Time zones and clocks
Daylight saving time explained: who changes their clocks, when, and why
Daylight saving time is the practice of setting clocks forward for part of the year so that evenings get more daylight. Less than half the world does it, and the ones that do rarely agree on the date.
Last reviewed October 5, 2026About 4 min to readSite version v2026.10.1
What actually happens at the changeover
On the spring changeover, clocks jump forward, usually by one hour, so a time such as 2:00 AM is skipped and the day has 23 hours. On the autumn changeover they fall back, so an hour is repeated and the day has 25. The zone's UTC offset changes with it: New York moves from UTC-5 to UTC-4 in March and back in November.
Nothing about the sun changes. The sun still rises when it rises; the clock reading attached to that moment is what moves. Sunrise at 6:30 becomes sunrise at 7:30, and sunset at 7:00 becomes sunset at 8:00. The idea, first adopted nationally by Germany and Austria-Hungary on April 30, 1916 as a wartime fuel measure, is to shift waking hours toward the daylight.
Who observes it
Most of Europe, most of North America, and a handful of countries elsewhere. Most of Africa and Asia do not: India, China, Japan, Indonesia, and the whole of the Middle East apart from a few countries keep one offset all year. Near the equator the length of the day barely changes across the year, so there is nothing to save.
Even inside countries that observe it, there are holdouts. In the United States, Hawaii and most of Arizona stay on standard time all year, while the Navajo Nation inside Arizona does change. In Australia, New South Wales, Victoria, Tasmania, South Australia and the Capital Territory change; Queensland, Western Australia and the Northern Territory do not. In Canada, most of Saskatchewan stays on Central Standard Time year-round.
Several countries have stopped in recent years. Mexico abolished seasonal changes nationally in October 2022, keeping them only in some municipalities along the United States border. Iran stopped in 2022. Others have gone the other way: Egypt reinstated summer time in 2023. The country pages say which case applies to each place, computed from the time zone database rather than from a list that could go stale.
The dates differ by region
| Region | Clocks go forward | Clocks go back | Local change time |
|---|---|---|---|
| United States and Canada (most areas) | Second Sunday in March | First Sunday in November | 2:00 AM local in each zone |
| European Union, United Kingdom, Switzerland, Norway | Last Sunday in March | Last Sunday in October | 01:00 UTC everywhere at once |
| Australia (observing states) | First Sunday in October | First Sunday in April | 2:00 AM local standard time |
| New Zealand | Last Sunday in September | First Sunday in April | 2:00 AM local standard time |
| Chile (most of the country) | First Sunday in September | First Sunday in April | Midnight local |
Two details catch people out. First, Europe changes everything at the same instant, 01:00 UTC, so Lisbon changes at 1 AM local, London at 1 AM, Paris at 2 AM and Helsinki at 3 AM. North America changes at 2 AM in each zone, so the change ripples across the continent over three hours. Second, the United States has been on its March-to-November rule only since 2007; older documents and some software still describe the earlier April-to-October rule.
Rules are set by governments and change with short notice, so do not memorise the table. Each city page and country page carries a "when the clocks change" table computed for the current and next year from the live time zone database.
North and south run opposite
Summer time follows summer, and summer is December to February south of the equator. So while New York is on standard time in January, Sydney is on daylight time, and the gap between them is different in January and in July. The PST to AEST chart is a good example: the difference between Los Angeles and Sydney swings by two hours across the year because the two cities change in opposite directions.
There are also a few weeks each spring and autumn when one side has changed and the other has not yet. Any time difference you looked up in February can be wrong by an hour in late March. The converter on the home page resolves both zones for the actual date you pick, which is the only reliable way through those weeks.
Will it be abolished?
The European Parliament voted in 2019 to end seasonal changes, but member states never agreed on which time to keep, and the proposal has not become law. In the United States, bills to make daylight time permanent come up regularly in Congress and had not been enacted when this guide was last reviewed. Both regions still change their clocks twice a year.
Whatever happens, the rule that matters is the one in your device's time zone database on the day in question. World Time Lab reads that database rather than guessing at future legislation, so if a change is announced, your clocks here will follow as soon as your operating system or browser updates.
See it on the site
- Time in the United StatesEvery US zone with its live clock and the exact March and November changeover dates.
- Time in AustraliaSee which states change and which do not, side by side.
- Meeting time finderPick a real date and let the planner resolve daylight saving for every participant.