What this converter does
Convert a date and time from one time zone to another, using the IANA time zone database so daylight saving transitions are handled correctly for the date you enter, not just today.
Why daylight saving trips people up
The offset between two zones changes twice a year and the dates differ by country, so a fixed offset is wrong for part of the year. Some zones have also changed their rules at short notice. Always convert using named zones such as Europe/Berlin and America/New_York rather than fixed offsets like UTC+1.
Frequently asked questions
What is the difference between UTC and GMT?
For practical purposes they are the same offset, zero. GMT is a time zone name with historical baggage; UTC is the modern standard. Use UTC in data and logs, and convert to a local zone only for display.
Why are time zone abbreviations such as IST ambiguous?
Abbreviations are not unique. IST can mean India Standard Time, Irish Standard Time or Israel Standard Time, with different offsets. Use IANA names such as Asia/Kolkata, which are unambiguous.
Does it handle daylight saving automatically?
Yes. Conversions use the full IANA rules for the date you entered, so an August date in New York uses EDT and a January date uses EST, without you doing anything.
Why do meetings sometimes shift by an hour after a rule change?
Because one of the countries changed its daylight saving dates. Recurring meetings stored as a fixed offset drift; meetings stored with a named zone follow the new rules.