Time Zone Converter — Convert Time Between Cities

A UTC offset is not a timezone

If someone tells you a meeting is at "UTC+1", you do not know what time it is in London on any given day. London is Europe/London in IANA notation, and in winter it sits at UTC+0, but in summer (the last Sunday of March through the last Sunday of October) it jumps to UTC+1 for daylight saving time. A raw offset like "UTC+1" could be London, Paris, Berlin, or any one of dozens of other zones — and in several of them that offset is wrong for half the year.

The non-existent hour and the doubled hour

On the day clocks spring forward, 2:00 AM does not exist in your timezone. On the day they fall back, 2:00 AM happens twice. A naive tool that just adds or subtracts an offset will not see these holes and doubles — it will confidently give you a wrong time, or an ambiguous one. This tool uses the browser's built-in timezone engine (Intl.DateTimeFormat) paired with IANA zone names to ask the operating system what the offset was at that exact wall-clock moment. It resolves both the spring-forward gap and the fall-back ambiguity correctly.

Every city in the tool resolves its own DST rules

Pick a date and time in one city, see it in another — or toggle Live to lock both to the current moment and watch the clocks tick together. The tool auto-detects your browser's local timezone on load and covers cities across every major zone. Copy the result for pasting into emails or documents.

Accuracy depends on your system's timezone database

IANA timezone rules are maintained centrally and updated whenever a country changes its DST rules. This tool uses the rules embedded in your operating system or browser, which may be weeks or months behind the official database if your OS is not updated. For historical dates well before 1970, the data is not reliable.

For related conversions, see the Unix Timestamp Converter and the Date Difference Calculator.