по vs за

po vs za — along/by/per vs behind/for/within

What it really means

По and за have many meanings, so English "by," "for," or "along" is not enough to choose between them. По commonly marks movement along or around a place, a route or medium, distribution, and a rate: по улице (along the street), по телефону (by phone), по два яблока (two apples each). За commonly marks behind a place, exchange or support, substitution, or the time needed to complete something: за домом (behind the house), платить за билет (pay for the ticket), сделать за час (do it in an hour).

The prepositions also govern different cases in different meanings. Learn the complete construction rather than treating по and за as interchangeable translations of "for."

Examples in natural speech

Мы гуляли по улице.
We walked along the street.
Я узнал новости по телефону.
I heard the news by phone.
Дайте по два яблока каждому.
Give two apples to each person.
Машина стоит за домом.
The car is behind the house.
Я заплатил за билет.
I paid for the ticket.
Он сделал работу за час.
He completed the work in an hour.

Common mistakes

Do not choose по for every English "by" or за for every English "for." По телефону means by phone, but за автобусом means behind/after the bus; по два means two each, while за два часа means within two hours. The noun case depends on the construction.

Memory tip

По traces a route, medium, or distribution; за marks behind, exchange/support, substitution, or a completion limit.

Frequently asked questions

What is the difference between по and за in Russian?

По can mean along, by a medium, according to, or per: по улице, по телефону, по два. За can mean behind, for/in exchange, on someone’s behalf, or within a duration: за домом, платить за билет, за час.

How do you say by phone in Russian?

Say "по телефону." По marks the communication medium in this expression. It is different from за телефоном, which would mean behind or near the phone.

Why is it за час but по часам?

За час means within one hour or in the time needed to finish something. По часам means by the clock or according to the hours, because по expresses a reference or distribution pattern.

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