Time Zone Converter

This converter uses the IANA time zone database that ships with your browser through the Intl API — the same data used by Linux, macOS, Java and most programming languages. Zones are named by region and city, such as America/New_York or Asia/Kolkata, rather than by abbreviation, because abbreviations are ambiguous: CST is Central Standard Time in the US, China Standard Time and Cuba Standard Time. Each zone carries its full history of offset and daylight-saving changes, so converting a date in the past or future gives the offset that applied on that day.

Daylight saving time creates two edge cases. When clocks spring forward, a local time such as 02:30 does not exist; the tool moves it forward by the size of the gap and says so. When clocks fall back, a time like 01:30 happens twice; the tool uses the first occurrence. US and European transitions happen on different weekends, so for a few weeks each spring and autumn the gap between New York and London is four hours instead of five.

The city table shows the same instant in 20 cities sorted by UTC offset, marks 09:00–17:59 on weekdays as working hours, and flags cities that are already on the next or previous calendar day — handy for scheduling a meeting across teams. Non-hour offsets such as India (UTC+05:30) and Nepal (UTC+05:45) are handled. The ISO 8601 output includes the offset, ready to paste into an API or a calendar invite.