what is it?
Temporal prepositions are words that place an event in time — pinning it to a clock time, a day, a month, a season, or a duration. German uses a fixed set of prepositions for this purpose, each paired with a specific type of time expression and a specific grammatical case. The choice of preposition is not optional: using the wrong one (or omitting one that is required) produces an ungrammatical sentence. A small but important group of time expressions takes no preposition at all and instead uses a bare accusative noun phrase.
when to use it
am — use with days of the week and parts of the day (morning, evening, etc.). am Montag, am Abend. Exception: in der Nacht (night uses in, not am).
um — use with clock times. um neun Uhr, um Mitternacht. Never use um with days or dates.
im — use with months and seasons. im Juli, im Sommer.
von … bis — use for a span between two points in time. von Montag bis Freitag, von neun bis fünf Uhr.
ab — use for a starting point from which something continues. ab Montag, ab neun Uhr.
vor / nach — use with dative to mean «before» or «after» a time reference. vor dem Kurs, nach dem Abendessen.
in + dative — use for a time interval from now until an event. in zehn Minuten, in einer Stunde.
für + accusative — use for a planned or intended duration. für zwei Tage, für eine Woche.
bare accusative (no preposition) — use with expressions like jeden Tag, den ganzen Abend, nächste Woche, letzten Monat. No preposition is added.
formation
The most important forms to memorise are the contractions. an + dem → am and in + dem → im. These contractions are obligatory — the uncontracted forms are not used in standard German for time expressions. The table below shows each preposition, the case it governs, and the type of time expression it combines with.
| preposition | case | combines with | example |
|---|---|---|---|
| am (an + dem) | dative | days, parts of day | am Montag, am Abend |
| um | accusative | clock times | um neun Uhr |
| im (in + dem) | dative | months, seasons | im Juli, im Sommer |
| von … bis | dative | time spans | von neun bis fünf Uhr |
| ab | dative | starting point | ab Montag |
| vor | dative | before a reference | vor dem Kurs |
| nach | dative | after a reference | nach dem Kurs |
| in | dative | interval until event | in zehn Minuten |
| für | accusative | planned duration | für zwei Tage |
| — (none) | accusative | habitual / whole-span | jeden Tag, nächste Woche |
«Night» is the one common part of the day that does not use am: say in der Nacht, not *am Nacht.
examples in context
common pitfalls
Uncontracted an/in instead of am/im. The contractions are obligatory. *an Montag and *in Juli are ungrammatical. Always write am Montag and im Juli.
Calquing English «at night». English «at night» tempts learners to say *an der Nacht. German uses in der Nacht. Night is the exception to the am-pattern for parts of the day.
Using um with days or dates. um is reserved for clock times only. *um Montag is wrong; the correct form is am Montag.
Adding für to bare accusative duration phrases. Expressions like den ganzen Tag or jeden Tag take no preposition. *für den ganzen Tag bleiben is incorrect; say den ganzen Tag bleiben. Reserve für for planned durations with an indefinite or numeral noun phrase, e.g. für zwei Tage.