Weeks, hours, clock changes
Three conversions the German working world takes for granted: the ISO week everyone quotes as “KW”, decimal hours for timesheets, and the two Sundays the clocks move.
The week
ISO 8601, the same as DIN 1355: the week starts on Monday, and week 1 is the one containing the first Thursday. That is where naive implementations go wrong - 31 December 2024 belongs to week 1 of 2025.
KW 40ISO year 2026
28 Sept 2026 → 04 Oct 2026
28 Sept 2026 → 04 Oct 2026
This ISO year has 53 weeks
The working day
German time-recording wants decimal hours: 2:15 goes in as 2.25. Break included, because a timesheet without one is no use.
Written as you like: 8:30, 8h30 or 8.5. A finish before the start is counted over midnight.
The clock change
European rule: the last Sunday in March and the last Sunday in October, at the same moment across the whole Union.
- Sunday, 29 March 202602:00 → 03:00 Summer time begins - one hour lost was 189 days
- Sunday, 25 October 202603:00 → 02:00 Winter time begins - one hour gained in 21 days