um + Time

When using um, the meaning depends on whether you are talking about a clock, a calendar, or a difference/change.

1. Clock Time ('At'):
For clock times, um means at. Um acht Uhr means at 8:00. To emphasize 'exactly on the dot', add Punkt or genau (e.g., um Punkt acht Uhr or genau um acht Uhr). Note that with Punkt you may either keep or drop the um—um Punkt acht Uhr and Punkt acht Uhr are both standard. You also use um with fractions of an hour, like um halb sieben (at half past six). To say 'around 8:00', use gegen (e.g., gegen acht Uhr) or add herum (e.g., um acht Uhr herum).

2. Years, Holidays, and Eras ('Around'):
When um is used with years, holidays, or seasons, it means around or circa. Native speakers frequently add herum at the end of the phrase to clarify the estimation. Years and holidays stand without an article, but seasons and calendar dates keep their definite article, and um puts it in the accusative (e.g., um den Sommer herum, um den 15. Mai herum).

• um 1900 herum (around 1900)
• um Ostern herum (around Easter)
• um den Sommer herum (around summertime)
• 1995 or im Jahr 1995 (in 1995 - specific)

3. Differences and Changes ('By'):
You can use um to express a time difference or shift, which translates to by in English. For example: Wir verschieben das Meeting um eine Stunde (We are postponing the meeting by one hour). It is also very common when talking about being early or late with verbs of change: Er hat sich um zehn Minuten verspätet (He was delayed by ten minutes). Note that with zu spät sein or zu spät kommen, the um is usually omitted (e.g., Er ist zehn Minuten zu spät). This same rule applies to numbers, prices, and percentages: Die Preise steigen um zehn Prozent (Prices are rising by ten percent).

4. Usage with 'Uhr':
You can use um with the word Uhr (o'clock) or just the number:

• um neun Uhr (standard)
• um neun (casual)

5. Asking the Time:
To ask 'At what time...?', use the essential phrase Um wie viel Uhr...? (e.g., Um wie viel Uhr beginnt der Film?). You can also simply ask Wann...? (When...?).

6. Special Cases (Mittag/Mitternacht):
For 'at midnight', use um Mitternacht. For exactly noon (12:00), use um 12 Uhr or um zwölf. The phrase um Mittag actually means 'around noon' or 'at midday'. Because Mittag is a part of the day, standard grammar uses am Mittag for the midday period. To say 'around noon' or 'around lunchtime', you can also use the highly frequent phrase um die Mittagszeit or gegen Mittag. Note that to say 'for lunch', Germans use the highly frequent phrase zu Mittag (e.g., Wir essen zu Mittag).

7. The Accusative Case:
The preposition um always triggers the accusative case. While invisible with numbers, it appears clearly with articles and adjectives: um den 15. Mai herum (around May 15th), um diese Zeit (around this time), and Wir verschieben es um einen Tag (We are postponing it by one day).

8. The Big Three: um vs. am vs. im:
English speakers often confuse these prepositions. Remember this simple rule: use um for clock times (um acht Uhr), am for days and parts of the day (am Montag, am Morgen), and im for months, seasons, and years (im Mai, im Sommer, im Jahr 2020).

9. Repetitive Sequences ('After'):
You can use um with time nouns to mean 'after' in repetitive sequences. For example, Tag um Tag means 'day after day', and Jahr um Jahr means 'year after year'.

10. False Friends for 'At':
English speakers often try to translate 'at' directly to um in contexts where it doesn't belong. For example, 'at 18 years old' is mit 18 (never um 18), and 'at night' is in der Nacht or nachts (never um Nacht).