This means, one can be sure that the win is inevitable not only statistically but the win is pre-determined (for example because the win is guaranteed to all players before all the tickets are spent).

Наш город когда-нибудь станет крупным промышленным центром.

Some day our city will become a big industrial center.

One can reasonably hope that the city will become an industrial center in uncertain future.

Наш город когда-то станет крупным промышленным центром.

One day our city will become a big industrial center.

The city will become the industrial center for sure, this is in the plan, and the date even may be known.

Когда-нибудь я стану руководителем завода.

Some day I will become a factory manager.

This can be said by a successful employee.

Когда-то я стану руководителем завода.

One day I will become a factory manager.

This can be said by a heir to an industry tycoon.

Когда-нибудь мы все умрём.

Some day we all will die.

This may be said by a healthy person living in natural conditions.

Когда-то мы все умрём.

One day we all will die.

This may be said by a person anticipating a disaster or speaking about a terminally ill group of people.

It is of no surprise that когда-нибудь is more often used for the future (like "some day"), while когда-то is more often used for the past (like "one day", "once"). This is because one can be more certain about events in the past than about events in the future.

Speaking with mathematical language, one can say that "когда-нибудь" means

enter image description here

and "когда-то" means

enter image description here

where p(t) is the probability distribution of the event, t0 is the present moment and t1 is some moment in the future.

  • 1
    The difference between ‘some day’ and ‘one day’ in your translations is extremely slight and gives the impression of being more of a literary device here. Of course this is just an English issue and the explanations make it sufficiently clear what’s meant.
    – Valiowk
    Commented Dec 24, 2013 at 18:14
  • 1
    You seem to be right. The particle -то comes from pronoun тот which used to serve as a definite article and is still being used like that in Bulgarian. However, the more I think about its usage for future, the more controversial it looks to me.
    – jwalker
    Commented Dec 24, 2013 at 20:26
  • 3
    +1 for last three lines ... :)
    – c.p.
    Commented Jan 3, 2014 at 11:42
  • 1
    Wonderful! Made me smile =) Are you currently studying probability theory and statistics?
    – petajamaja
    Commented Jan 5, 2014 at 17:26

This in fact it is "playing by the rules". Let's use the dictionaries. Ushakov's dictionary:

КОГДА́-ТО, нареч.
1. Некогда, в прошлом. Когда-то мы были знакомы. «Царь Никита жил когда-то славно, весело, богато.» Пушкин.
2. Неизвестно когда в будущем. Когда-то он соберется! Когда-то еще выпадет такой счастливый случай!

Same entry is in Efremova's dictionary. Also the "Большой англо-русский и русско-английский словарь" gives the following examples of using "когда-то" to refer the future:

2) (в будущем) we shall have a long time before...; it will be a long time before... когда-то еще будет такой приятный вечер ≈ it will be a long time before we have such a pleasant evening again

2) (в будущем) : когда-то мы опять увидимся! who knows when we shall meet again!; когда-то он придёт! will he ever come!


Когда-то means at some point in time except now. Used not for near time. But period may even one day if this is significant.


Excellent question! Wiktionary says that the usage of когда-то to mean "at some point in the future" is a colloquialism.

A quick google search did not return any quotes from someone of the caliber of Lermontov or Chekhov, but it did find this song by Vysotsky. ;)

Now that I think about this, когда-нибудь can also mean past or future. This seems to be equivalent to "at some point" in English. As in "Will you do this at some point?" or "Have you done this at some point?" I guess you just have to go by the tense of the verb here.

  • 1
    I would not trust Wiktionary. It’s funny to see ‘Когда-то и нас ведь не станет, и мы, превратившись во прах,…’ as example of colloquial speech. Commented Dec 27, 2013 at 13:14

I don't think any native Russian speaker would use "когда-то" in future tense, no matter whether talking about definite or probable event. If one wants to emphasize certainty, it's better to skip this word altogether: One day I will become a factory manager = "я обязательно стану директором завода".

Your quote is clearly a case of poetic license: a slight deviation from rules to fit the rhythm.

  • "я обязательно стану директором завода" can be said by an employee to express confidence or hope. A heir will not say it this way.
    – Anixx
    Commented Dec 28, 2013 at 2:09
  • "Когда-то мы еще с тобой погуляем в парке" which can be roughly translated as "I'm not sure if we ever get the chance to walk in the park in the future".
    – Artemix
    Commented Dec 31, 2013 at 8:04
  • @Artemix opposite. This means the speaker is sure this will happen. At least, he planned so for himself, for example "Когда-то, когда меня выпустят из тюрьмы, мы еще с тобой погуляем в парке".
    – Anixx
    Commented Jan 2, 2014 at 16:16
  • @Anixx No, I think the speaker wants it to happen, but not sure if it will.
    – Artemix
    Commented Jan 3, 2014 at 2:19

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