Number of time zones in the world - Flytrippers - EU-Vietnam Business Network (EVBN)

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The number of time zones in the world is a bit surprising. Since there are 24 hours in a day, there should be just 24 time zones in theory (1 for each hour). But there are more than 24 time zones; a lot more. There are actually a whopping 38 time zones in the world, for 2 main reasons.

It’s the last day of 2022 for us here in Canada, but it’s already 2023 in some places, as you surely know. All because of time zones, of course.

So let’s look at the number of time zones in the world.

Basics of time zones in the world

The Earth is a sphere, so that’s 360 degrees in longitude. It rotates on its axis, so that gives us night and day periods. That rotation process takes 24 hours, so that’s the length of a day.

So, in theory, that would make a nice even 24 time zones if each time zone were just 1 hour apart and were set according to distances only. Each time zone would measure 15 degrees (360 degrees divided by 24 hours) and would represent a 1-hour difference in solar time.

But it’s not that simple. We have those 24 time zones, of course. But there are more.

Map of time zones in the world

There are in fact 38 time zones in the world, over 50% more than it could be if things were kept simple.

This color-coded map shows them well, but we’ll get back to it in a second.

First, time zones don’t just follow the longitudinal lines: they were adapted to follow regional and national borders for convenience.

Imagine if major cities had a time zone line right in the middle! That would make no sense. Other countries are huge and should have multiple time zones, but their government wants everyone to have the same time (like in China, for example).

Those modifications have created quite a few quirks on the time zone map, which I’ll cover in a separate post soon (like the neighboring islands with a 26-hour time difference and how to jump forward 3.5 hours in 1 step, in theory).

But that just explains the weird time zone borders, not the reason there are 38 time zones instead of 24.

So let’s look at those slight complications.

What explains the number of time zones in the world

There are 3 “types” of time zones, if we can call them that:

24 basic time zones (1 for each hour)
11 special offset time zones (not in even 1-hour increments)
4 bonus time zones (around the International Date Line)

Yes, 38 is the number of time zones in the world, even though that adds up to 39.

Because of the weird UTC +13:45, which is only for New Zealand’s Chatham Islands (population: 800) and only during daylight saving time, which is counted in both the 2nd and 3rd types. It’s a special offset time zone and a bonus time zone around the International Date Line.

By the way, daylight saving time is obviously very absurd. Governments love to get involved in every part of our lives, even our sleep schedule. And as with everything else, they make it worse, unsurprisingly. But that’s a whole other topic.

So anyway, let’s explain how to see all the time zones in the world on the color-coded map. You can play around with the full interactive version on Timeanddate.com too.

24 basic time zones (1 for each hour)

First, there are the obvious 24 basic 15-degree slices (UTC, UTC +1 to +12, and UTC -1 to -11).

Those are the main colors that roughly follow the longitudinal lines (orange, yellow, green, blue, purple, and red — 4 times each).

But of course, some governments didn’t want to keep things easy and follow 1-hour increments, that would be too simple.

11 special offset time zones (not in even 1-hour increments)

Second, there are the time zones that are offset by special increments of 30 minutes and 45 minutes (!!!) instead of a nice and even full 1-hour difference (8 have +0:30 and 3 have +0:45).

Those are the striped zones on the map.

For example, India is striped red and orange, because its time zone is UTC +5:30 (red is UTC +5, and orange is UTC +6). Canada’s own Newfoundland and Labrador is UTC -3:30 too.

4 bonus time zones (around the International Date Line)

Third, there are a few bonus time zones that exist because of the International Date Line (UTC -12, UTC +13, UTC +13:45, and UTC +14).

Those are all for islands in the Pacific obviously, so they aren’t very visible on that map unless you zoom in.

These exist to keep islands from being on different calendar days than other places with close links. That’s how Baker Island (USA) and Teraina (Kiribati) are so close by but have a massive 26-hour time difference.

Why all time zones in the world are based on UTC

Time zones are based on UTC, or Coordinated Universal Time.

UTC +0 (or just UTC alone) is Greenwich Meridian Time (GMT). It passes through the Royal Observatory in Greenwich, near London (in England, the United Kingdom, Great Britain, and the British Isles).

That’s obviously an arbitrary spot, but that was the center of the world for such a long time, so that’s how it still works (and one of the main reasons why most “Western” maps are centered there too).

Royal Observatory in Greenwich (photo credit: Daniel Case/Wikimedia Commons)

The 180° line of longitude is exactly opposite from the Greenwich Prime Meridian, in the Pacific Ocean.

The International Date Line, which separates calendar days, roughly follows it.

List of all time zones in the world

Here’s a list of all the time zones with a few of the areas they cover (and the time zones not part of the standard 24 are bolded):

UTC +0: British Isles, West Africa
UTC -1: Cabo Verde, Ponta Delgada (Portugal) and Ittoqqortoormiit (Greenland)
UTC -2: Sandwich Island (South Georgia)
UTC -3: South America and Greenland
UTC -3:30: St. John’s, Newfoundland and Labrador (Canada)
UTC -4: South America and Eastern Canada
UTC -5: South America, Eastern Canada and Eastern US
UTC -6: Central America, Central Canada and Central US
UTC -7: Western Mexico, Central Canada and Central US
UTC -8: Western Canada and Western US
UTC -9: Alaska (US)
UTC -10: French Polynesia, Kiribati, Cook Islands, Hawaii (US)
UTC -11: US Minor Outlying Islands and Niue
UTC -12: Pacific Islands
UTC +1: Western and Central Europe and Africa
UTC +2: Eastern Europe and Southern Africa
UTC +3: Western Russia and Middle East
UTC +3:30: Iran
UTC +4: Caucasus and Western Gulf
UTC +4:30: Afeghanistan
UTC +5: Central Asia, Pakistan, and part of Russia
UTC +5:30: India and Sri Lanka
UTC +5:45: Nepal
UTC +6: Bangladesh, Bhutan, and part of Russia
UTC +6:30: Myanmar and Cocos (Keeling) Islands
UTC +7: Part of Russia and part of Eastern Asia
UTC +8: Part of Asia and Western Australia
UTC +8:45: Australia (Eucla)
UTC +9: Part of Russia and Eastern Asia
UTC +9:30: Australia (Northern Territory, Broken Hill), Marquesas Islands (French Polynesia)
UTC +10: Part of Russia, Papua New-Guinea and Eastern Australia
UTC +10:30: Australia (South and Broken Hill)
UTC +10:30/+11: Lord Howe Island
UTC +11: Part of Russia and Oceania Islands
UTC +12: Part of Russia and Oceania Islands
UTC +12:45/+13:45: Chatham Islands (New Zealand)
UTC +13: Pacific Islands
UTC +14: Pacific Islands

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Summary

The number of time zones in the world is surprisingly high at 38, instead of the 24 that we would have if we kept things simple with just 24 zones, 1 for each of the 24 hours in a day. But many countries wanted offset times (for 30 or 45 minutes) and/or wanted to circumvent the International Date Line.