How Many Time Zones Are There in the World?
The school answer is 24. Count the local times people actually live by and you get about 38, and if you ask a computer, it'll list more than 400 named time zones. Strangely, all three numbers are right, because each one is counting something different.
Where 24 comes from
The Earth turns 360 degrees in 24 hours, or 15 degrees an hour. Cut the globe into 24 strips of 15 degrees, give each strip its own hour, and you've got the textbook map, with the middle strip centred on Greenwich in London, where Coordinated Universal Time (UTC) is measured from. (If UTC and GMT blur together for you, UTC vs GMT explained sorts that out.)
That tidy map lasted about as long as it took governments to look at it. Countries pick their own time to suit their trade, their capital or their neighbours, and a line of longitude rarely wins that argument.
About 38 actually in use
That's roughly how many different UTC offsets people live by at some point in the year. The extras come from two places.
Some countries sit on a half hour or even a quarter hour: India is UTC+05:30, Iran UTC+03:30, Nepal UTC+05:45, and New Zealand's Chatham Islands UTC+12:45. There's a separate guide on half-hour and 45-minute time zones.
The range is also wider than 24 hours. It runs from UTC−12, on two empty US islands in the Pacific, right up to UTC+14 in Kiribati, a 26-hour spread, which means that for two hours of every day three different dates are in use somewhere on Earth. The International Date Line guide explains how that works.
Daylight saving nudges the count around a little as well. When Europe or the US moves its clocks, nobody gets a new zone, but their offset changes for half the year, so the list of offsets "in use today" shifts slightly every spring and autumn.
Why your phone lists hundreds
Phones, laptops and calendar apps use the IANA time zone database, which has over 400 entries with names like America/Chicago or Asia/Kolkata. Each entry is a separate history rather than a separate offset. Two cities can share a clock today but have changed their clocks on different dates in the past, so the database keeps them apart, and that's how your calendar still gets a meeting from 1995 right.
France wins, which surprises people
France has 12 time zones, 13 for part of the year. It sounds wrong until you remember French Polynesia, New Caledonia, Réunion, French Guiana and the other overseas territories scattered across every ocean. The top of the list:
| Country | Time zones | Why so many |
|---|---|---|
| France | 12 | Overseas territories around the world |
| Russia | 11 | All on its own land, from Kaliningrad to Kamchatka |
| United States | 11 | Pacific and Caribbean territories |
| Australia | 9 | Mainland plus island territories |
| United Kingdom | 9 | Overseas territories |
| Canada | 6 | Newfoundland to the Pacific coast |
Russia is the impressive one, though. All 11 of its zones sit on one continuous piece of land, from UTC+2 in Kaliningrad to UTC+12 in Kamchatka, so when Moscow is having an early dinner, Kamchatka is already past midnight.
The US: 6, 9 or 11, depending who's counting
You'll see different answers online because people count different things.
- The 50 states use 6: Eastern, Central, Mountain, Pacific, Alaska and Hawaii-Aleutian.
- Add the territories where people live and it's 9, with Atlantic time for Puerto Rico and the US Virgin Islands, Samoa time for American Samoa, and Chamorro time for Guam and the Northern Mariana Islands.
- Count two uninhabited islands too and you reach 11: Baker and Howland at UTC−12 and Wake Island at UTC+12.
Most Americans only ever deal with the first four. Arizona adds a wrinkle: most of the state stays on Mountain Standard Time all year, so in summer it matches Los Angeles, while the Navajo Nation in the north-east does change its clocks. Hawaii skips daylight saving too. Both are allowed under the Uniform Time Act of 1966, which lets a state stay on standard time year-round but not on summer time. If the letters confuse you, EST vs EDT and PST vs PDT clears up which one to write.
Huge countries with a single clock
Size doesn't decide it. China is about as wide as the continental US but runs on Beijing time, UTC+8, from coast to coast. Out in Xinjiang the winter sun can rise after 9 AM, and many locals keep an unofficial clock two hours behind. India does the same on a smaller scale; why India has only one time zone covers that history and the long debate about a second zone.
The first place to see a new day
That's Kiribati's Line Islands, at UTC+14. Kiritimati (Christmas Island) is usually the first inhabited place to hit midnight and the first to celebrate New Year, while American Samoa, at UTC−11, finishes the same day close to 25 hours later. The live time is on the Kiribati time page.
What you actually need day to day
Hardly anyone needs the exact count. What matters is the gap between you and the other person and whether either of you is about to change clocks. For a single time, use the Time Zone Converter; for several cities, the Meeting Planner. The countries list shows the live local time everywhere, a bit like a world time map you can click.