Daylight Saving Time Calculator
Find daylight-saving time offset changes in a selected year and time zone.
Calculator
Results
How it works
Find daylight-saving time offset changes in a selected year and time zone.
Example
| Example | Result |
|---|---|
| Europe/London has two offset transitions in 2026. | See calculator |
Important notes
- Calendar calculations use Gregorian calendar rules.
- Business-day calculations exclude Saturday and Sunday unless stated otherwise.
- Time-zone calculations depend on the browser's IANA time-zone data.
- For planning purposes, verify dates and times when a contractual or legal deadline is involved.
Frequently Asked Questions
Does this use official DST rules?
It uses the browser’s IANA time-zone database, which reflects the time-zone rules available to that browser.
Can a zone have zero transitions?
Yes. Zones without seasonal offset changes return no transitions.
How to use this calculator
What to enter
Enter or select the following as requested: Year; Time zone. Follow the units, valid ranges, examples, and options displayed beside each field.
What the result means
The date or duration result is calculated from the entered dates, times, calendar rules, and exclusions. Check inclusive versus exclusive counting, time zone, daylight-saving changes, and whether weekends or holidays are excluded.
When to use it
Use this to plan a date, measure elapsed time, or estimate a deadline. Verify the relevant calendar, location, and legal or workplace rules when they affect the answer.