Können expresses ability or possibility — it means "can" or "to be able to." Dürfen expresses permission — it means "may" or "to be allowed to." The easiest way to remember the difference between können and dürfen: können = what you're able to do. Dürfen = what you're allowed to do.
Both können and dürfen are German modal verbs, and they follow the same sentence structure. But they have very different meanings — and mixing them up changes what your sentence actually says. This article explains exactly when to use each one, shows you side-by-side examples, covers the most common mistakes, and gives you a quiz to practice.
Können vs. Dürfen: The Key Differences
| Criterion | Können | Dürfen |
|---|---|---|
| Word class | Modal verb | Modal verb |
| Core meaning | Ability, possibility | Permission, prohibition |
| English equivalent | can / to be able to | may / to be allowed to |
| Sentence structure | Position 2 + infinitive at end | Position 2 + infinitive at end |
| Register | Neutral (formal + informal) | Slightly more formal |
| Negation | nicht können = to not be able to | nicht dürfen = must not |
| Interchangeable? | Can replace dürfen in casual speech | Cannot replace können for ability |
What Does "Können" Mean and How Is It Used?
Können means "can" or "to be able to." It expresses that someone has the ability, skill, or possibility to do something. When you use können, you're answering the question: "Am I able to do this?"
Like all modal verbs, können takes position 2 in main clauses, and the main verb goes to the end in its infinitive form. This is standard German word order for modal verbs.
Use können for:
1. Ability or skill — something you've learned or are physically able to do:
Ich kann gut schwimmen.
I can swim well.
Mein Bruder kann fünf Sprachen sprechen.
My brother can speak five languages.
2. Possibility — something that might happen or is feasible:
Es kann morgen regnen.
It could rain tomorrow.
Wir können später darüber reden.
We can talk about it later.
3. Polite requests (Konjunktiv II: könnte) — a softer, more polite way to ask:
Könnten Sie mir bitte helfen?
Could you please help me?
Conjugation of können in the present tense:
| Pronoun | Können |
| ich | kann |
| du | kannst |
| er/sie/es | kann |
| wir | können |
| ihr | könnt |
| sie/Sie | können |
Notice the vowel change: können → kann in the singular (ich, du, er/sie/es). This is typical for German modal verbs.
Conjugation of können in the simple past (Präteritum):
Modal verbs are one of the few verb types where the Präteritum is commonly used in spoken German — even in everyday conversation. While most verbs use the Perfekt in speech, Germans regularly say "Ich konnte nicht kommen" rather than "Ich habe nicht kommen können."
| Pronoun | Können (Präteritum) |
| ich | konnte |
| du | konntest |
| er/sie/es | konnte |
| wir | konnten |
| ihr | konntet |
| sie/Sie | konnten |
Notice: the Umlaut (ö) disappears in the Präteritum. Können → konnte.
What Does "Dürfen" Mean and How Is It Used?
Dürfen means "may" or "to be allowed to." It expresses that someone has permission to do something — or, when negated, that something is forbidden. When you use dürfen, you're answering the question: "Am I allowed to do this?"
The sentence structure is identical to können: conjugated modal in position 2, infinitive at the end.
Use dürfen for:
1. Permission — someone (a parent, teacher, boss, law) allows something:
Du darfst heute länger aufbleiben.
You're allowed to stay up late today.
Darf ich hier sitzen?
May I sit here?
2. Prohibition (nicht dürfen) — a rule, law, or authority forbids something:
Im Museum darf man nicht fotografieren.
You must not take photos in the museum.
Kinder unter 16 dürfen diesen Film nicht sehen.
Children under 16 are not allowed to watch this movie.
Important: Nicht dürfen = English "must not" (prohibition). This is NOT the same as nicht müssen ("don't have to"). This is one of the trickiest points for English speakers — more on this in the common mistakes section further down.
If you're also confused about the difference between müssen and sollen, check out the article on müssen vs. sollen.
3. Very polite requests (Konjunktiv II: dürfte) — even more formal than könnte:
Dürfte ich Sie etwas fragen?
Might I ask you something?
4. Careful estimates (B2+, Konjunktiv II: dürfte) — expressing high probability:
Er dürfte etwa 80 Jahre alt sein.
He's probably around 80 years old.
This use is more advanced and mostly appears in written German or formal speech.
Conjugation of dürfen in the present tense:
| Pronoun | Dürfen |
| ich | darf |
| du | darfst |
| er/sie/es | darf |
| wir | dürfen |
| ihr | dürft |
| sie/Sie | dürfen |
Same pattern as können: vowel change in the singular (dürfen → darf).
Conjugation of dürfen in the simple past (Präteritum):
| Pronoun | Dürfen (Präteritum) |
| ich | durfte |
| du | durftest |
| er/sie/es | durfte |
| wir | durften |
| ihr | durftet |
| sie/Sie | durften |
Same pattern again: the Umlaut (ü) disappears. Dürfen → durfte.
Können vs. Dürfen: Side-by-Side Comparison
The best way to see the difference between können and dürfen is to compare them with the same topic. Look at how the meaning changes depending on which verb you use:
Pair 1 — Swimming
Ich kann gut schwimmen.
I can swim well. → I have the skill.
Ich darf hier schwimmen.
I may swim here. → I have permission.
Pair 2 — Driving
Mein Sohn kann schon Auto fahren.
My son can already drive a car. → He learned how to do it.
Mein Sohn darf schon Auto fahren.
My son is allowed to drive a car already. → He's old enough / has a license.
Pair 3 — Coming to a party
Ich kann leider nicht kommen.
I unfortunately can't come. → I'm not able to (busy, sick, etc.).
Ich darf leider nicht kommen.
I'm unfortunately not allowed to come. → Someone (parents, boss) won't let me.
Pair 4 — Taking photos
Ich kann mit diesem Handy gute Fotos machen.
I can take good photos with this phone. → The phone is capable of it.
Ich darf hier keine Fotos machen.
I'm not allowed to take photos here. → It's forbidden.
Notice the pattern: können is always about your ability or circumstances, while dürfen is always about rules, laws, or someone else's permission.
When Can You Only Use Können or Only Dürfen?
Sometimes the two verbs are not interchangeable at all. Here are situations where only one is correct:
Only können works:
Meine Großmutter kann fünf Sprachen sprechen.
My grandmother can speak five languages. → This is a skill. Nobody gives you "permission" to speak a language.
Flugzeuge können fliegen, aber Menschen nicht.
Airplanes can fly, but humans can't. → This is an inherent ability. Permission is irrelevant.
Only dürfen works:
Im Museum darf man nicht fotografieren.
You must not take photos in the museum. → This is a rule. Using kann here would mean "it's physically impossible," which isn't the point.
Kinder unter 16 dürfen diesen Film nicht sehen.
Children under 16 are not allowed to watch this movie. → This is a legal restriction, not a physical inability.
Can "Können" Replace "Dürfen" in Spoken German?
Yes — and it happens all the time. Just like English speakers say "Can I…?" instead of "May I…?", German speakers often use können where dürfen would be technically more precise.
Kann ich ein Eis haben? (casual — very common)
Can I have an ice cream?
Darf ich ein Eis haben? (grammatically precise)
May I have an ice cream?
In everyday conversation among friends and family, both are perfectly fine. But in formal situations, exams, or when speaking to authority figures, dürfen is the better choice.
There's a classic German teacher joke that perfectly captures this distinction:
Student: "Kann ich auf die Toilette gehen?"
Teacher: "Ich weiß nicht, ob du das kannst, aber du darfst es."
"I don't know whether you can (= are physically able to), but you may (= have permission)."
Important: This overlap only works in one direction. Können can sometimes replace dürfen for permission, but dürfen can never replace können for ability. You cannot say "Ich darf gut schwimmen" — that makes no sense in German.
Common Mistakes With Können and Dürfen
These are the mistakes I see most often with my students. Pay close attention to mistakes 1 and 3 — they're the ones English speakers struggle with most.
Mistake 1: Using können for prohibitions
❌ Im Flugzeug kann man nicht rauchen.
✅ Im Flugzeug darf man nicht rauchen.
Smoking on a plane is forbidden (prohibition), not physically impossible. You technically could light a cigarette — you just aren't allowed to. English speakers make this mistake because "You can't smoke here" usually implies prohibition in English, but in German you need dürfen for that meaning.
Mistake 2: Using dürfen for abilities
❌ Meine Schwester darf sehr gut kochen.
✅ Meine Schwester kann sehr gut kochen.
Cooking well is a skill, not a permission. Nobody grants you permission to cook well — you either have the ability or you don't.
Mistake 3: Confusing nicht dürfen with nicht müssen
❌ Du musst hier nicht parken! (intended: "You must not park here!")
✅ Du darfst hier nicht parken!
This is a critical mistake. Nicht müssen = "don't have to" (no obligation). Nicht dürfen = "must not" (prohibition). Saying "Du musst hier nicht parken" actually means "You don't have to park here" — the opposite of what you intended. For more on how müssen works compared to sollen, see our guide on müssen vs. sollen.
Mistake 4: Using dürfen when können sounds more natural
❌ Darf ich das Fenster aufmachen? (asking a colleague casually)
✅ Kann ich das Fenster aufmachen?
Both sentences are grammatically correct. But in casual, everyday situations — like asking a colleague or a friend — können sounds more natural and relaxed. Dürfen would sound a bit stiff here, as if you need official permission. Save dürfen for genuinely formal situations, or when there's a real authority dynamic (e.g., asking a teacher, a police officer, or a boss in a formal meeting).
Mistake 5: Translating "must not" as nicht können
❌ Du kannst das nicht machen! (intended: "You must not do that!")
✅ Du darfst das nicht machen!
"Du kannst das nicht machen" means "You can't do that" (= you're unable to). If you mean it's forbidden, use dürfen. In English, "You can't do that!" often implies prohibition — but in German, you need dürfen to express that clearly. For more on how negation works in German, check out the full guide.
How to Remember the Difference Between Können and Dürfen
💡 Quick Rule: The "Skill vs. Rule" Test
Können = SKILL → "I have the ability to do it."
Dürfen = RULE → "A rule or person says I may."
Ask yourself: "Is this about what I CAN do, or what I MAY do?"
💡 The Superman vs. Security Guard Analogy
Können = Superman → He has the power/ability to fly through the wall.
Dürfen = Security Guard → He decides who is allowed to walk through the door.
If it's about power, use können. If it's about permission, use dürfen.
💡 The Two Doors Test
Door 1 (können): The door is physically locked or too heavy. You need ability to open it.
→ "Ich kann die Tür nicht öffnen." (I can't open the door.)
Door 2 (dürfen): The door is easy to open, but there's a "NO ENTRY" sign. You need permission.
→ "Ich darf nicht durch die Tür gehen." (I'm not allowed to go through the door.)
Quiz: Können or Dürfen?
Test yourself with these 7 questions. The questions are in German — the explanations are in English.
1. _____ du Klavier spielen?
a) Kannst
b) Darfst
Show answer
Answer: a) Kannst — This is about ability/skill: "Can you play the piano?" Nobody needs to give you permission to play an instrument.
2. Im Kino _____ man nicht telefonieren.
a) kann
b) darf
Show answer
Answer: b) darf — This is a rule: you're not allowed to make calls in the cinema. It's a prohibition, not a physical inability.
3. Mama, _____ ich ein Eis haben?
a) kann
b) darf
Show answer
Answer: b) darf — The child is asking for permission from a parent. While "Kann ich ein Eis haben?" is common in casual speech, darf is the grammatically precise choice since the child is asking whether they're allowed to have ice cream.
4. Mein Opa _____ früher sehr schnell laufen, aber jetzt nicht mehr.
a) durfte
b) konnte
Show answer
Answer: b) konnte — This is about a past ability: the grandfather was able to run fast. No permission is involved. (This uses the Präteritum form of können.)
5. Im Unterricht _____ die Schüler ihre Handys nicht benutzen.
a) können
b) dürfen
Show answer
Answer: b) dürfen — This is a school rule: students are not allowed to use their phones. The teacher or school sets this prohibition.
6. Sie hat nur Russisch gelernt, aber sie _____ auch ein bisschen Polnisch verstehen, weil die Sprachen ähnlich sind.
a) kann
b) darf
Show answer
Answer: a) kann — Understanding a related language is an ability that comes from linguistic similarity — not a permission. Nobody "allows" her to understand Polish; she simply is able to because the languages are similar.
7. In Deutschland _____ man ab 16 Bier trinken, aber Schnaps _____ man erst ab 18 trinken.
a) darf / darf
b) kann / kann
c) darf / kann
d) kann / darf
Show answer
Answer: a) darf / darf — Both blanks refer to legal permission: what the law allows at which age. Ability is not relevant here — it's purely about what you're allowed to do.
Frequently Asked Questions
What is the difference between können and dürfen in German?
Können expresses ability or possibility ("can" / "to be able to"), while dürfen expresses permission ("may" / "to be allowed to"). Können tells you what you're able to do; dürfen tells you what you're allowed to do. Both are modal verbs and follow the same sentence structure.
Can I use können instead of dürfen in German?
In casual spoken German, yes — können often replaces dürfen when asking for permission, just like English speakers say "can I?" instead of "may I?" However, in formal situations, exams, and written German, dürfen is the correct and expected choice for permission. The reverse does not work: dürfen can never replace können for ability.
How do you say "must not" in German?
"Must not" is translated as nicht dürfen, NOT nicht müssen. For example: "Du darfst hier nicht rauchen" (You must not smoke here). Nicht müssen means "don't have to" — a completely different meaning. This is one of the most common mistakes English speakers make with German modal verbs.
Are können and dürfen interchangeable?
Only partially. Können can replace dürfen in casual contexts when asking for permission ("Kann ich rein?" instead of "Darf ich rein?"). But dürfen can never replace können when expressing ability. You can say "Kann ich dir helfen?" (informal) or "Darf ich Ihnen helfen?" (formal), but you cannot say "Ich darf gut schwimmen" — only "Ich kann gut schwimmen."
How do you conjugate können and dürfen?
Both are irregular modal verbs with a vowel change in the singular. Können: ich kann, du kannst, er/sie/es kann, wir können, ihr könnt, sie/Sie können. Dürfen: ich darf, du darfst, er/sie/es darf, wir dürfen, ihr dürft, sie/Sie dürfen. In the simple past (Präteritum), können becomes konnte and dürfen becomes durfte — the Umlaut disappears in both cases.
Related Grammar Topics
If you found this article helpful, these related topics are worth a look:
- German Modal Verbs — Full Guide — All six modal verbs (können, dürfen, müssen, sollen, wollen, mögen) explained with conjugation tables and examples.
- Müssen vs. Sollen — Another tricky modal verb pair: "must" vs. "should."
- German Word Order & Sentence Structure — Understand where modal verbs sit in the sentence and why the infinitive goes to the end.
- Negation: Nicht and Kein — Essential for understanding nicht dürfen vs. nicht müssen.
- Passive With Modal Verbs — How können and dürfen work in passive constructions.
