The Many Uses of По | Russian Grammar

If one preposition deserves a page of its own, it is по. English splits its work across "along," "around," "on," "by," "according to," "about," and "per" — Russian funnels nearly all of it into a single word governing a single case: по + dative. Because по is so frequent, mastering its handful of senses unlocks a large slice of natural Russian at once. The trick is not to translate the English preposition word-for-word, but to recognize the relationship — path, medium, criterion, routine, distribution — and let it trigger по + the dative. (For its case behaviour alongside к, see dative after к and по.)

По takes the dative — almost always

In every everyday sense below, по governs the dative. There is a minority по + accusative ("up to a limit"), saved for the end. When you hear по, default to the dative.

Sense	Example	English
motion along / over	идти́ по у́лице	walk along the street
by means of / via	по телефо́ну	by phone
according to / by	по пла́ну	according to plan
subject / field	экза́мен по фи́зике	a physics exam
regular days / times	по понеде́льникам	on Mondays
distribution	по одному́	one each
because of	по оши́бке	by mistake

1. Motion along / over a surface

The spatial core: moving along a line or around/over an area. Unlike в/на + accusative (which mark a destination), по marks the path or territory covered, with no single endpoint.

Мы до́лго гуля́ли по па́рку и не уста́ли.

We strolled around the park for ages and didn't get tired. — по + dative па́рку: wandering over the area.

Не бе́гай по у́лице, там маши́ны!

Don't run in the street, there are cars! — по у́лице: motion up and down along the surface.

2. By means of / via a medium

По + dative is the standard way to say something travels by or over a channel: by phone, by mail, over the internet, on TV.

Бы́стрее реши́м э́то по телефо́ну.

Let's sort this out faster by phone. — по телефо́ну: the medium of communication.

Я ви́дел э́то по телеви́зору и в интерне́те.

I saw it on TV and on the internet. — по телеви́зору, по интерне́ту, по по́чте all use по + dative for the channel.

💡

"On the phone / on TV" as a medium is по + dative (по телефо́ну, по телеви́зору), not на. На телефо́не means physically sitting on top of the device. The relationship is transmission through a channel.

3. According to / by a criterion

По + dative covers according to a plan, an opinion, a law, a rule — the standard or yardstick something follows.

Всё идёт стро́го по пла́ну.

Everything is going strictly according to plan. — по + dative пла́ну.

По мне́нию враче́й, э́то безопа́сно.

According to the doctors, it's safe. — по мне́нию + genitive of the source; the shorter по-мо́ему means 'in my opinion'.

Он поступи́л по зако́ну и по со́вести.

He acted within the law and his conscience. — по зако́ну, по со́вести: by the criterion.

4. The subject / field of study

По + dative names the subject area of an exam, textbook, teacher, coach, or specialist — where English says "in / on / of" for a field.

За́втра у меня́ экза́мен по матема́тике.

I have a maths exam tomorrow. — экза́мен по + dative матема́тике: the subject of the exam.

Э́то лу́чший уче́бник по фи́зике.

This is the best physics textbook. — уче́бник по + dative фи́зике; likewise тре́нер по пла́ванию (swimming coach), специали́ст по исто́рии (history specialist).

5. On regular days and times

A learner favourite: по + dative plural means every / on (regularly) — recurring days and times of day.

По понеде́льникам у меня́ трениро́вка.

On Mondays I have training. — по + dative plural понеде́льникам: every Monday.

По утра́м я бе́гаю, а по выходны́м — сплю.

In the mornings I run, and on weekends I sleep. — по утра́м, по выходны́м: habitual times.

💡

Recurring vs. one-off: "on Mondays" (every Monday) = по понеде́льникам (по + dative plural). A single specific "on Monday" = в понеде́льник (в + accusative). Both the preposition and the case change with the meaning.

6. Distribution — "X each"

По distributes a quantity over recipients — "one each, two apiece." With оди́н it gives the dative по одному́; with higher numbers usage varies, but the everyday phrases are fixed.

Раздай ка́ждому по одному́ ли́сту.

Give everyone one sheet each. — по одному́: distributive 'one apiece'.

Возьми́те по две конфе́ты, не бо́льше.

Take two sweets each, no more. — по две конфе́ты: distributive 'two apiece'.

7. Because of / by (mistake, reason)

A small set of fixed phrases uses по + dative for cause — usually an unintentional or accidental reason: by mistake, for some reason, due to illness.

Я взял твой зо́нтик по оши́бке, извини́!

I took your umbrella by mistake, sorry! — по оши́бке: accidental cause.

Он не пришёл по боле́зни.

He didn't come due to illness. — по боле́зни; likewise по причи́не ('because of'), по како́й-то причи́не ('for some reason').

A note on the rarer по + accusative

The dative dominates по, but there is an older по + accusative meaning up to and including (a limit), found in dates, ranges, and a few set phrases: с пе́рвого по пя́тое число́ ("from the 1st to the 5th inclusive"), по́ пояс в воде́ ("up to the waist in water"). Treat it as a separate idiom set. Note the difference from до: до пя́того excludes the 5th, по пя́тое includes it.

О́тпуск с пе́рвого по деся́тое ию́ля.

Holiday from the 1st to the 10th of July, inclusive. — по + accusative деся́тое: the upper limit, included.

Common Mistakes

❌ Мы гуля́ли по па́рк.

Wrong — по governs the dative, so 'around the park' is по па́рку, not the bare accusative по парк.

✅ Мы гуля́ли по па́рку.

We walked around the park. — по + dative.

❌ Поговори́м на телефо́не.

Wrong — 'on the phone' as a medium is по телефо́ну; на телефо́не means physically on the device.

✅ Поговори́м по телефо́ну.

Let's talk on the phone. — по + dative for the channel.

❌ У меня́ экза́мен в фи́зике.

Wrong — the subject of an exam takes по + dative, not в: экза́мен по фи́зике.

✅ У меня́ экза́мен по фи́зике.

I have a physics exam. — экза́мен по + dative.

❌ По понеде́льник я хожу́ в зал.

Wrong for a routine — 'on Mondays' needs the dative PLURAL: по понеде́льникам. A single Monday would be в понеде́льник.

✅ По понеде́льникам я хожу́ в зал.

On Mondays I go to the gym. — по + dative plural.

❌ Я взял зо́нтик с оши́бкой.

Wrong — 'by mistake' is the fixed по оши́бке, not с оши́бкой.

✅ Я взял зо́нтик по оши́бке.

I took the umbrella by mistake. — по + dative for accidental cause.

Key Takeaways

По almost always takes the dative. Default to it.
Its core senses: motion along/over (по у́лице, по па́рку), medium (по телефо́ну, по телеви́зору), criterion (по пла́ну, по мне́нию, по зако́ну), subject/field (экза́мен по фи́зике, уче́бник по фи́зике), recurring time (по понеде́льникам, по утра́м), distribution (по одному́), and accidental cause (по оши́бке).
Recurring days = по + dative plural (по понеде́льникам); a single day = в + accusative (в понеде́льник).
A rarer по + accusative means "up to and including" (с пе́рвого по пя́тое) — it includes the limit, unlike до.
Don't translate the English preposition; recognize the relationship and reach for по + the dative.

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