DST Transition Finder

Scan the browser’s IANA time-zone data for offset transitions and show when clocks move forward or backward.

IANA time zone

Year

—Offset changes

—January offset

—July offset

Transition instant	Before	After	Clock change

This scans the browser’s bundled IANA time-zone rules. Future laws can change after your browser was released.

Core timing workflows

Start with a direct timer, stopwatch, alarm or focus workflow. Calendar, date arithmetic, clocks and scheduling specialists remain available from the full Date & Time hub.

All 76 date & time tools

Online TimerCountdown, sound, repeat & fullscreen StopwatchLaps, precision & fullscreen Countdown TimerFocused countdown workflow Alarm ClockAlarm at a local clock time PomodoroFocus and break cycles Interval TimerWork/rest rounds Presentation TimerTalk timing with warnings Classroom TimerProjector-friendly countdown

Find clock changes in a year

Choose an IANA time zone and year. The tool scans the browser time-zone data for UTC-offset changes, then narrows each transition to roughly the minute and shows the before/after offsets.

Future-rule caution

Time-zone laws can change. Future results are only as current as the IANA data shipped with the user’s browser.

Time-zone data boundary

The tool scans the browser’s bundled IANA time-zone rules for UTC-offset changes. A zone can have zero, one, two, or unusual transitions, and future legislation can outdate browser data.