Convert time between India and world time zones with real daylight-saving rules, including non-existent spring-forward times and duplicated fall-back times.
Why not just add or subtract a fixed offset?
Because many zones do not keep one offset all year. New York, London, Sydney, and many others change offset during daylight-saving transitions. A fixed number is wrong exactly on the dates people most need a reliable converter.
What does it mean when a time does not exist?
It means the source zone skipped over that wall time during the spring-forward DST change. The local clock jumped, so there is no real instant to convert. A correct converter must refuse to invent one.
What does it mean when a time happens twice?
It means the source zone repeated that wall time during the fall-back DST change. There are two valid instants one hour apart, and they can convert to two different target times. Both have to be shown.
Why is India the easy side of this conversion?
Because Asia/Kolkata has no daylight saving. The tricky part is almost always the other zone. That is why the page is designed around DST gaps and overlaps rather than around India itself.
Why do you ask for IANA zone names instead of city abbreviations?
Because abbreviations are ambiguous and often change with DST. IST can mean India or Ireland depending on context. IANA names such as Asia/Kolkata and America/New_York are the stable identifiers the platform actually uses.