Use a city and a date
A time zone is more than a fixed offset. Cities can change their UTC offsets during the year. London uses UTC+0 in winter and UTC+1 in summer, while New York uses UTC−5 and UTC−4. Their clock changes do not always happen on the same day.
What does UTC mean?
Coordinated Universal Time is the reference used to compare local times. UTC+5:30 means five hours and thirty minutes ahead of UTC. Some offsets include 30 or 45 minutes, so subtracting whole hours is not always enough.
When a local time happens twice
When clocks move back, an hour repeats. In New York, for example, 1:30 am on the autumn transition date can refer to two different moments. TimeThere offers both occurrences with their UTC offsets. Confirm which one your event organizer means.
When a local time does not exist
When clocks move forward, they skip part of the local day. A time in that gap cannot be converted to a real instant. TimeThere asks you to pick another time rather than silently changing your input.
Time zone abbreviations can be ambiguous
CST may mean Central Standard Time or China Standard Time. IST may refer to different regions. Choose a city such as Chicago, Beijing or Mumbai to make your intention clear.
Where the rules come from
TimeThere uses your browser’s internationalization support and its time zone data. Governments can change time rules, so keep your device updated and confirm critical schedules with the organizer. Learn more from the IANA Time Zone Database and daylight saving reference.