Why it matters
Time zone bugs are some of the hardest to spot: a job scheduled for 01:30 on the night the clocks go back runs twice, one at 01:30 on the night they go forward never runs, and an offset stored instead of a zone breaks every summer.
This explorer uses your browser's built-in time zone database to convert times exactly, list every clock change in a year, and warn when a local time is skipped or repeated. The meeting grid shows the working-hours overlap across up to 10 zones. The Timestamp Converter handles Unix times; this tool is about zones and daylight saving.
How it works
- InputA date, time and zone
- In your browserResolved with the browser's time-zone data
- OutputTimes elsewhere, DST changes and a meeting grid
Where it fits in a designer's workflow
- Plan
- Design
- Build
- Test
- Launch
By the numbers
Show the numbers as a table
| Zone | 15 January | 15 July | Changes in 2026 |
|---|---|---|---|
| Europe/London | UTC | UTC+1 | 2 |
| America/New_York | UTC−5 | UTC−4 | 2 |
| Australia/Sydney | UTC+11 | UTC+10 | 2 |
| Asia/Kolkata | UTC+5:30 | UTC+5:30 | 0 |
| Asia/Tokyo | UTC+9 | UTC+9 | 0 |
| America/Sao_Paulo | UTC−3 | UTC−3 | 0 |
How to use it
- Choose a zone and a local date and time.
- List the zones to compare with.
- Check the clock changes for the year.
- Use the grid to find a meeting time.
FAQ
Why does 01:30 appear twice?
When clocks go back, the hour before the change repeats. Pick which one you mean; schedulers should store UTC or the offset to tell them apart.
What happens to a time that doesn't exist?
When clocks go forward, an hour is skipped. Most libraries move such a time forward by the gap, which is what the tool shows.
Should I store offsets or zones?
Store the instant in UTC, plus the IANA zone name for anything shown or repeated in local time. Offsets change with daylight saving; zone names don't.
Where does the zone data come from?
Your browser's copy of the IANA tz database, so it's as up to date as your browser.
