German modal verbs: können, müssen, dürfen, sollen, wollen, mögen

Six modal verbs, plus möchte

A modal verb changes the meaning of another verb. Ich arbeite means “I work”; ich muss arbeiten means “I have to work”, ich kann arbeiten “I can work” and ich will arbeiten “I want to work”. The action is the same, but the modal tells you whether it is possible, necessary, allowed, expected or wanted.

German grammars list six modal verbs. A seventh form, möchte, is so common that most courses teach it as a verb of its own from the first lessons. Strictly speaking it is the Konjunktiv II of mögen, a polite “would like”, but in everyday German it works like a separate modal with its own present tense.

Present tense: the irregular singular

Modal verbs are irregular in the singular, and they all follow the same pattern. First, the ich and er/sie/es forms are identical and have no ending: ich kann, er kann; ich muss, sie muss. Second, most modals change their vowel in the singular: können becomes kann, müssen becomes muss, dürfen becomes darf, wollen becomes will and mögen becomes mag. Only sollen keeps its vowel: ich soll.

The plural is regular. Wir and sie/Sie use the infinitive (wir können, sie müssen) and ihr adds -t to the stem with the vowel of the infinitive (ihr könnt, ihr dürft). So once you know the singular, you know the whole verb.

The infinitive goes to the end

In a main clause, the conjugated modal sits in second position, as every conjugated verb does in German. The second verb goes to the very end of the clause, in the infinitive. Everything else, objects, times and places, fits in between, which is why the two verbs often end up far apart.

Two details catch English speakers out. There is no zu before the infinitive after a modal: ich muss arbeiten, never ich muss zu arbeiten, even though English says “have to work”. And in a subordinate clause, introduced by words like weil, dass or wenn, the modal itself moves to the very end, after the infinitive: weil ich arbeiten muss.

When the meaning is clear, the infinitive can disappear. Ich muss jetzt nach Hause means “I have to go home now”, with gehen understood. Ich kann Deutsch means “I speak German”, and Ich mag Kaffee simply means “I like coffee”. These short forms are very common in speech.

The pairs learners mix up

Each modal has a clear core meaning, but some pairs overlap with one English word, or split one English word in two. These are the differences that cause most mistakes, even at B1 and B2.

Müssen or sollen?

Both can translate as “have to” or “should”, but they come from different places. Müssen is a necessity: the situation, a rule or the speaker's own judgment makes it unavoidable. Sollen is what someone else wants you to do: an instruction, a request or advice from another person. If you can add “they told me to”, sollen is usually the right choice.

Nicht müssen or nicht dürfen?

This is the classic trap. English “must not” is a prohibition, but German nicht müssen only means that something is not necessary: “don't have to”. To forbid something, German uses nicht dürfen. A sign that says Hier darf man nicht rauchen means you are not allowed to smoke; du musst nicht rauchen would mean that nobody is forcing you to.

Wollen or möchte?

Both express a wish, and the difference is mostly tone. Wollen is direct and firm: ich will is a clear “I want”. Möchte is softer and polite, like “I would like”. In a café or a shop, ich möchte einen Kaffee is the normal way to order; ich will einen Kaffee sounds like a demand. Between friends, or when you talk about plans, wollen is perfectly natural: wir wollen im Sommer heiraten.

Mögen or möchte?

They come from the same verb, but they say different things. Ich mag Tee is a general fact about your taste: I like tea. Ich möchte einen Tee is a wish for right now: I would like a tea. A waiter asks Was möchten Sie trinken?, never Was mögen Sie trinken?, because the question is about this moment, not about your preferences in general.

Können or dürfen?

Können is about ability or possibility, dürfen about permission. In everyday speech, kann ich…? is often used to ask for permission too, just as English uses “can I…?”. Darf ich…? is the more polite choice, and the safe one with people you address as Sie: Darf ich Sie etwas fragen?

Nicht müssen means you don’t have to. Nicht dürfen means you must not.

The past: konnte, musste, durfte

With most verbs, spoken German uses the perfect for the past: ich habe gearbeitet. Modal verbs are different. Germans normally use the simple past (Präteritum) with modals, in speech as well as in writing: ich musste arbeiten, I had to work. The perfect forms exist, but they are rarer and more awkward, so the simple past is the form to learn first.

The simple past is easy to build. Take the stem, drop the umlaut, and add -te with the usual past endings: können becomes konnte, müssen becomes musste, dürfen becomes durfte. Mögen changes its consonant too and becomes mochte. Again, ich and er/sie/es are identical: ich konnte, sie konnte.

The perfect: the double infinitive

At B2 you will meet the perfect of modal verbs, and it has a famous quirk. When a modal is used with another verb, its participle is not gemusst or gekonnt but the infinitive. The result is two infinitives at the end of the clause, the main verb first and the modal last: ich habe arbeiten müssen. Grammars call this the double infinitive, or Ersatzinfinitiv.

Two rules go with it. The auxiliary is always haben, even when the main verb normally takes sein: ich bin gegangen, but ich habe gehen müssen. And in a subordinate clause the auxiliary does not go to the very end; it stands before the two infinitives: dass er hat warten müssen. This is one of the few exceptions to verb-final word order.

Without a second verb, the modal takes a normal participle: Ich habe das nicht gekonnt, I couldn't do it; Er hat es so gewollt, he wanted it that way. In daily life, most Germans avoid the double infinitive and simply say ich musste arbeiten, but you need to recognize it in texts and use it in exams.

Konjunktiv II: the polite modals

German uses the Konjunktiv II, its subjunctive, to make requests and suggestions softer. With modals it is very simple: take the simple past and add the umlaut back where the infinitive has one. Konnte becomes könnte, musste becomes müsste, durfte becomes dürfte and mochte becomes möchte. Sollte and wollte do not change, because sollen and wollen have no umlaut.

In daily life, könnten Sie…? is the standard polite request, and du solltest… is the normal way to give advice: it is softer than du musst and less bossy than an order. Dürfte also expresses a careful guess: Das dürfte reichen, that should be enough.

Modals that express a guess

Modals also tell you how sure the speaker is. Er muss krank sein can mean “he must be ill”: the speaker is fairly certain. Er könnte krank sein means “he might be ill”, and er dürfte krank sein “he is probably ill”. Sollen and wollen have a special use here too: Das Restaurant soll sehr gut sein means “the restaurant is said to be very good”, passing on what others say, and Er will das Geld nicht gesehen haben means “he claims not to have seen the money”.

Common mistakes

These mistakes are typical for English speakers, and each one breaks a rule from this article.

How to make modals automatic

Modals are worth practicing early, because you need them in almost every real situation: ordering, asking for help, making plans, explaining what you have to do. Start with the present tense and the word order, then add the simple past, and keep the double infinitive for when your German is solid.

Learn each modal in full sentences rather than as a single word. Ich muss morgen arbeiten teaches you the meaning, the form and the word order at once. Say the sentences aloud, then change the person and the tense: ich muss, er muss, wir mussten. A few minutes like this every day does more than an hour once a week.

Pay special attention to the pairs that do not match English: nicht müssen and nicht dürfen, wollen and möchte, will and werde. Write your own example for each, about your own life, and they will stick much better than examples from a book.

At Alimun, exercises with instant feedback show you right away when a modal is in the wrong form or the infinitive is in the wrong place, and your teacher corrects your homework. In live classes with a teacher and the same small group, you use the modals every week to make plans, give advice and ask politely, which is exactly how they become automatic.

Questions people ask

Sources: Duden: müssen, Duden: dürfen, Duden: sollen, Duden: mögen, Dartmouth College: German modal verbs, University of Texas, Grimm Grammar: modal verbs in the past.