How Many Time Zones Are There?

A time zone is an area or stretch of land that observes a uniform standard time for legal, commercial, and social purposes. It is used to mark the hours of the day in different locations. Time zones are needed because people in different places experience the hour at different times of the day. If each location has a different time zone, how many time zones are there in the world?

If there’s an hour difference between each time zone, therefore, there’s a total of 24 time zones. The Earth completes one full spin every day which is equal to 360 degrees. If you divide 360 degrees by 24 hours, it will result in an hourly rotation of 15 degrees, which is the width of each time zone. Location and time are both relative quantities. Meaning, they must be measured in reference to a known point. In time zones, the meridian of reference is called the Prime Meridian. It begins where it ends, which is in the Royal Observatory in Greenwich, England, also known as Longitude 0º. However, several time zones only have 30 and 45 minutes’ offsets which makes the total number of time zones higher than 24.

Time Zone Borders Vary

Based on the scientists who introduced time zones, each 1-hour time zone is 15 degrees wide, which indicates an hour difference in mean solar time. However, the borders that can be seen on an actual time zone map adheres to both internal and external borders, and rarely match up exactly with the 15-degree time zone borders. An example is India and China which observes only one national time even though their cities are in different time zones.  

Daylight Saving Time Zones

During Daylight Saving Time (DST), the time zone name and time are changed, and the words “summer” and “daylight” are usually included in the name. Also, the time is set forward for an hour. An example is California which usually uses Pacific Standard Time (PST) with an offset of UTC -8 during the whole year, but when DST period comes, it changes to Pacific Daylight Time (PDT) with a UTC offset of UTC -7.

UTC Offset

Each of the regions on Earth has their distance measured east or west of the prime meridian (0º longitude) which theoretically, is placed in Greenwich, London in the United Kingdom. It also serves as a reference mark for the Coordinated Universal Time (UTC) having one hour for every 15 degrees’ longitude. To determine the precise time zones in hours, a particular longitude in degrees has to be divided by 15.

The Difference with Local Time

Some are often confused with time zones and local time but they are different. For example, during Daylight Saving period, some would say California and Arizona are in the same time zone, but the correct way to say it is, California and Arizona now have the same local time. Since California’s local time during DST is UTC-7, but its standard time is UTC-8. On the other hand, Arizona’s local time is always UTC-7, because it does not observe DST. Therefore, it remains on standard time the whole year.

Countries with the Most Time Zones

  • France: France observes twelve time zones because it has many overseas territories. Metropolitan France’s official time is set as GMT+1. Its international territories, on the other hand, fall between UTC-10:00 in most regions of French Polynesia, to UTC+12:00 in the territories of Wallis and Futuna.
  • The US Law: The US law observes nine time zones including its territories and an addition of two unofficial time zones. Also, most parts of the US adhere to Daylight Saving Time during the months of summer, spring, and fall. US time zones include Hawaii, Pacific, Mountain, Eastern, Central, Atlantic, Samoa, and Alaskan.
  • Russia: Russia identifies eleven time zones which include, Omsk, Moscow, Yakutsk, Magadan, Samara, Vladivostok, Yekaterinburg, and Kamchatka.

Uniform Irregularity

The universalized time standard would be more useful if it’s really universal, however, there are some irregularities, inconsistencies, and exceptions with the GMT/UTC system that’s why not all locations use the time zone system. Though some use them, but not during the whole year. Also, in reality, the perimeters of the time zones zigzag east and west which resembles a crack on the fault line rather than the simple and firm separations imagined by scientists. The zoning jigsaw is composed of several localities which claim distinct fractional zones, while some split themselves into multiples. An example is Burma, which is half an hour ahead of Bangladesh to its East, but an hour ahead of India to its West. This is because the Indian Standard Time splits its hour between Pakistan and Bangladesh.

Until now, time zones were still confusing to most people because they can be politically adjusted for different things, like saving energy for instance. Therefore, time itself also remains a mystery.