Knowing and Being Able: Знать, Уметь, Мочь | Russian Grammar

English packs an enormous amount into two little words: know and can. "I know the answer," "I know how to drive," "I can drive you home" — three quite different ideas, two English verbs. Russian draws sharper lines. It uses знать for knowing facts and information, уме́ть for knowing how to do something (a learned skill), and мочь for being able to do something in a given situation. Picking the wrong one is not a small error — \зна́ю пла́вать* ("I know swim") is simply not Russian. This page sorts the three apart and adds a warning about what happens when знать goes perfective.

знать — knowing facts, information, people

Знать means "to know" in the sense of having information, facts, or acquaintance in your head. You знать an answer, a fact, an address, a person, a language as a stored body of knowledge. It is a regular first-conjugation verb (зна́ю, зна́ешь, зна́ет, зна́ем, зна́ете, зна́ют) and very often introduces a clause: Я зна́ю, что... / Я не зна́ю, где....

Я зна́ю отве́т на э́тот вопро́с.

I know the answer to this question. — знать + a fact.

Ты зна́ешь Анну из сосе́днего отде́ла?

Do you know Anna from the next department? — знать + a person (acquaintance).

Я не зна́ю, где он сейча́с живёт.

I don't know where he lives now. — знать introducing a clause.

A crucial fact: знать never means "know how to." It is knowledge that, not knowledge how. You cannot say \Я зна́ю пла́вать* for "I know how to swim" — Russian hears that as ungrammatical. For skills you need уме́ть.

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Use знать only for knowledge you could state, point to, or recall — a fact, a name, a piece of information, a person you've met. The moment the idea is "know how to do something," switch to уме́ть. знать takes a noun or a clause; it never takes another verb in the infinitive.

уме́ть — knowing how to (a learned skill)

Уме́ть means "to be able to" in the sense of having a learned skill — knowing how to do something because you acquired the ability. It is followed by an infinitive and a regular first-conjugation verb (уме́ю, уме́ешь, уме́ет, уме́ем, уме́ете, уме́ют). Swimming, driving, cooking, reading a language — these are уме́ть, because they are skills you learned.

Я уме́ю пла́вать с пяти́ лет.

I've known how to swim since I was five. — уме́ть + infinitive: a learned skill.

Ты уме́ешь води́ть маши́ну?

Do you know how to drive? — уме́ть, ability acquired by learning.

Она́ уме́ет чита́ть по-ру́сски, но говори́т пло́хо.

She can read Russian but speaks it badly. — уме́ть = have the skill.

This is where English "I can" is misleading. "I can swim" = я уме́ю пла́вать (a skill), not я могу́ пла́вать. English uses "can" for skills; Russian insists on уме́ть.

мочь — being able to in a situation

Мочь means "to be able to / can" in the sense of a possibility, circumstance, or permission at a particular moment — whether something is feasible right now, not whether you possess a standing skill. It is followed by an infinitive but conjugates irregularly, with a к/ж alternation and a stress shift:

Person	мочь
я	могу́
ты	мо́жешь
он / она́	мо́жет
мы	мо́жем
вы	мо́жете
они́	мо́гут

Use мочь for "I'm able to (in this situation)," "I'm free to," "circumstances allow it," "I have permission."

Я могу́ помо́чь тебе́ с перее́здом в суббо́ту.

I can help you with the move on Saturday. — могу́: it's possible / I'm available, a circumstance.

Сего́дня я не могу́ прийти́ — я бо́лен.

I can't come today — I'm ill. — не могу́: circumstances prevent it, not a lack of skill.

Не могу́ откры́ть э́ту дверь, её заело́.

I can't get this door open, it's stuck. — могу́: physical possibility in the moment.

уме́ть vs мочь: skill vs circumstance

This is the contrast to nail. Уме́ть = "I have learned how" (a standing ability); мочь = "I am able to right now" (a momentary possibility). The same activity can take either, with different meaning:

Я уме́ю пла́вать, но сейча́с не могу́ — я повреди́л но́гу.

I know how to swim, but right now I can't — I've hurt my leg. — уме́ть (skill) vs мочь (current possibility), in one sentence.

So "Can you swim?" splits in two: Ты уме́ешь пла́вать? asks whether you ever learned; Ты мо́жешь сейча́с пла́вать? asks whether you're allowed/able to swim at this moment (perhaps the pool is open, perhaps your injury has healed). English "can" hides this distinction entirely.

"Know a language": знать or уме́ть, not мочь

Languages straddle the line, and Russian lets you frame them two ways. To say you know a language as a body of knowledge, use знать: Я зна́ю ру́сский. To stress the skill of using it, use уме́ть говори́ть: Я уме́ю говори́ть по-ру́сски. Both are correct; choose by emphasis. What you cannot do is use мочь — \Я могу́ ру́сский* is wrong.

Я зна́ю ру́сский язы́к, но ре́дко на нём говорю́.

I know Russian, but I rarely speak it. — знать = the language as knowledge.

Она́ уме́ет говори́ть на трёх языка́х.

She can speak three languages. — уме́ть говори́ть = the skill of speaking.

узна́ть — when знать goes perfective, the meaning shifts

Here is the trap that catches intermediate learners. Знать is imperfective, and you might expect its perfective to mean "come to know." It does — but in two specific senses that English splits off as different verbs: узна́ть means "find out / learn (a piece of news)" and "recognize." It is not a clean process/result pair with знать; it is a meaning shift.

Я то́лько что узна́л но́вость — они́ пожени́лись!

I just found out the news — they got married! — узна́ть = find out.

Извини́, я тебя́ не узна́л — ты так измени́лся!

Sorry, I didn't recognize you — you've changed so much! — узна́ть = recognize.

So знать (impf.) is the static "have knowledge," while узна́ть (pf.) is the dynamic "acquire the knowledge / identify someone." Do not treat them as the same verb in two aspects the way you would чита́ть / прочита́ть.

A full disambiguation set

Я зна́ю пра́вила игры́.

I know the rules of the game. — знать + facts.

Я уме́ю игра́ть в ша́хматы.

I know how to play chess. — уме́ть + skill.

Я могу́ сыгра́ть с тобо́й сейча́с, у меня́ есть вре́мя.

I can play with you now, I have time. — мочь + current possibility.

The deeper treatment of мочь vs уме́ть, including their past and future forms, is on the modality: мочь / уме́ть page; necessity verbs like до́лжен and на́до are covered on the obligation page.

Common Mistakes

❌ Я зна́ю пла́вать.

Wrong — знать never takes an infinitive and never means 'know how.' Use уме́ть for a skill.

✅ Я уме́ю пла́вать.

I know how to swim.

❌ Я могу́ води́ть маши́ну (meaning 'I have the skill').

Wrong if you mean the learned skill — that's уме́ю. Могу́ води́ть would mean 'I'm able to drive right now (circumstances permit).'

✅ Я уме́ю води́ть маши́ну.

I know how to drive.

❌ Я могу́ ру́сский язы́к.

Wrong — мочь needs an infinitive and isn't used for knowing a language. Use зна́ю ру́сский or уме́ю говори́ть по-ру́сски.

✅ Я зна́ю ру́сский язы́к.

I know Russian.

❌ Я мо́жу прийти́ за́втра.

Wrong — the я-form of мочь is могу́, not *мо́жу.

✅ Я могу́ прийти́ за́втра.

I can come tomorrow.

❌ Вчера́ я знал но́вость о сва́дьбе.

Wrong for 'I found out' — the static знал means 'I knew (already).' To 'find out' use the perfective узна́л.

✅ Вчера́ я узна́л но́вость о сва́дьбе.

Yesterday I found out the news about the wedding.

Key Takeaways

знать = know facts, information, people, a language as knowledge (зна́ю отве́т, зна́ю Анну, зна́ю ру́сский). It takes a noun or a clause, never an infinitive, and never means "know how."
уме́ть = know how to — a learned skill (уме́ю пла́вать, води́ть, гото́вить). Takes an infinitive.
мочь = be able to in a situation — possibility, circumstance, permission (могу́ прийти́, не могу́ откры́ть дверь). Takes an infinitive; conjugates могу́ / мо́жешь / мо́гут.
English "can" is split: "I can swim" = уме́ю (skill), "I can come" = могу́ (possibility).
A language is зна́ю (knowledge) or уме́ю говори́ть (skill), never мочь.
The perfective узна́ть shifts meaning to "find out" and "recognize" — знать / узна́ть is not a plain aspect pair but a meaning change.

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