A time zone is a region of the world that observes a uniform standard time for legal, commercial, and social purposes, typically defined by its offset from Coordinated Universal Time (UTC).

How many time zones are there in the world?

There are 24 primary time zones based on longitudinal divisions, but considering half-hour and quarter-hour offsets, there are over 38 different time zone offsets used worldwide.

Why do we have time zones?

Time zones were introduced to standardize time across regions and facilitate transportation, communication, and commerce across different geographic locations.

What is UTC and how is it used?

UTC (Coordinated Universal Time) is the primary time standard by which the world regulates clocks and time. All time zones are defined by their offset from UTC (e.g., UTC+5, UTC-8).

How does Daylight Saving Time affect time zones?

Daylight Saving Time shifts the clock forward by one hour during warmer months in some regions, temporarily changing their UTC offset to maximize daylight hours.

Time Zone Abbreviations

Global Time Zone Reference

Complete reference guide to worldwide Time Zone Abbreviations, IANA Identifiers, and UTC Offsets
Use filtering and sorting to find exactly what you need, or use our helpful preset Filters!
Click on an Abbreviation to dive even deeper!
Click on an Offset to change the time to compare with!
Switch between the Complete list and Advanced table for filters, sortable columns, and saved column controls.
Representative IANA time zone (one per row): many abbreviations cover multiple countries, so exact clock-change dates and times vary by location. The table uses one IANA time zone for its transition details; for a full per-zone schedule, use Upcoming DST.