Time Zone Converter

Time zones are regions of the earth that observe the same standard time. The world is divided into 24 primary time zones, each approximately 15 degrees of longitude wide, corresponding to one hour of time difference. However, the actual boundaries follow political and geographic lines, resulting in some irregularities and half-hour or quarter-hour offsets.

The modern time zone system was established in the late 19th century to standardize timekeeping for railroad schedules. Before that, each city set its own local time based on the position of the sun. The International Meridian Conference of 1884 established the Greenwich meridian as the prime meridian and the basis for the Universal Time system.

Daylight Saving Time (DST) adds complexity to time zone conversions. Most of North America and Europe adjust clocks forward by one hour in spring and back in fall. However, the dates of these changes differ between regions. Some places, like Arizona, Hawaii, and most of Asia and Africa, do not observe DST at all. This means the time difference between two cities can change throughout the year.

This converter uses the IANA time zone database (also known as the Olson database) through the browser's Intl API to handle DST transitions and historical time zone changes accurately. Simply select the source and destination time zones, enter the time you want to convert, and get instant results.