This guide covers How Many Time Zones Are There? | TimeFlow — what it means, how it works, and how to use it. The explanations below are followed by worked examples with real dates and real times, a set of frequently asked questions, and links to the tools that do the calculation for you: the time zone converter, the world clock, and the UTC converter. Where a number is given — an offset, a date, a count — it is computed from the IANA Time Zone Database for the date stated, not copied from a table that may be out of date.

Try the tool: Time Zone Converter — convert any time between any two cities, with the daylight saving rules for the date you choose.

The short answer is that the world has 24 theoretical time zones and 38 actual UTC offsets in use. The two numbers answer different questions, and most of the confusion about 'how many time zones' comes from mixing them up.

The 24 comes from the geometry: the Earth turns 360 degrees in 24 hours, so each hour of time equals 15 degrees of longitude. If time zones were perfect slices, there would be exactly 24 of them, each one hour apart. The 38 comes from politics and geography. Governments draw time zone boundaries along borders, not along lines of longitude, and several countries use half-hour or 45-minute offsets. India (UTC+05:30), Nepal (UTC+05:45), Iran (UTC+03:30), Afghanistan (UTC+04:30) and parts of Australia (UTC+08:45, UTC+09:30, UTC+10:30) all break the one-hour pattern.

There is a third way to count: by named zone. The IANA Time Zone Database, which computers use, lists about 350 named zones — but many share the same offset and rules, so they are duplicates in practice. Counting named zones gives a much bigger number than counting offsets, and it is not a useful answer to the question most people are asking.

So the honest answer depends on what you mean. 24 hourly slices in theory. 38 different offsets in practice, from UTC−12:00 to UTC+14:00. And if you count the zones that are only in use for part of the year — because daylight saving moves them — the number of distinct offsets in use on any given day is smaller: around 37 in January and 38 in July, since a few zones only exist in summer.

In practice

The number changes during the year, which is the part most articles get wrong. In January, when the northern hemisphere is on standard time and the southern hemisphere is on daylight time, there are about 37 different offsets in use. In July the pattern flips and there are about 38. A few offsets exist only in summer — for example, the zones that move to UTC+13:00 or UTC+14:00 in the southern summer — so the count depends on the date you ask.

The extremes are worth knowing. The earliest time on Earth is UTC+14:00, used by Kiribati's Line Islands — the first places on the planet to see each new day. The latest is UTC−12:00, used by Baker Island, which is uninhabited. The total span is 26 hours, which is why a call between two people can be scheduled 'tomorrow' for one of them and 'today' for the other.

Counting by named zones gives a much larger number — around 350 in the IANA database — but that counts duplicates. America/New_York and America/Detroit follow the same rules, so they are the same zone in practice. The honest answers are 24 in theory, 38 offsets in practice, and about 350 named zones in the database. Use the offset count when you are explaining time zones, and the named-zone count when you are writing software.

The numbers: daylight saving in 2026

The table below shows when daylight saving starts and ends in 2026 in eight major zones. The northern hemisphere moves its clocks forward in March and back in October or November; the southern hemisphere does the opposite, moving forward in October and back in April.

Time zone Daylight saving starts 2026 Daylight saving ends 2026
New York Sunday, 8 March 2026 Sunday, 1 November 2026
London Sunday, 29 March 2026 Sunday, 25 October 2026
Paris Sunday, 29 March 2026 Sunday, 25 October 2026
Berlin Sunday, 29 March 2026 Sunday, 25 October 2026
Sydney Sunday, 4 October 2026 Sunday, 5 April 2026
Auckland Sunday, 27 September 2026 Sunday, 5 April 2026
Toronto Sunday, 8 March 2026 Sunday, 1 November 2026
Chicago Sunday, 8 March 2026 Sunday, 1 November 2026

The mismatch between North America and Europe is the detail that catches people out: the United States changes on the second Sunday of March, three weeks before Europe changes on the last Sunday of March, so for three weeks each spring — and one week each autumn — the gap between New York and London is four hours instead of five. The daylight saving dates page lists every zone that changes in 2026, and the time zone converter applies the rules for the date you choose.

The same eight zones in 2027:

Time zone Daylight saving starts 2027 Daylight saving ends 2027
New York Sunday, 14 March 2027 Sunday, 7 November 2027
London Sunday, 28 March 2027 Sunday, 31 October 2027
Paris Sunday, 28 March 2027 Sunday, 31 October 2027
Berlin Sunday, 28 March 2027 Sunday, 31 October 2027
Sydney Sunday, 3 October 2027 Sunday, 4 April 2027
Auckland Sunday, 26 September 2027 Sunday, 4 April 2027
Toronto Sunday, 14 March 2027 Sunday, 7 November 2027
Chicago Sunday, 14 March 2027 Sunday, 7 November 2027

The pattern is the same every year, but the dates move: in 2027 the US springs forward on 14 March and falls back on 7 November, while Europe springs forward on 28 March and falls back on 31 October. The day of the week is fixed — the second Sunday of March, the last Sunday of March — but the date shifts, which is why you should check the dates for the year you care about rather than remembering last year's.

Key facts

  • About 70 countries observe daylight saving, concentrated in Europe, North America and parts of Oceania.
  • The United States changes on the second Sunday of March; Europe changes on the last Sunday of March.
  • Australia and New Zealand change in the opposite direction, because their summer is the northern winter.
  • Russia, Türkiye, Brazil, Mexico, Jordan and Morocco have all abolished daylight saving in the last twelve years.
  • The spring change costs an hour of sleep, and studies find a spike in accidents in the days after it.

Frequently asked questions

How many time zones are there in the world?

24 in theory and 38 different UTC offsets in practice, from UTC−12:00 to UTC+14:00. The count changes slightly during the year because of daylight saving.

Why are there more than 24 time zones?

Because governments draw the boundaries along borders, and several countries use half-hour or 45-minute offsets — India (UTC+05:30), Nepal (UTC+05:45), Iran (UTC+03:30).

How many time zones does the IANA database list?

About 350 named zones, but many share the same offset and rules, so they are duplicates in practice. Counting named zones gives a much bigger number than counting offsets.

What is the earliest time zone?

UTC+14:00, used by Kiribati's Line Islands — the first places on Earth to see each new day. The latest is UTC−12:00, used by the uninhabited Baker Island.

Does the number of time zones change during the year?

Yes. A few offsets exist only in summer, so there are about 37 offsets in use in January and about 38 in July.

When does daylight saving start in 2027?

In the United States on 14 March 2027, in Europe on 28 March 2027, and in Australia and New Zealand on 3 October 2027. The daylight saving dates page lists every zone that changes.

What is the time difference between London and Tokyo?

Nine hours in January 2026: London is UTC+00:00 and Tokyo is UTC+09:00. In July it is eight hours, because London moves to UTC+01:00 while Tokyo stays on UTC+09:00. The time zone converter gives the difference for any two cities and any date.

Related pages

Sources

  • IANA Time Zone Database, via Node.js Intl (Intl.DateTimeFormat with timeZone) — offsets, daylight saving dates and local times in this article were worked out from the IANA database, not typed from memory.
  • TimeFlow's own time-zone data (data/cities.ts, data/dst.ts), computed from the IANA database.
  • Time zone rules and offsets: the IANA Time Zone Database, as applied by this site's tools. Offsets and daylight saving dates on this page are computed from the database for the dates stated.
  • TimeFlow's time zone converter, world clock and UTC converter — the live tools behind the numbers on this page.
  • Time-zone and daylight saving rules are set by governments and can change. For flights, deadlines and meetings that cannot move, confirm the time with an official source.