Daylight saving time

Daylight saving time (DST) means moving the clocks forward one hour in spring and back one hour in autumn. The easy way to remember it is "spring forward, fall back".

The change doesn't create any extra daylight. It shifts an hour of daylight from the early morning, when most people are asleep, to the evening, when they're awake. In summer, sunsets come an hour later by the clock.

Benjamin Franklin joked about making better use of morning daylight in 1784, but the first serious campaign came from William Willett, a British builder, in 1907. He wanted clocks moved forward in four 20-minute steps each April and back again in September.^[1]

It took a war to make it happen. Germany and Austria-Hungary moved their clocks forward on April 30, 1916, to save coal for the war effort, and Britain followed within weeks.^{[1, 2]} Many other countries have used it since, dropped it, and sometimes brought it back.

Daylight saving time is mostly used far from the equator, where the length of the day changes a lot between summer and winter. Near the equator, days are about the same length all year, so there's little to gain.

• Most of Europe and the United States use it. In the US, Hawaii and most of Arizona stay on standard time all year.^[3]
• Parts of the southern hemisphere use it too, including New Zealand, Chile and southeastern Australia. Queensland, Western Australia and the Northern Territory don't.^{[6, 7, 8]}
• Most of Asia and Africa keep the same time all year. Mexico stopped using daylight saving time in 2022, except in towns along the US border.^[9]

Every country sets its own dates, so the clocks don't change everywhere on the same day. These are the rules for some of the places most people ask about:

• United States: forward on the second Sunday in March, back on the first Sunday in November, both at 2:00 a.m. local time.^[3]
• United Kingdom: forward at 1:00 a.m. on the last Sunday in March, back at 2:00 a.m. on the last Sunday in October.^[4]
• European Union: the last Sunday in March and the last Sunday in October, at 01:00 UTC. Every EU country changes at the same moment, whatever its local time.^[5]
• Australia (where used): forward on the first Sunday in October, back on the first Sunday in April.^[6]
• New Zealand: forward on the last Sunday in September, back on the first Sunday in April.^[7]

Notice that the southern hemisphere does it the other way round. When it's summer in Sydney, it's winter in London, so their clocks move in opposite directions.

Because places change on different dates, or not at all, the time difference between two cities isn't fixed through the year:

• New York and London are usually five hours apart. But the US changes its clocks a few weeks before the UK in March and a week after it in autumn, so for those weeks the gap is four hours.^{[3, 4]}
• London and Sydney move in opposite directions, so the gap swings between 9 hours in the northern summer and 11 hours in the northern winter.
• Tokyo doesn't use daylight saving time at all, so its gap to New York or London shifts by an hour twice a year.

This is the most common reason a recurring meeting suddenly lands at the wrong time. TimeZonar's world clock shows a notice two weeks before a city's clocks change, and the guide to scheduling across time zones explains how to plan around it.

On the spring change, one hour disappears: in the US, the clock goes from 1:59 a.m. straight to 3:00 a.m. On the autumn change, one hour happens twice: the clock reaches 1:59 a.m., goes back to 1:00 a.m., and runs through that hour again.^[3]

Phones and computers change automatically. Older ovens, car clocks and wall clocks usually need changing by hand. If you have an early flight or alarm on a change date, double-check the time the night before.

Possibly. In 2019, the European Parliament voted to end the twice-yearly clock changes, but EU countries couldn't agree on whether to stay on summer or winter time, and the plan has stalled.^[10]

In the United States, the House of Representatives passed the Sunshine Protection Act in July 2026, which would keep the country on daylight saving time all year. It still needs to pass the Senate and be signed into law before anything changes.^[11]

Until then, the clocks keep changing. For how daylight saving fits into the bigger picture of offsets and time zone rules, read how time zones work.

1. 1.Royal Museums Greenwich, When do the clocks go forward?. Benjamin Franklin's 1784 joke, William Willett's campaign, and the UK's Summer Time Act of 1916.
2. 2.The Western Front Association, Spring forward, fall back: the changing of the clocks and the First World War. Germany and Austria-Hungary starting daylight saving on April 30, 1916 to save coal.
3. 3.U.S. Department of Transportation, Daylight Saving Time. US change dates and times, and the places that stay on standard time.
4. 4.GOV.UK, When do the clocks change?. UK change dates and times.
5. 5.EUR-Lex, Directive 2000/84/EC on summer-time arrangements. EU change dates, all at 01:00 UTC.
6. 6.NSW Communities and Justice, Daylight saving. Australian change dates and the states that take part.
7. 7.New Zealand Government, Daylight saving. New Zealand change dates.
8. 8.IANA, Time Zone Database. Current daylight saving rules for other countries, such as Chile.
9. 9.Bloomberg Línea, Mexico abolishes daylight saving time. Mexico ending daylight saving in 2022.
10. 10.The Local, Whatever happened to the EU plan to ditch the changing of the clocks?. The European Parliament's 2019 vote and why the plan stalled.
11. 11.NBC News, House passes bill that would make daylight saving time permanent. The House vote on the Sunshine Protection Act in July 2026.