"Мы в трёх часах езды от Бостона."

I came across this sentence in Russian, and it seemed wrong to me. I would have expected час to either be in genitive singular case (часа) since we have the numeral трёх before it, or perhaps singular prepositional (часе) because of the в.

Can someone help me figure out how to correctly deconstruct this sentence from a case perspective?

2 Answers 2


Whenever you need to figure out case, just look to the preposition as a guide. For instance, the preposition в is only used with the accusative and prepositional cases, not with the genitive.

В трех часах езды - refers to a measure, a degree (of time, space, quantity). The word час here indicates not the astronomical time, but how far away the object is in distance.

Similar phrases: в километре от станции, в трех минутах ходьбы, съесть в большом количестве, рассказать в двух словах.


The genitive singular is used after the numerals два, три, четыре and оба only when the numeral is in the nominative or the accusative case. For all the other cases, both the numeral and the following noun take that case (with the noun in the plural):

N. три часа
G. трёх часов
D. трём часам
I. тремя часами
P. трёх часах

In your example both words are in the prepositional case because they're governed by the preposition «в».

See this declension tool when in doubt.

  • 1
    Minor note: that declension tool produces incorrect stress position for those few irregular words (час, ряд, шаг, шар) that have a special counting form instead of genitive singular.
    – Igor G
    Commented Jan 4, 2023 at 17:46
  • 1
    @IgorG, it's fixed now. Thanks for flagging it up! Commented Jan 4, 2023 at 20:36
  • another note, not sure how easy to fix: болгарских левов, киргизских со́мов, перуанских со́лей. In general, a very nice tool, thank you very much!
    – Quassnoi
    Commented Jan 4, 2023 at 22:28

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