This guide covers Why Do Clocks Go Forward? | 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a count — it is computed from the IANA Time Zone Database for the date stated, not copied from a table that may be out of date.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 clocks go forward in spring so that daylight falls in the evening instead of the early morning. In June the Sun rises around 4:45am in London — before almost anyone is awake — and sets around 9:20pm. If the clocks stayed on winter time, the Sun would rise at 3:45am and set at 8:20pm: an hour of daylight would be wasted while people slept, and the evening would be an hour shorter.

The idea was first proposed seriously by William Willett, a British builder, in 1907. He noticed that Londoners were asleep through the best part of summer mornings and argued that moving the clocks would save daylight — and, he calculated, save the country money on lighting. His pamphlet, 'The Waste of Daylight', was mocked at first, but Germany adopted the idea in 1916 during the First World War to save coal, and Britain followed weeks later.

The energy-saving argument was always the official justification: less artificial light in the evening means less electricity. Modern studies are mixed — air conditioning and modern lighting have changed the maths, and some studies find the savings are now negligible or even negative. The reason the clock change survives is more about lifestyle: people like light evenings, and the retail, sport and leisure industries like them too.

The cost is real. The spring change costs everyone an hour of sleep, and studies consistently find a spike in road accidents, heart attacks and workplace injuries in the days after the clocks go forward. That is why the debate never ends — and why several countries, including Mexico and Brazil, have abolished the change altogether.

In practice

The arithmetic is simple. In London in June, the Sun rises around 4:45am and sets around 9:20pm on summer time. On winter time it would rise at 3:45am — while almost everyone is asleep — and set at 8:20pm, cutting an hour off the evening. Moving the clocks forward does not create daylight; it moves an hour of it from the morning, when it is wasted, to the evening, when it is used.

William Willett, the man who proposed the change in Britain, was a builder who liked to ride his horse in the early morning and noticed how much daylight was being wasted while London slept. His 1907 pamphlet, 'The Waste of Daylight', calculated that the change would save the country money on lighting — and he spent the rest of his life campaigning for it. He died in 1915, a year before Britain adopted it, so he never saw his idea become law.

The counter-argument is about mornings. The same change that gives light evenings takes light from the morning, so children walk to school in the dark and the first hour of the working day is darker. In far northern countries the trade-off is worse: in Scotland, the winter mornings are already dark, and permanent summer time would mean sunrise after 9am. That is the core of the debate — evenings against mornings — and it is why no country has found a change that pleases everyone.

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

Why do the clocks go forward in spring?

So daylight falls in the evening instead of the early morning. In June the Sun rises around 4:45am in London — before almost anyone is awake — and moving the clocks forward moves an hour of daylight to the evening.

Who proposed daylight saving?

William Willett, a British builder, in his 1907 pamphlet 'The Waste of Daylight'. Germany adopted it first, in 1916, to save coal during the First World War, and Britain followed weeks later.

Does the spring change cause problems?

Yes. Studies consistently find a spike in road accidents, heart attacks and workplace injuries in the days after the clocks go forward, because everyone loses an hour of sleep.

Why do people like light evenings?

Because the extra hour of evening daylight is used for sport, shopping and social life, while the hour of morning daylight it replaces falls while most people are asleep.

What is the argument against it?

The change takes light from the morning, so children walk to school in the dark, and the energy savings are now disputed. Several countries have abolished it altogether.

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.