Conjugation tips and tricks

In german language we come across 3 types of verbs: schwach (weak), stark (strong irregular), and gemischt (mixed or weak irregular).
Will take them one by one for a better understanding.

Weak (regular) verbs (schwache Verben)

have a predictable pattern when conjugated. Have consistent stems and regular endings, with no stem-vowel changes in any tense.
I will go through every tense with sagen and spielen as examples.

First we need to determine the stem. As you may have noticed, the infinitive in is its unaltered base form typically ends in -en or -n in German language, so the stem will look like this: for sagen is sag- , for spielen is spiel-. Now that we have the stem, lets have some fun with the tenses!

Indicative (Indikativ)

Present tense (Präsens): verbs get the following endings added to the stem: -e, -st, -t, en, -t, -en
Examples: Ich sage / Ich spiele
Du sagst/Du spielst

Simple past (Präteritum): verbs get the following endings added to the stem: -te, -test, -te, -ten, -tet, -ten
Examples : Ich sagte / Ich spielte

Perfect (Perfekt): here we have one of the auxiliary verbs haben or sein in their conjugated indicativ present form + our verb with the past participle (ge- + stem + -t).
Examples: Ich habe gesagt/Ich habe gespielt

Past participle (Plusquamperfekt): here we have one of the auxiliary verbs haben or sein in their conjugated indicative simple past form + our verb with the past participle (ge- + stem + -t).
Examples: Ich hatte gesagt/Ich hatte gespielt

Future (Futur I): here we have auxiliary verb werden in its conjugated indicative present form + our verb at its infinitive form.
Examples: Ich werde sagen/Ich werde spielen

Future (Futur II): here we have auxiliary verb werden in its conjugated present form + our verb at its infinitive form + haben or sein in the infinitive form.
Examples: Ich werde gesagt haben/Ich werde gespielt haben

Subjunctive I (Konjunktiv I)

Present tense (Präsens): present tense konjunktiv I has almost the same conjugation endings as the normal present tense, changes are ar second and third person singular and second person plural: -e, -est, -e, -en, -et, -en.
Examples: Ich sage/Ich spiele
Du sagest/Du spielest

Perfect (Perfekt): here we have one of the auxiliary verbs haben or sein in their conjugated konjunktiv I present form + our verb with the past participle (ge- + stem + -t).
Examples: Ich habe gesagt/Ich habe gespielt

Future (Futur I): here we have auxiliary verb werden in its conjugated konjunktiv I present form + our verb at its infinitive form.
Examples: Ich werde sagen/Ich werde spielen

Future (Futur II): here we have auxiliary verb werden in its conjugated konjunktiv I present form + our verb with the past participle (ge- + stem + -t)+ haben or sein in their infinitive form.
Examples: Ich werde gesagt haben/Ich werde gespielt haben

Subjunctive I (Konjunktiv II)

Simple past (Präteritum): in konjunktiv II for weak verbs we have the same endings added to the stem as in indicative simple: -te, -test, -te, -ten, -tet, -ten
Examples : Ich sagte / Ich spielte

Past participle (Plusquamperfekt): here we have one of the auxiliary verbs haben or sein in their conjugated konjunktiv II präteritum form + our verb with the past participle (ge- + stem + -t).
Examples: Ich hätte gesagt/Ich hätte gespielt

Future (Futur I): here we have auxiliary verb werden in its conjugated konjunktiv II präteritum form + our verb at its infinitive form.
Examples: Ich würde sagen/Ich würde spielen

Future (Futur II): here we have auxiliary verb werden in its conjugated konjunktiv II präteritum form + our verb with the past participle (ge- + stem + -t)+ haben or sein in the infinitive form.
Examples: Ich würde gesagt haben/Ich würde gespielt haben

Strong irregular verbs (stark Verben)

often have unique endings during conjugation, stem-vowel changes in one or more of the tenses, sometimes including the present tense and should be memorized. These verbs use the same endings like modal verbs (are 6 of them and are a special category) in simple past tense, particularly no endings for 1st and 3rd person singular. As for the past participle, ends in -en (Zum Beispiel). More details about the modal verbs can be found in this section here

I will go through every tense with verbs essen and sehen as examples but for full conjugations you will have to visit the common verbs page and strong irregular verbs list can be found here.

Indicative (Indikativ)
Present tense (Präsens): for strong verbs are often vowel changes in the stem.
Examples: Ich esse / Du isst (or du ißt)
Ich sehe/Du siehst

Simple past (Präteritum): follows no regular patern, and uses unique vowel changes
Examples : Ich aß / Du aßest
Ich sah/Du sahst

Perfect (Perfekt): Examples: Ich habe gegessen
Ich habe gesehen

Past participle (Plusquamperfekt): Examples: Ich hatte gegessen
Ich hatte gesehen

Future (Futur I): Examples: Ich werde essen
Ich werde sehen

Future (Futur II): Examples: Ich werde gegessen haben
Ich werde gesehen haben

Konjunktiv I

Present tense (Präsens): Examples: Ich esse/Du essest
Ich sehe/Du sehest

Perfect (Perfekt): Examples: Ich habe gegessen
Ich habe gesehen

Future (Futur I): Examples: Ich werde essen
Ich werde sehen

Future (Futur II): Examples: Ich werde gegessen haben
Ich werde gesehen haben

Konjunktiv II

Simple past (Präteritum): in konjunktiv II the vowels "a", "o", "u" change into „ä“, „ö“, „ü" and an -e must be added to the first and third person singular if is missing.
Examples: Ich äße / Du äßest
Ich sähe / Du sähest

Past participle (Plusquamperfekt): Examples: Ich hätte gegessen
Ich hätte gesehen

Future (Futur I): Examples: Ich würde essen
Ich würde sehen

Future (Futur II): Examples: Ich würde gegessen haben
Ich würde gesehen haben


Note: There are also strong verbs that change like this: helfen (to help) -> half -> hülfe (not hälfe!!!) and any verb that has a stem-change in the present tense is a strong verb.

A list with the strong irregular verbs can be found here

Mixed verbs - weak irregular verbs (gemischt Verben)

combine the elements of both weak and strong verbs, a stem change, as seen in strong verbs, but also use the same past-tense verb endings used with weak verbs. These verbs have the vowels from Infinitive forms changed in their Imperfect and Past Participle forms.
Examples: denken (to think) : dachte, gedacht
nennen (to name) : nannte, genannt
bringen (to bring) : brachte, gebracht
The verbs senden (to send) and wenden (to turn) have two different forms in their past tenses.
Examples: wenden, wendete/wandte, gewendet/gewandt
senden, sendete/sandte, gesendet/gesandt

I will go through every tense with wissen as examples but for full conjugations you will have to visit the common verbs page.

Indicative (Indikativ)
Present tense (Präsens): Examples: Ich weiß/Du weißt

Simple past (Präteritum): Example: Ich wusste (or wußte)/Du wusstest (or wußtest)

Perfect (Perfekt): Example: Ich habe gewusst (or gewußt)

Past participle (Plusquamperfekt): Example: Ich hatte gewusst (or gewußt)

Future (Futur I): Example: Ich werde wissen

Future (Futur II): Example: Ich werde gewusst (or gewußt) haben

Konjunktiv I

Present tense (Präsens): Example: Ich wisse/Du wissest

Perfect (Perfekt): Example: Ich habe gewusst (or gewußt)

Future (Futur I): Example:Ich werde wissen

Future (Futur II): Example: Ich werde gewusst (or gewußt) haben

Konjunktiv II

Simple past (Präteritum): Example:Ich wüsste (or wüßte) / Du wüsstest (or wüßtest)

Past participle (Plusquamperfekt): Example: Ich hätte gewusst (or gewußt)

Future (Futur I): Example: Ich würde wissen

Future (Futur II): Example: Ich würde gewusst (or gewußt) haben

A list with the mixed verbs

In german language, modal verbs are a special category and are 6 of them: können (can), dürfen (may), mögen (like), müssen (must), sollen (should), wollen (want). Most of the times you will find them combined with other verbs in a phrase.
However, when conjugated they follow similar patterns, for example: 1st, 2nd and 3rd form singular is a stem change (except for sollen) while for 1st and 3rd person singular the regular endings are missing.

Rule nr. 1: In the present tense are irregular for 1st, 2nd and 3rd person singular while for plural forms are regular.

Rule nr. 2: The modal verbs drop their umlauts (ä, ö, and ü) in the past tenses.

Rule nr. 3: Phrases in the perfekt tense require double infinitive structure. Start with auxiliary verb haben conjugated, while the main verb and the modal verb both will come at the end of the sentence in their infinitive forms.
Example: Ich habe Deutsch lernen müssen. ( I have to learn german)

Exception 1: When main verb is missing in our phrase, we will use the past participle form of the modal verbs: gekonnt, gemusst, gesollt, gewollt etc.
Exception 2: Mögen doesn't use double infinitives, instead uses a form of haben with gemocht.

Rule nr. 4: In the past participle auxiliary verb comes first, followed by the main verb while the modal verb comes at the end in its infinitive form.

Rule nr. 5: The future tense and the konjunktiv I of modal verbs are regular tenses while in konjunktiv II the endings of modal verbs are those of the simple past.

Modal verbs

Rules for modal verbs