Zeitrechner
Startzeit plus/minus Dauer — mit Mitternachtswechsel und 12/24-Stunden-Anzeige.
Berechnen
Berechnen
Ergebnis
Die Formel
Convert the start clock time to minutes since midnight, add or subtract (hours×60 + minutes), then normalize with modulo 1440. Positive day shifts mean the result falls on a later calendar day; negative shifts mean an earlier day.
Rechenbeispiel
- Start 09:30 → 570 minutes
- Add 2h 45m = 165 minutes → 735
- 735 → 12:15 (same day)
Ergebnis: 09:30 + 2h 45m = 12:15
How time add/subtract works
Clock arithmetic is modular: after 23:59 comes 00:00. This tool tracks how many midnights you cross.
Input formats
Use HH:MM in 24-hour form (09:30, 21:15) or append am/pm (9:30 am). Duration fields are decimal-friendly (e.g. 1.5 hours = 90 minutes when minutes are 0 — prefer whole hours + minutes for clarity).
Overnight wrap
22:00 + 3h = 01:00 next day. 01:00 − 2h = 23:00 previous day. The day-shift badge shows when the result leaves the starting civil day.
What we do not model
No time zones, DST transitions, or seconds. For calendar spans in days, use date difference or days-until.
Interessante Fakten
1440 minutes/day
A civil day has 24 × 60 = 1440 minutes — the modulus used for wrap-around.
12-hour ambiguity
“12:00 am/pm” conventions vary in speech; we treat 12:00 AM as midnight and 12:00 PM as noon.
Duration ≠ clock
Adding 25 hours is valid: the clock shows +1 day and the leftover hours.
Sibling tools
Date difference counts days between dates; this tool moves a time-of-day by a duration.
Sleep planner
For bedtime + N sleep cycles, use the sleep calculator instead.
Häufig gestellte Fragen
09:30, 2 Stunden, 45 Minuten, Addieren → 12:15.
Ja, mit +1 oder −1 Tag.
am/pm eingeben oder Anzeige 12h wählen.
Operation Subtrahieren wählen.