За vs Через (time and reason) | Ukrainian Grammar

English "in an hour" is doing two opposite jobs and never tells you which. "I'll finish it in an hour" means the work fills the hour — it is a duration. "I'll call you in an hour" means nothing happens for an hour and then I call — it is a delay. Ukrainian refuses to let these collapse into one phrase: the duration reading is за годи́ну (за + accusative), and the delay reading is че́рез годи́ну (через + accusative). Pick the wrong one and you have reversed the timing. On top of that, через has a second life as the everyday word for "because of" — and за never does. This is the decision page; the wider behaviour of each preposition lives on the через/про/за in time page and the за preposition page.

The quick answer

Ask what the hour measures. If the hour is the time the action takes — you do it and you are done within that span — use за + accusative (за годи́ну зроблю́ "I'll get it done within an hour"). If the hour is empty waiting and the action happens after it runs out, use че́рез + accusative (че́рез годи́ну прийду́ "I'll come in an hour / an hour from now"). For a cause — "because of the rain," "because of you" — it is always че́рез + accusative; за cannot mean "because of."

	за + accusative	через + accusative
Time meaning	within / by the end of the span (duration)	after the span elapses (a delay from now)
The hour is…	how long the action takes	the wait before the action starts
English	"in / within an hour", "in an hour flat"	"in an hour", "an hour from now", "after an hour"
Example	Я зроблю́ це за годи́ну.	Я прийду́ че́рез годи́ну.
"because of"?	no — за has no causal use	yes — че́рез дощ "because of the rain"

Time, part 1: за + accusative = "within / by the end of the span"

За + accusative answers how long did / will the action take? The span is the container the action fits inside: you start, and by the time it runs out you are finished. English usually translates this with "in" in the sense of "in an hour flat," or with "within." The action and the span are one and the same stretch of time.

Я зроблю́ це за годи́ну — не хвилю́йся, всти́гну.

I'll get it done within an hour — don't worry, I'll have time. (The hour is how long the work takes → за.)

Вона́ ви́вчила всю те́му за оди́н ве́чір.

She learned the whole topic in a single evening. (The evening is the span the learning filled → за.)

Ми дої́хали до Льво́ва за п’ять годи́н.

We got to Lviv in five hours. (The five hours are the duration of the trip → за.)

Notice the verb is typically perfective here (зроблю́, ви́вчила, дої́хали): you are reporting that the action reached completion within the span. That pairing — perfective verb + за + accusative — is the signature of the "within" reading.

Time, part 2: через + accusative = "after the span / from now"

Че́рез + accusative answers how long until it starts? Nothing happens during the span — it is empty waiting — and the action lands at the far end of it. From the present moment you count forward the stated amount of time, and then the event occurs. This is the reading English speakers most often want when they say "in an hour."

Я прийду́ че́рез годи́ну, заче́кай на ме́не.

I'll come in an hour — wait for me. (An hour passes, then I arrive → через.)

По́їзд відправля́ється че́рез два́дцять хвили́н.

The train leaves in twenty minutes. (Twenty minutes of waiting, then departure → через.)

Передзвоню́ тобі́ че́рез п’ять хвили́н, за́раз зайня́тий.

I'll call you back in five minutes, I'm busy right now. (A delay, not a duration → через.)

💡

The one-line test: replace "in" with "after" and see if the meaning survives. "I'll call you after an hour" works — it is a delay → че́рез годи́ну. "I'll finish it after an hour" does not mean what you intend (you mean it takes an hour) → that is за годи́ну. "After" passes only the через cases.

The contrast is sharpest in a minimal pair. Я зроблю́ це *за годи́ну = "I'll have it done within the hour" (you can expect the result in 60 minutes' work). Я зроблю́ це че́рез годи́ну* = "I'll start on it an hour from now" (you should not expect anything for the next hour). Same noun, opposite logistics.

— Коли́ бу́де гото́во? — За годи́ну, я вже почина́ю.

'When will it be ready?' 'Within an hour, I'm starting now.' (Duration → за.)

— Коли́ бу́де гото́во? — Че́рез годи́ну, за́раз не мо́жу.

'When will it be ready?' 'In an hour — I can't right now.' (Delay before starting → через.)

Reason: через + accusative = "because of"

The second job of через has nothing to do with time: че́рез + accusative is the ordinary, neutral way to say "because of" — to name the cause of something, very often something unwelcome. За never does this. If you can paraphrase with "because of" or "due to," reach for через.

Ми запізни́лися че́рез за́тор на доро́зі.

We were late because of a traffic jam. (Cause of being late → через + accusative.)

Рейс скасува́ли че́рез пога́ну пого́ду.

The flight was cancelled because of bad weather. (Cause → через.)

Че́рез тебе́ ми пропусти́ли поча́ток фі́льму!

Because of you we missed the start of the film! (Cause, with a person → через + accusative тебе́.)

💡

For a positive cause — "thanks to," "owing to" a good thing — Ukrainian prefers завдяки́ + dative (завдяки́ тобі́ "thanks to you"), reserving через for neutral or negative causes. Saying че́рез тебе́ after something good ("we won because of you") sounds like blame; use завдяки́ тобі́ instead.

Source-language comparison

For an English speaker, the trap is the word "in." English "in an hour" is genuinely ambiguous — "I'll finish it in an hour" (duration) and "I'll call you in an hour" (delay) use the identical phrase, and you sort them out from context. Ukrainian forces the choice up front: duration is за годи́ну, delay is че́рез годи́ну. The good news is that you already feel the difference; you just have to attach it to two different prepositions. The reliable move is the "after" test — only the delay cases tolerate "after an hour."

For a Russian speaker, the time split is the same idea but the words shift. Russian uses за час for the duration ("сделаю за час") just like Ukrainian, so that half transfers cleanly. For the delay, Russian uses через час, also matching. The real divergence is "because of": Russian leans on из-за (из-за дождя), whereas standard Ukrainian uses че́рез (че́рез дощ). Importing із-за is a common interference error — though it is heard regionally, the neutral literary form is через.

Common Mistakes

❌ Я прийду́ за годи́ну — заче́кай на ме́не.

Incorrect for 'an hour from now': a delay before arriving is че́рез годи́ну. За годи́ну would mean 'I'll manage the arriving within an hour', which is not what you mean.

✅ Я прийду́ че́рез годи́ну — заче́кай на ме́не.

I'll come in an hour — wait for me. (Delay → через.)

❌ Не хвилю́йся, я все зроблю́ че́рез годи́ну.

Incorrect if you mean 'it'll take me an hour': duration is за годи́ну. Че́рез годи́ну says you won't even start for an hour.

✅ Не хвилю́йся, я все зроблю́ за годи́ну.

Don't worry, I'll get it all done within an hour. (Duration → за.)

❌ Ми запізни́лися за за́тор на доро́зі.

Incorrect — 'because of' is never за. The cause of being late is че́рез за́тор.

✅ Ми запізни́лися че́рез за́тор на доро́зі.

We were late because of a traffic jam. (Cause → через.)

❌ Рейс скасува́ли із-за пога́ної пого́ди.

Incorrect — із-за for 'because of' is Russian transfer; standard Ukrainian uses че́рез + accusative.

✅ Рейс скасува́ли че́рез пога́ну пого́ду.

The flight was cancelled because of bad weather.

❌ Че́рез тебе́ ми ви́грали — ти найкра́щий!

Off-key — though grammatical, че́рез names a negative cause (blame). For a positive cause use завдяки́ + dative.

✅ Завдяки́ тобі́ ми ви́грали — ти найкра́щий!

We won thanks to you — you're the best! (Positive cause → завдяки́ + dative.)

Key Takeaways

За + accusative (time) = within / by the end of the span — how long the action takes: за годи́ну зроблю́ "I'll get it done within an hour." Usually with a perfective verb.
Че́рез + accusative (time) = after the span elapses, from now — a delay before the action starts: че́рез годи́ну прийду́ "I'll come an hour from now."
The "after" test: if "after an hour" fits, it is через; if you really mean the work takes an hour, it is за.
"Because of" is че́рез + accusative, never за: че́рез дощ "because of the rain." For a positive cause use завдяки́ + dative.
Russian-speaker watch-out: через, not із-за, for "because of" in standard Ukrainian.

Now practice Ukrainian

Reading grammar gets you part of the way. The exercises are where it sticks — free, no signup needed.

Start learning Ukrainian→