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.

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.