A modal verb doesn't tell you what happens — it tells you the circumstances around what happens. Ich gehe is a statement. Ich muss gehen adds necessity. Ich kann gehen adds ability. Ich darf gehen adds permission. The main verb stays the same; the modal changes its meaning entirely.
German has six modal verbs: können, müssen, dürfen, sollen, wollen, mögen. They all share the same structural behaviour and a similar conjugation pattern — but they are irregular in a specific way that needs to be learned.
How Modal Verbs Work
In a sentence with a modal verb, there are always two verbs. The modal verb is conjugated — it agrees with the subject and carries the tense. The main verb stays in the infinitive and moves to the end of the clause.
Ich kann Deutsch sprechen.
I can speak German. (können conjugated as kann; sprechen infinitive at end)
Er muss morgen arbeiten.
He has to work tomorrow.
Sie will ein Buch kaufen.
She wants to buy a book.
The modal sits in position two — the standard verb position. The infinitive always goes to the very end of the clause, no matter how long the sentence.
Conjugation — The Pattern They All Share
Modal verbs are irregular, but they share a consistent pattern: the first and third person singular forms are identical and have no ending, and the vowel in the singular often differs from the infinitive. The plural forms are more regular.
| können | müssen | dürfen | sollen | wollen | mögen | |
|---|---|---|---|---|---|---|
| ich | kann | muss | darf | soll | will | mag |
| du | kannst | musst | darfst | sollst | willst | magst |
| er/sie/es | kann | muss | darf | soll | will | mag |
| wir | können | müssen | dürfen | sollen | wollen | mögen |
| ihr | könnt | müsst | dürft | sollt | wollt | mögt |
| sie/Sie | können | müssen | dürfen | sollen | wollen | mögen |
The key pattern: ich and er/sie/es are always identical, and always have no personal ending. This is unlike all regular German verbs. Ich kann, er kann — no -e, no -t.
Wollen — ich will, not ich wille
Wollen is the most commonly misspelled modal. Ich will means "I want to." It has nothing to do with the English word "will" as a future marker. There is no future meaning in ich will — it expresses desire or intention in the present. A German learner writing ich wille is adding an ending that doesn't belong. A German speaker saying ich will das machen means "I want to do that," not "I will do that."
Können — Ability and Possibility
Können expresses that something is within the subject's capacity — physical ability, learned skill, or general possibility.
Ich kann schwimmen.
I can swim. (ability)
Kannst du Klavier spielen?
Can you play piano?
Hier kann man gut essen.
You can eat well here. / It's possible to eat well here.
Das kann ich nicht verstehen.
I can't understand that.
Müssen — Necessity and Obligation
Müssen expresses that something is necessary — either because of an external rule or an internal compulsion. It corresponds to "must" and "have to."
Ich muss jetzt gehen.
I have to go now.
Du musst mehr schlafen.
You need to sleep more.
Wir müssen um 8 Uhr da sein.
We have to be there at 8 o'clock.
Dürfen — Permission
Dürfen expresses permission — whether something is allowed. It corresponds to "may" and "to be allowed to." It is not about ability (that's können) — it's specifically about permission.
Darf ich hier parken?
Am I allowed to park here? / May I park here?
Hier darf man nicht rauchen.
Smoking is not allowed here.
Kinder dürfen bis 22 Uhr aufbleiben.
Children are allowed to stay up until 10pm.
The Negation Flip: Müssen and Dürfen
This is the most important — and most frequently confused — point about German modal verbs. Negating müssen and dürfen does not produce parallel meanings. They flip.
| German | Meaning |
|---|---|
| Du musst das machen. | You have to do that. (obligation) |
| Du musst das nicht machen. | You don't have to do that. (no obligation) |
| Du darfst das nicht machen. | You must not do that. (prohibition) |
Nicht müssen ≠ nicht dürfen
Du musst nicht = you don't have to (it's not required, but you can if you want). Du darfst nicht = you must not (it is forbidden). These are complete opposites. Confusing them produces serious misunderstandings — telling someone du musst das nicht essen means "you don't have to eat that" (it's fine either way), while du darfst das nicht essen means "you are not allowed to eat that" (prohibition).
Sollen — Instruction and Expectation
Sollen expresses that someone has been told to do something, or that there is an expectation from outside. The instruction or expectation comes from another person, not from the subject themselves. It corresponds to "should," "is supposed to," "has been told to."
Du sollst um 9 Uhr hier sein.
You're supposed to be here at 9. (someone told you)
Er soll den Arzt anrufen.
He's supposed to call the doctor. (he's been told to)
Was soll ich tun?
What am I supposed to do? / What should I do?
Sollen vs. müssen — source of obligation
Müssen comes from necessity or inner compulsion — the situation demands it. Sollen comes from someone else's instruction or expectation. Ich muss gehen — I have to go (there's a reason, a train to catch, a rule). Ich soll gehen — I've been told to go (someone instructed me). In practice: if a parent says it, use sollen. If a fire alarm demands it, use müssen.
Wollen — Intention and Desire
Wollen expresses what the subject wants or intends to do. The desire or intention comes from inside the subject. It corresponds to "want to" and "intend to."
Ich will Architekt werden.
I want to become an architect.
Was willst du heute machen?
What do you want to do today?
Wir wollen nächstes Jahr nach Japan reisen.
We want to travel to Japan next year.
Mögen and Möchten — Liking and Wanting
Mögen in its objective use expresses liking — enjoying or being fond of something. It is most commonly used without an infinitive, directly with a noun.
Ich mag Kaffee.
I like coffee.
Magst du klassische Musik?
Do you like classical music?
Er mag keine Spinnen.
He doesn't like spiders.
Möchten is the Konjunktiv II form of mögen but functions as an independent modal at A2 level. It expresses a polite desire or request — "would like to." It is the standard polite way to express wanting something.
| möchten | |
|---|---|
| ich | möchte |
| du | möchtest |
| er/sie/es | möchte |
| wir | möchten |
| ihr | möchtet |
| sie/Sie | möchten |
Ich möchte einen Kaffee, bitte.
I would like a coffee, please.
Möchtest du mitkommen?
Would you like to come along?
Sie möchte Lehrerin werden.
She would like to become a teacher.
Mögen vs. möchten
Mögen = to like (ongoing feeling). Ich mag Pizza — I like pizza. Möchten = would like (specific, often immediate desire). Ich möchte Pizza bestellen — I would like to order pizza. Möchten has no past tense form in common use — for past "wanted," use wollte (past tense of wollen) instead.
Word Order With Modal Verbs
The rule is consistent across all six modals: the conjugated modal occupies position two, and the infinitive goes to the very end of the clause.
Ich [kann] heute Abend nicht [kommen].
Morgen [muss] sie früh [aufstehen].
[Darf] ich kurz [fragen]?
In a subordinate clause introduced by a conjunction like weil, dass, obwohl, both verbs go to the end — infinitive first, modal second:
Ich weiß, dass er nicht kommen kann.
I know that he can't come. (kommen before kann)
Sie bleibt zu Hause, weil sie arbeiten muss.
She's staying home because she has to work.
Modal Verbs Without an Infinitive
Modal verbs can appear without a main verb infinitive when the meaning is clear from context, or when the infinitive is a motion or activity verb that is commonly omitted in German.
Ich muss jetzt. (= Ich muss jetzt gehen.)
I have to now. / I need to go now.
Kannst du Deutsch? (= Kannst du Deutsch sprechen?)
Do you speak German? / Can you [speak] German?
Ich will nach Hause. (= Ich will nach Hause gehen.)
I want to go home.
This is especially common with verbs of motion (gehen, fahren, kommen) which are dropped when the destination makes them redundant.
Common Traps
Trap 1 — Ich will = I want, not I will
Ich will das machen means "I want to do that." For future in German, use werden or present tense with a time expression. Will is never a future marker in German.
Trap 2 — Musst nicht vs. darfst nicht
Du musst nicht kommen. (You don't have to come — it's optional.)
Du darfst nicht kommen. (You must not come — it's forbidden.)
Trap 3 — Adding an ending to ich/er forms
Ich kann ✓ / Ich kanne ✗
Er muss ✓ / Er musst ✗
Sie will ✓ / Sie willet ✗
Trap 4 — Infinitive in the wrong position
Ich kann nicht verstehen das. ✗
Ich kann das nicht verstehen. ✓ (infinitive at the end)
Trap 5 — Können vs. dürfen for permission
In English, "can" covers both ability and permission. In German they are separate. Asking Kann ich das Fenster öffnen? is grammatically correct but technically asks about ability (are you physically capable?). Darf ich das Fenster öffnen? is the correct form for requesting permission.
Können for permission in speech
That said, using können to ask permission is extremely common in casual spoken German — just as "can I" is standard in English despite the prescriptive preference for "may I." Kann ich kurz stören? is natural speech. Darf ich kurz stören? is more formal. Both are understood and used.
Quick Recap
- Modal verbs modify the main verb. The modal is conjugated in position two; the main verb stays as an infinitive at the end of the clause.
- All modals: ich and er/sie/es forms are identical and have no ending. Singular vowels often differ from the infinitive.
- Können — ability and possibility. Ich kann schwimmen.
- Müssen — necessity and obligation. Ich muss gehen.
- Dürfen — permission. Darf ich fragen?
- Sollen — instruction from outside. Someone told you to. Du sollst anrufen.
- Wollen — intention and desire from inside. You want to. Ich will Arzt werden.
- Mögen — liking. Usually without infinitive. Ich mag Musik.
- Möchten — would like. Polite desire. Ich möchte einen Tee, bitte.
- Critical negation rule: nicht müssen = don't have to (no obligation). nicht dürfen = must not (prohibition). These are opposites.
- In subordinate clauses: infinitive before modal, both at the end. …weil er kommen kann.
- Ich will = I want to. Never a future marker.