können: Ability, Possibility, Permission | German Grammar

können is the German "can." It covers ability ("I can swim"), possibility ("that can happen"), and — informally — permission ("can I go?"). It is the modal you will reach for most often, and it hides one beautifully economical trap: the difference between konnte ("was able") and könnte ("could / would be able") is a single umlaut that flips a fact into a polite hypothetical.

Conjugation

Present — note the singular vowel a and the missing -t on er (see the modal overview):

Person	Present	Präteritum	Konjunktiv II
ich	kann	konnte	könnte
du	kannst	konntest	könntest
er/sie/es	kann	konnte	könnte
wir	können	konnten	könnten
ihr	könnt	konntet	könntet
sie/Sie	können	konnten	könnten

Perfekt: two forms, depending on whether a main verb is present.

With a main verb (the usual case), German uses the double infinitive: Ich habe nicht kommen können "I couldn't come."
Standing alone, with no main verb, it uses the participle gekonnt: Das habe ich noch nie gekonnt "I've never been able to do that."

See modal Perfekt and the double infinitive.

Meaning 1: ability — learned and physical

The most basic use is being able to do something, whether through skill or physical capacity.

Ich kann ein bisschen Klavier spielen.

I can play the piano a little. (learned ability; informal)

Mit dem gebrochenen Bein kann sie nicht laufen.

With her broken leg she can't walk. (physical ability)

A special case: for a language, German uses können with the language name and no main verb — you do not say sprechen können unless you specifically mean the act of speaking.

Kannst du Deutsch?

Can you speak German? / Do you know German? (informal)

This is a real false-friend zone, because English "know" tempts learners toward kennen or wissen. German keeps them distinct: können a language = have the skill; kennen a thing/person = be acquainted with it; wissen a fact = know that something is the case. See kennen, wissen, können.

Meaning 2: possibility

können also expresses that something is possible — that it can (i.e. may well) happen or be the case.

Das kann sein.

That's possible. / That may be. (informal)

Es kann sein, dass der Zug Verspätung hat.

It's possible the train is delayed.

Bei diesem Wetter kann alles passieren.

In this weather anything can happen.

Meaning 3: informal permission (overlapping with dürfen)

In careful or formal German, permission belongs to dürfen: Darf ich gehen? "Am I allowed to go?" But in everyday speech, Germans constantly use können for permission, exactly as English uses "can" rather than "may."

Kann ich kurz auf die Toilette?

Can I quickly go to the bathroom? (informal, asking permission)

Du kannst mein Auto nehmen, kein Problem.

You can take my car, no problem. (informal: giving permission)

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For permission, können is fine in conversation but dürfen is the precise, polite, and "correct" choice — especially in formal contexts, with strangers, or when a real rule is at stake. Darf ich rauchen? ("Am I allowed to smoke?") respects the rule; Kann ich rauchen? literally asks whether you are physically able to.

Standalone können (no infinitive)

Like all German modals, können can stand on its own when the main verb is obvious or when it means "manage / cope."

Ich kann nicht mehr.

I can't (go on) anymore. / I'm worn out. (informal)

Sie kann das einfach.

She's just good at it. / It comes easily to her. (informal)

könnte vs konnte — the umlaut that changes everything

This is the high-value point. The Präteritum konnte states a past fact: was able to. The Konjunktiv II könnte is the polite, tentative could / would be able to — used for requests, suggestions, and hypotheticals. They differ only by the umlaut on the o.

Früher konnte ich die ganze Nacht durchtanzen.

I used to be able to dance all night long. (past fact — konnte)

Könntest du mir bitte helfen?

Could you please help me? (tentative — könnte; polite request)

Wir könnten ja ins Kino gehen.

We could go to the movies, you know. (suggestion — könnte; informal suggestion)

English blurs this: "could" serves both the past of "can" ("I could swim as a child") and the conditional ("Could you help me?"). German forces you to choose the umlaut. If you mean a past ability, write konnte; if you mean a soft "could," write könnte. More in Konjunktiv II of modals.

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Mnemonic: the umlaut "lifts" the verb out of reality into the polite/hypothetical. konnte is grounded in the past; könnte floats in the conditional. Two dots, one big difference.

Common Mistakes

❌ Ich kenne Deutsch sprechen.

Wrong verb: kennen is 'to be acquainted with,' not 'to be able to.' For a skill use können.

✅ Ich kann Deutsch (sprechen).

I can speak German.

❌ Könntest du gestern kommen?

Wrong: könnte is the polite/hypothetical 'could,' not a past tense. For 'were you able to yesterday' use konntest.

✅ Konntest du gestern kommen?

Were you able to come yesterday?

❌ Er kann gut Deutsch sprechen kann.

Wrong: the conjugated modal goes in position 2 only; the bare infinitive sprechen closes the clause.

✅ Er kann gut Deutsch sprechen.

He can speak German well.

❌ Ich habe nicht kommen gekonnt.

Wrong: with a main verb, the Perfekt uses the double infinitive, not the participle gekonnt.

✅ Ich habe nicht kommen können.

I couldn't come. / I wasn't able to come.

❌ Darfst du schwimmen?

Wrong nuance: dürfen asks about permission. For ability, use können. (intended: are you physically able?)

✅ Kannst du schwimmen?

Can you swim? (ability)

Key Takeaways

können covers ability (skill and physical), possibility, and informal permission.
For a language, use können with no main verb: Ich kann Deutsch — not kennen/wissen.
Present singular vowel is a (kann) with no -t on er; plural restores the umlaut (können).
konnte = past fact "was able"; könnte = polite/hypothetical "could." One umlaut decides.
For permission, können is conversational but dürfen is the precise choice.

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