Time Zone Converter

It uses the browser’s built-in time zone database (the same IANA data your phone uses), so every conversion applies the exact daylight-saving switch dates for the date you enter — US zones change on the second Sunday in March and first Sunday in November, Europe on the last Sundays of March and October, Australia in October and April, and India, Japan, China and Arizona never change.

EST is Eastern Standard Time (UTC−5), used in winter; EDT is Eastern Daylight Time (UTC−4), used from March to November. People say “EST” all year, and this converter treats EST as “Eastern Time” and picks the right one for the date. The same goes for CST/CDT, MST/MDT and PST/PDT.

UTC (Coordinated Universal Time) is the atomic-clock standard all zones are defined against; it never changes with the seasons. GMT is the historical name for the same zero offset, but the UK actually moves to BST (UTC+1) in summer. Aviation, servers and log files use UTC (also written Z or “Zulu”).

Hawaii and most of Arizona (except the Navajo Nation) stay on standard time all year, as do Puerto Rico, Guam, American Samoa and the US Virgin Islands. That is why Arizona matches Pacific Time in summer and Mountain Time in winter.

Six in the states — Eastern, Central, Mountain, Pacific, Alaska and Hawaii-Aleutian — plus Atlantic (Puerto Rico), Samoa and Chamorro (Guam) in the territories, nine in all. Contiguous-US zones are one hour apart, so Eastern is three hours ahead of Pacific.