The Konjunktiv Moods

Again: the Konjunktiv I mood is fairly uncommon and you shouldn’t spend too much time on it. At most, it can be mildly helpful to recognize it when reading the newspaper. It's used for reported speech (without quotation marks) in a relatively formal setting: According to a witness, the robbers escaped in a blue van. It’s rarely used in informal settings; in a sentence like My sister says her friends will meet us at the restaurant at 8, you just use the ordinary (indicative) present or future tense.

The endings for the present Konjunktiv I are like those of the strong verb present tense (V.3) with a few extra Es, and with no stem changes: even a strong, mixed or modal verb just takes the normal infinitive stem. Sein is the only irregular verb in the Konjunktiv I (see below).

Past tense statements are formed like the Perfekt, only with haben/sein in the Konjunktiv I instead of the normal present tense. Likewise, the future tenses are formed with werden in the Konjunktiv I.

Konjunktiv I

haben sein werden
singular 1st person ich kaufe I buy habe sei werde
2nd person du kaufest you buy habest seist werdest
3rd person er/sie/es kaufe he/she/it buys habe sei werde
plural 1st person wir kaufen we buy haben seien werden
2nd person ihr kaufet you (pl) buy habet seit werdet
3rd person sie/Sie kaufen they buy haben seien werden
 

You may have noticed that some of the above forms are identical to the normal (indicative) present tense – ich kaufe, for example. In these cases it’s common to use the Konjunktiv II forms instead (coming up next) to avoid confusion.

In practice, the Konjunktiv I is mostly used in the third person. You are most likely to notice it in a news article in the form of sei where you’d expect ist, or habe where you’d expect hat.

The Konjunktiv II mood is much more common than the Konjunktiv I. It’s used to express wishes, desires, speculation, conditionality, and other “unreal” conditions, and it usually translates in English with words like were, would, or could:

If I were rich, I would buy it. Wenn ich reich wäre, würde ich es kaufen.

There are three ways to form the Konjunktiv II:

  1. For weak verbs, it’s the same as the (indicative) Präteritum (given in V.3)
  2. For non-weak verbs (aux., modal, mixed, strong), it’s the simple past stem with an added umlaut and those same –e endings from the Konjunktiv I (above)
  3. BUT for certain strong verbs, the vowel in that past stem is conventionally replaced with a ü; for example, the KII of "helfen" is not hälfen from the past stem half, but rather hülfen

Sounds like a nightmare to learn, right? But you probably don't have to. Because in practice, the only verbs that are always conjugated in the Konjunktiv II are the modal and auxiliary verbs. Once you’ve learned their subjunctive forms, you can just use those forms with the infinitives or participles of other verbs. Notice that sollen and wollen are the only exceptions to rule #2 above, in that they don’t get the umlaut:

  sein haben werden dürfen können mögen müssen sollen wollen
ich wäre hätte würde dürfte könnte möchte müsste sollte wollte
du wärest hättest würdest dürftest könntest möchtest müsstest solltest wolltest
er/sie/es wäre hätte würde dürfte könnte möchte müsste sollte wollte
wir wären hätten würden dürften könnten möchten müssten sollten wollten
ihr wäret hättet würdet dürftet könntet möchtet müsstet solltet wolltet
sie/Sie wären hätten würden dürften könnten möchten müssten sollten wollten

The main one you’ll use is werden, which works like would in English:

Would you help me with this?
Würdest du mir damit helfen?

There are a few strong verbs that are occasionally used in the Konjunktiv II, but as a foreign speaker, you really don’t need to worry about them: just use the werden form for everything except the nine verbs in the table above.

One of the most common forms in that table is möchten (would like), from mögen (to like); it’s used for ordering in restaurants (Ich möchte einen Kaffee) and other polite requests, as well as more general wishes and desires. In fact it’s so common that it’s often introduced, confusingly, as a seventh modal verb independent from mögen. If you’ve learned it that way, then now you know the truth.