Dates and Days

Time zone converter

What a time in one place is in another

The gap between two places is not a fixed number — it changes for a few weeks each year when one side has moved its clocks and the other has not. This computes the offset for the actual date, and says so when a time does not exist or happens twice.

Converted time— Date there— Difference— From zone— To zone—
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The same instant — in a few places at once
PlaceLocal timeDateOffset

An offset is not a property of a place

“New York is UTC-5” is true for about four months of the year and false for the rest, when it is UTC-4. The same goes for most places that observe daylight saving, and roughly a third of the world does not observe it at all. So the question “what is the offset of this zone” has no answer without a date attached, and a converter that stores one number per zone is wrong for part of every year. This page asks the browser for the offset at the specific instant you gave it.

The fortnight when everything goes wrong

The United States moves its clocks in the second week of March; Europe moves in the last week of the same month. For those two or three weeks New York and London are four hours apart rather than the usual five, and every recurring meeting between them lands an hour out. The same thing happens in reverse in the autumn, when the US moves in early November and Europe moved in late October. Southern-hemisphere zones shift in the opposite season again, so an Australian meeting slot drifts twice a year against both.

Two hours a year that are genuinely strange

When clocks go forward an hour is deleted. On 8 March 2026 in New York the clock reads 01:59 and then 03:00, and there is no 02:30 at all — so a meeting invitation for 02:30 that morning refers to nothing. When clocks go back an hour repeats: on 1 November 2026 01:30 happens twice, an hour apart, once on summer time and once on standard. Most converters answer both cases without comment. This one names them, because in the first case the time you were given is wrong and in the second it is incomplete.

Where the data comes from, and why not from us

The rules change several times a year, at the discretion of governments and often with only weeks of notice. A copy of the database bundled into this page would be accurate on the day it shipped and would then go quietly wrong, with no symptom a reader could see. Every browser already carries the IANA database and updates it with the browser, so this page reads that instead. Nothing is downloaded, nothing is sent, and the answers are exactly as current as the browser giving them.

Questions

What time is 2pm New York in London?
Pick the two zones above and the answer appears with the date, because the answer is often on a different day. The gap between two places is not a fixed number: New York and London are five hours apart for most of the year but four hours apart for about two weeks in March and one in late October, because the two put their clocks forward on different dates. That is exactly the fortnight in which meetings get missed.
Why does the gap between two cities change during the year?
Because daylight saving does not start and end on the same date everywhere, and about a third of the world does not observe it at all. The United States moves in March and November, Europe in late March and late October, Australia in October and April. For the weeks when one has changed and the other has not, the difference between them is an hour off its usual value. This page computes the offset for the specific date you give it rather than treating it as a constant, which is the single commonest error in this kind of tool.
What happens if I pick a time that does not exist?
It tells you. When clocks go forward an hour is skipped entirely: on 8 March 2026 in New York there is no 02:30, the clock goes straight from 01:59 to 03:00. Most converters silently return something anyway. This page says the time does not exist in that zone and refuses to convert it, which is the honest answer and the useful one, because it means the time you were given was wrong.
What about the hour that happens twice?
It says that too. When clocks go back an hour repeats, so on 1 November 2026 in New York 01:30 occurs twice — once on summer time and once on standard time. They are two different instants an hour apart. This page converts using the first of them and flags the ambiguity, so you know the answer depends on which one was meant. A converter that says nothing has silently picked one for you.
Where does the time zone data come from?
Your own browser. Every browser ships the IANA time zone database and updates it along with the browser, so this page reads that rather than carrying a copy of its own. The rules change several times a year, whenever a government decides to move or abolish daylight saving, and a copy bundled into a page would be right on the day it was built and quietly wrong afterwards with no visible symptom. Reading the platform's database means the answers are as current as the browser is, and nothing is sent anywhere to get them.