Daylight saving dates checker
Type an IANA time zone such as Europe/Berlin or America/Chicago and a year. The checker finds every clock change in that year by reading the zone's UTC offset from your browser, and shows the date, local time, and size of each change.
Runs in your browser: nothing you enter is sent anywhere.
How to use it
- Type the IANA name of a time zone.
- Type a year from 1970 to 2100.
- Read the list of clock changes with their local date and time.
How it works
The checker samples the zone’s UTC offset every 12 hours, using your browser’s built-in time zone data. When two neighbouring samples differ, it bisects the interval down to one minute to find the first moment with the new offset. It then converts that moment to the local clock before and after the change. Changes of the standard time itself are listed the same way.
Worked example
For America/New_York in 2026 the checker lists two changes:
- Sunday, 8 March 2026: 2:00 AM becomes 3:00 AM, clocks forward 60 minutes, UTC−5 to UTC−4 (at 07:00 UTC).
- Sunday, 1 November 2026: 2:00 AM becomes 1:00 AM, clocks back 60 minutes, UTC−4 to UTC−5 (at 06:00 UTC).
Europe/London in 2026 changes on 29 March and 25 October, and Australia/Lord_Howe changes by 30 minutes instead of 60.
Tips
- To convert a time across zones, use the time zone converter.
- Set a calendar event in the zone name, not in a fixed offset, so it follows the changes.
Frequently asked questions
How does the checker find the dates?
It reads the UTC offset of the zone every 12 hours across the year. Where the offset changes, it narrows the moment down to the minute. No dates are stored in the tool.
Why can the result differ from another source?
Time zone rules change by law, and browsers update their data at different times. For years far ahead the dates are only a projection of the current rules.
What does no clock changes mean?
The zone has the same UTC offset all year, as with Asia/Tokyo. Some places keep daylight saving time all year and some do not change at all.
Why do two changes in the southern hemisphere come in a different order?
Where summer is in December, the clocks go back in the autumn, around April, and forward in the spring, around October. The list is sorted by date.