Time zones: defined by their offset from Coordinated Universal Time (UTC) | Photo: Shutterstock

What time is it? Here's how a common daily question can have multiple answers. Welcome to the complex world of time zones.

We all live in different time zones. As a result, time is always different in various places on the planet.

When you fly between Los Angeles and New York, you must add three hours to your clock upon arriving at your destination.

And while someone is waking and getting ready for another working day under sunny skies, another is heading off to bed under the moonlight.

Ideally, the planet would be divided between 24 identical time zones, each representing one hour of the day.

However, in a world with borders, political, geographical, social interests, and lobbies, the officially established time zones make the planet look like a complicated geometrical drawing of longitudinal lines.

They're technically named meridians, i.e., imaginary lines that run vertically from the North Pole to the South Pole, each 15 degrees apart.

With the rotation of the Earth, from east to west, each meridian represents one given hour. So, we all end up getting 24 standard time zones and 14 additional exceptions.

As a result, local time always depends on what time zone you're in at a given moment.

As stated above, all nations have specific interests, so the time zone map is not as linear as it should be in theory.

Take a look at the official world time zone map. Click on the image below to zoom in.

The World Time Zone Map

The Differences Between GMT, UTC, and IDL

The official time standard regulating the world's time and clocks is called Coordinated Universal Time (UTC).

It replaced the Greenwich Mean Time (GMT) in the late 1960s, even though GMT remains today as a regional time zone at UTC+00:00.

UTC is precisely the same imaginary line defined by GMT at the Prime Meridian, located in the Royal Observatory in Greenwich.

Nevertheless, many people still use GMT as the time standard for all countries worldwide - for example, GMT+12:00 for New Zealand.

But there's also another important formalism - the International Date Line (IDL).

IDL is another imaginary line that passes through the middle of the Pacific Ocean and determines where you cross from one day to the next.

That is why countries located immediately west of the IDL - Tonga, Samoa, and Kiribati - are the first to celebrate the New Year.

There are two ways of establishing time on planet Earth - the atomic clock and solar time.

Atomics clocks are complex timekeeping mechanisms run by national governmental agencies and used on specific occasions, technologies, and systems.

Solar time is the formula used to set civil time via UTC.

Prime Meridian: the imaginary line used to indicate zero degrees longitude can be seen at the Royal Observatory, in Greenwich, England | Photo: Hausken/Creative Commons

Time Offset and Time Zones

A time offset is the amount of time added to or subtracted from UTC.

In other words, the time zone map indicates positive or negative offsets from UTC using the codes UTC- or UTC+ and the corresponding number of hours and minutes.

For instance, at UTC±00, you'll find the United Kingdom; at UTC+14:00, you'll get Kiribati's Line Islands.

Take a look at all time zones around the world.

Here's a simplified, non-detailed list of the 38 UTC time offsets and the corresponding countries:

UTC-12:00 | United States;

UTC-11:00 | New Zealand, United States, American Samoa;

UTC-10:00 | France, New Zealand, United States;

UTC-09:30 | France;

UTC-09:00 | France, United States;

UTC-08:00 | United Kingdom, Canada, Mexico, France, United States;

UTC-07:00 | Canada, Mexico, United States;

UTC-06:00 | Belize, Costa Rica, El Salvador, Guatemala, Honduras, Nicaragua, Chile, Ecuador, Canada, Mexico, United States;

UTC-05:00 | Colombia, Cuba, Haiti, Jamaica, Panama, Brazil, Bahamas, Ecuador, Peru, United Kingdom, Canada, Mexico, United States;

UTC-04:00 | Barbados, Bolivia, Brazil, Chile, Dominica, Dominican Republic, Grenada, Guyana, Paraguay, Saint Kitts and Nevis, Saint Lucia, Saint Vincent and the Grenadines, Venezuela, Denmark, Antigua and Barbuda, Trinidad and Tobago, Netherlands, United Kingdom, Canada, France, United States;

UTC-03:30 | Canada;

UTC-03:00 | Suriname, Uruguay, Argentina, Brazil, Chile, Denmark, Antarctica, United Kingdom, France;

UTC-02:00 | Brazil, United Kingdom;

UTC-01:00 | Portugal, Cape Verde, Denmark;

UTC±00:00 | Burkina Faso, Gambia, Ghana, Guinea, Guinea-Bissau, Iceland, Ivory Coast, Liberia, Mali, Mauritania, São Tomé and Príncipe, Senegal, Sierra Leone, Togo, Denmark, Ireland, Spain, Portugal, United Kingdom, Antarctica;


Current Coordinated Universal Time (UTC)

UTC+01:00 | Albania, Algeria, Andorra, Austria, Belgium, Bosnia and Herzegovina, Croatia, Czech Republic, Denmark, France, Germany, Hungary, Italy, Kosovo, Liechtenstein, Luxembourg, Netherlands, Malta, Monaco, Montenegro, Morocco, North Macedonia, Norway, Poland, San Marino, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Tunisia, United Kingdom, Vatican City, Angola, Benin, Cameroon, Central African Republic, Chad, Equatorial Guinea, Gabon, Namibia, Niger, Nigeria, Republic of the Congo, Democratic Republic of the Congo;

UTC+02:00 | Eswatini (Swaziland), Israel, Jordan, Lesotho, Palestine, Sudan, Botswana, Burundi, Malawi, Mozambique, Rwanda, South Africa, Zambia, Zimbabwe, Bulgaria, Cyprus, Egypt, Estonia, Finland, Greece, Latvia, Lebanon, Libya, Lithuania, Moldova, Romania, Russia, United Kingdom, Ukraine, Syria;

UTC+03:00 | Bahrain, Iraq, Yemen, Kuwait, Qatar, Saudi Arabia, Comoros, Djibouti, Eritrea, Ethiopia, Kenya, Madagascar, Somalia, South Africa, South Sudan, Tanzania, Uganda, Belarus, Turkey, Russia, Antarctica, France;

UTC+03:30 | Iran;

UTC+04:00 | Armenia, Azerbaijan, Georgia, Russia, Oman, United Arab Emirates, Mauritius, Seychelles, France;

UTC+04:30 | Afghanistan;

UTC+05:00 | Maldives, Russia, Tajikistan, Turkmenistan, Australia, Kazakhstan, Pakistan, Uzbekistan, Antarctica, France;

UTC+05:30 | India, Sri Lanka;

UTC+05:45 | Nepal;

UTC+06:00 | Kyrgyzstan, Russia, Bangladesh, Bhutan, China, Antarctica, United Kingdom;

UTC+06:30 | Australia, Myanmar;

UTC+07:00 | Russia, Cambodia, Laos, Mongolia, Vietnam, Thailand, Indonesia, Australia, Antarctica;

UTC+08:00 | Russia, Australia, China, Indonesia, Brunei, Taiwan, Hong Kong (China), Macau (China), Malaysia, Philippines, Singapore;

UTC+08:45 | Australia;

UTC+09:00 | Russia, Indonesia, East Timor, Palau, Japan, South Korea, North Korea;

UTC+09:30 | Australia;

UTC+10:00 | Russia, Australia, Papua New Guinea, Federated States of Micronesia, Antarctica, United States;

UTC+10:30 | Australia;

UTC+11:00 | Russia, Australia, Papua New Guinea, Federated States of Micronesia, Solomon Islands, Vanuatu, Antarctica, France;

UTC+12:00 | Russia, Fiji, Marshall Islands, Nauru, Tuvalu, Kiribati, Antarctica, France, New Zealand, United States;

UTC+12:45 | New Zealand;

UTC+13:00 | Kiribati, Samoa, Tonga, New Zealand;

UTC+14:00 | Kiribati;

And which country has the most time zones? Interestingly, despite being the largest country on the planet, Russia is not the correct answer.

In fact, France is the nation with the most time zones.

Due to all its overseas regions, departments, and administered territories, the French authorities have to deal with 12 different time zones.

On the other hand, Nicosia, in Cyprus, is the only world capital whose citizens follow two time zones.

Always keep in mind that time zones tend to - but not necessarily - follow the boundaries of countries. And there are also dozens of time zone abbreviations, names, and codes for Standard Time and Daylight Saving Time (DST).

For example, Hawaii-Aleutian Standard Time (HST), Pacific Time (PST/PDT), Eastern Standard Time (EST), Central Time (CST/CDT), British Summer Time (BST), or even Mountain Time (MT).

The Daylight Saving Time (DST)

The time when the clock is moved forward is called Daylight Saving Time (DST).

George Hudson suggested the practice in 1895. The idea is to give people more sunlight in the summertime after work.

Germany was the first nation to implement DST in 1916. As of August 2019, 70 countries have adopted this procedure.

The DST clock shift usually occurs in March (clocks advance one hour) and is reverted between October and November.

As a general rule of thumb, the further a country is from the equator, the more likely it uses DST. 

Last but not least, UTC never changes with changes in seasons. In other words, UTC does not reflect or observe daylight saving times.

Time Zone Converters

A time zone converter is a tool that quickly calculates the time difference between two locations on the planet.

It answers, for instance, classic questions like when the time in London is 5 pm, what is the time in Los Angeles?

Instead of doing the math using the corresponding UTC time offsets listed above, these online tools allow you to add two locations and immediately get the local time in both places.

The best time zone converters consider DST and enable you to check past, present, and future dates.

If you wish to check the time and date in major world cities and countries at a given moment, try worldtimebuddy.com, time.is, greenwichmeantime.com, timeanddate.com.

Alternatively, subtract or add the corresponding hours and minutes using the table above featuring your desired UTC time zones.

Words by Luís MP | Founder of SurferToday.com

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