This guide covers History of Standard Time | 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a count — it is computed from the IANA Time Zone Database for the date stated, not copied from a table that may be out of date.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.

Standard time — the idea that a whole region uses one clock time — is only about 180 years old. Before it, every town kept local solar time, set by the Sun. Bristol was 10 minutes behind London, and a traveller going from one town to the next had to reset their watch at every stop.

The railway broke the system. Trains ran on timetables, and a timetable cannot work if every station has a different time. In 1840 the Great Western Railway in Britain adopted London time for all its stations — 'railway time' — and by 1855 most of Britain's railways had followed. In 1880 the UK made Greenwich Mean Time the legal standard, the first country to do so.

The idea spread by telegraph and by conference. In 1883 the American railways adopted four standard time zones, and in 1884 the International Meridian Conference in Washington chose Greenwich as the world's Prime Meridian and divided the world into 24 hourly zones. The system was not law everywhere at once — France kept Paris time until 1911, and some countries held out for decades — but by the early 20th century, standard time was the norm.

The last step was precision. In 1972 UTC replaced GMT as the formal standard, based on atomic clocks rather than the Sun. And in the 1990s GPS made precise time available everywhere on Earth. Standard time began as a railway convenience; it is now the invisible infrastructure of the modern world.

In practice

Standard time was invented by the railways, and the man usually credited is Sir Sandford Fleming, a Scottish-born Canadian engineer who proposed a worldwide system of standard time in 1879 after missing a train in Ireland because the timetable was printed in local time. His proposal — 24 time zones, each one hour apart, measured from a prime meridian — was the system the world eventually adopted.

The International Meridian Conference of 1884 chose Greenwich as the prime meridian, and the world divided into time zones over the following decades. Britain adopted Greenwich Mean Time by law in 1880; the United States adopted standard time in 1883, when the railways imposed it; and the rest of the world followed, though the process took decades — China did not adopt a single time zone until 1949, and India until 1947.

The system is still changing. Governments move their clocks, abolish daylight saving, and change their offsets — Morocco abolished daylight saving in 2026, British Columbia moved to permanent Pacific Time in the same year — and the IANA Time Zone Database records every change. Standard time is not a finished system; it is a living one, and it changes every year.

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

Who invented standard time?

Sir Sandford Fleming, a Scottish-born Canadian engineer, proposed a worldwide system in 1879 after missing a train in Ireland because the timetable was printed in local time.

When was standard time adopted?

The International Meridian Conference of 1884 chose Greenwich as the prime meridian. Britain adopted GMT by law in 1880; the United States adopted standard time in 1883.

Why was Greenwich chosen as the prime meridian?

Because Britain was the world's greatest maritime power, most ships already used Greenwich for navigation, and the Royal Observatory had published nautical tables for a century.

When did China adopt a single time zone?

In 1949. China spans five geographical time zones and uses one — Beijing time — for the whole country.

Is standard time still changing?

Yes. Governments move their clocks and abolish daylight saving regularly — Morocco abolished it in 2026, and British Columbia moved to permanent Pacific Time in the same year.

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.