The World Clock

What Is a Time Zone? The term time zone can be used to describe several different things, but mostly it refers to the local time of a region or a country. Our Time Zone Map is always current. At timeanddate.com we define a time zone as a region where the same standard time is used. Time Difference from UTC The local time within a time zone is defined by its offset (difference) from Coordinated Universal Time (UTC), the world's time standard. UTC time changes 1 hour forward and backward corresponding to a 1-hour difference in mean solar time for every 15 degrees east or west of the prime meridian (0° longitude) in Greenwich, London, United Kingdom. The offset is expressed as either UTC- or UTC+ and the number of hours and minutes. Interactive Time Zone Map More Than 24 Time Zones If each time zone were 1 hour apart, there would be 24 in the world. However, the actual borders on the time zone map have been drawn to match up with both internal and international borders, and rarely match up exactly with the 15-degree longitudes. Also, the International Date Line (IDL), creates 3 time zones and several time zones are only 30 and 45 minutes apart. This makes the total number of time zones worldwide much higher. Daylight Saving Time Zones Regions that use Daylight Saving Time (DST) change the time zone name and time during the DST period. The words “daylight” or “summer” are then usually included in the time zone name. The areas that don't use DST remain on standard time zone all year. For example, California uses Pacific Daylight Time (PDT) during the DST period, but Pacific Standard Time (PST) during the rest of the year. Not the Same as Local Time The term time zone is often used instead of local time. For instance, during DST, it is common to say “California and Arizona are now in the same time zone.” However, the correct thing to say would be: “California and Arizona now have the same local time.” The reason is that California's local time during DST is UTC-7, but the standard time in California is minus one more hour: UTC-8. However, Arizona's local time is always UTC-7, because there's no DST in Arizona, and they remain on standard time all year.