When do you use am, im, or um for time in German?

The three preposition contractions cover the vast majority of time expressions. am (= an + dem) is used for days of the week and parts of the day: am Montag, am Morgen, am Abend. im (= in + dem) is used for months, seasons, and centuries: im Januar, im Sommer, im 21. Jahrhundert. um is used for clock time: um 8 Uhr, um halb neun. Memorising these three contractions covers the majority of time expressions a learner will encounter.

How do you say "since" in German?

Use seit + Dativ + present tense. The tense choice is the top mistake: English speakers use perfect tense ("I have been learning for 3 years"), but German uses the present: Ich lerne seit drei Jahren Deutsch. The action started in the past and is still ongoing — German signals this with present tense + seit, not a perfect construction. seit declines its object in the Dativ: seit einem Jahr, seit drei Monaten, seit dem Montag.

What is the difference between seit, vor, and für?

All three can translate as English "for", which is why English speakers confuse them. seit = "since / for up to now" (ongoing; Dativ + present tense): Ich wohne seit zwei Jahren in Berlin. vor = "ago" (completed; Dativ + past tense): Ich bin vor zwei Jahren nach Berlin gezogen. für = "for a bounded, future-oriented duration" (Akkusativ): Ich fahre für eine Woche nach Wien. The temporal reference point determines which to use: still happening now → seit; completed in the past → vor; planned or bounded ahead → für.

How do you say a year in German?

A standalone year is stated as a bare cardinal number with no preposition or article: 2026, 1989. If the word Jahr is used, then im Jahr 1989 is correct. The most common English-speaker error is *im 2026 by analogy with im Januar — this is ungrammatical. When stating the year a sentence belongs to, either use the bare number (Er wurde 1990 geboren) or the full phrase im Jahr 1990.

How do you tell the time in German?

Clock times use um X Uhr for exact hours: um acht Uhr, um 20 Uhr. For half-hours, German counts forward to the next hour: halb neun = half-past eight (8:30), not half-past nine — this is the most common English-speaker confusion. Quarter-hours: Viertel nach acht = quarter past eight (8:15); Viertel vor neun = quarter to nine (8:45). Note: Germans say vor (not zu) for "quarter to" — *Viertel zu neun is non-standard. In spoken German the 12-hour clock is common; in writing the 24-hour clock dominates.

What is the difference between montags and am Montag?

am Montag (capitalized, with article) refers to a specific Monday — this Monday, last Monday, or a contextually anchored Monday: Ich komme am Montag. montags (lowercase, no article, -s suffix) means "on Mondays" in general — every Monday, habitually: Ich gehe montags ins Fitnessstudio. The lowercase -s ending on a day name signals the recurring, habitual reading. This distinction applies to all days: dienstags, mittwochs, donnerstags, freitags, samstags, sonntags.

Where do time expressions go in a German sentence?

Time adverbials can appear in Vorfeld (position 1, before the verb, for emphasis) or in the Mittelfeld (the middle field, after the conjugated verb). Within the Mittelfeld the TeKaMoLo rule orders adverbials: Temporal before Kausal before Modal before Lokal. Ich gehe morgen um 10 Uhr langsam nach Hause — morgen um 10 Uhr (Te) comes before langsam (Mo) which comes before nach Hause (Lo). Time adverbials always come first in the middle field.

Do German speakers use the 12-hour or 24-hour clock?

Both, depending on register. The 24-hour clock is standard in all written and official contexts (timetables, TV schedules, official correspondence): Der Zug fährt um 14:32 ab. In casual spoken conversation Germans typically use the 12-hour clock with context: Wir treffen uns um drei (= 15:00 from context). The digital shorthand uses a colon: 14:32. Spoken times rarely use the word Uhr for quarter-hour forms: you say halb neun and Viertel vor zehn, not halb neun Uhr.

am, im, um — three prepositions cover 90% of when.

German time expressions look like a sprawling vocabulary topic but collapse into two structural patterns: (a) three preposition contractions — am for days and parts-of-day, im for months and seasons, um for clock time — cover most cases; (b) duration splits three ways — seit for ongoing, vor for completed past, für for bounded future. Add TeKaMoLo for word order and you have the whole system.

TL;DR

am: days (am Montag) + parts of day (am Abend). Exception: in der Nacht. im: months (im Januar) + seasons (im Sommer). um: clock time (um 8 Uhr, um halb neun). Duration: seit + present tense (ongoing); vor + past (ago); für + Akkusativ (bounded). Word order: time comes first in the Mittelfeld — TeKaMoLo.

Two rules compress the whole topic

Most resources teach time expressions as twenty-plus separate vocabulary items. There is a faster path. Nearly every German time expression is generated by one of two structural rules:

The am / im / um split — three contracted prepositions decide "when" for days, months, seasons, parts of day, and clock time. Get those three right and ~80% of time expressions fall into place.
The seit / vor / für split — three duration prepositions cover "for how long" and "how long ago". English uses one word ("for") for all three; German keeps them strictly separate by temporal reference point.

A third pattern, TeKaMoLo, governs where any time expression sits in the sentence when multiple adverbials cluster together. The sections below build each rule from scratch.

The am / im / um decision rule

Three contracted prepositions handle the majority of "when" statements. Pick the right one by asking what type of time unit you are naming.

am = an + dem (Dativ)

Days of the week + parts of the day

Days: am Montag, am Dienstag, am Wochenende
Parts of day: am Morgen, am Mittag, am Nachmittag, am Abend
Exception: in der Nacht (not *am Nacht)

Der Kurs beginnt am Montag.

Ich esse am Abend meistens zu Hause.

im = in + dem (Dativ)

Months, seasons, centuries

Months: im Januar, im Februar … im Dezember
Seasons: im Frühling, im Sommer, im Herbst, im Winter
Centuries: im 21. Jahrhundert — decades use in den 1990er-Jahren

Sie fahren im August in den Urlaub.

Das Gebäude wurde im 19. Jahrhundert gebaut.

um clock time only

Exact and approximate clock time

Exact hours: um 8 Uhr, um 20 Uhr
Half-hours (counts to next hour!): um halb neun = 8:30
Quarter-hours: um Viertel nach acht (8:15), um Viertel vor neun (8:45)

Der Zug fährt um 14:32 ab.

Wir treffen uns um halb sieben.

Not covered by am / im / um: bare years (2026 — no preposition); in der Nacht (exception noted above); in einer Woche (in a week's time — in + Dativ); vor dem Mittagessen (before lunch — vor + Dativ).

seit / vor / für — the duration split

English uses one word ("for") to cover all three German duration prepositions. The distinction is the temporal reference point: is the duration still going? completed? or planned ahead?

seit / vor / für — three ways to say duration

TABLE

Präposition	Bedeutung	Kasus	Beispiel
seit	since / for (up to now — ongoing)	Dativ	Ich lerne seit drei Jahren Deutsch.
vor	ago (completed in the past)	Dativ	Ich bin vor drei Jahren nach Berlin gezogen.
für	for (bounded, future-oriented)	Akkusativ	Ich fahre für eine Woche nach Wien.

seit + present tense is the single most common tense mistake made by English speakers.

The seit rule that English speakers always get wrong

✗ wrong

*Ich habe seit drei Jahren Deutsch gelernt.

Perfect tense — incorrect with seit

✓ correct

Ich lerne seit drei Jahren Deutsch.

Present tense — correct

German uses present tense with seit because the action is still ongoing at the moment of speaking. English uses a perfect construction ("I have been learning for three years"), which misleads German learners into reaching for the Perfekt. With seit, present tense is always the right choice when the situation is still true now.

Telling the time: halb and Viertel vor/nach

The German clock system has one critical difference from English: halb counts to the next hour, not from the current hour.