Time zone converter
A time in one place, in another. With the gap checked against the one that holds in midwinter — so the weeks when a country has moved its clocks and its counterpart has not are named rather than left to be discovered in a calendar invitation.
By Alex Seote, Built and maintains Rule Calculator
Offsets read live from the IANA database · How we check
In London
Tue, Mar 10, 2026, 01:00 PM
London is 4 hours ahead of New York on this date. UTC−04:00 against UTC+00:00.
On this date only the first zone has its clocks forward, so the gap is 4 hours rather than the 5 it is in midwinter. This is the window that breaks recurring meetings.
A working day, side by side
| New York | London |
|---|---|
| 8:00 | Tue 12:00 PM |
| 9:00 | Tue 1:00 PM |
| 10:00 | Tue 2:00 PM |
| 11:00 | Tue 3:00 PM |
| 12:00 | Tue 4:00 PM |
| 13:00 | Tue 5:00 PM |
| 14:00 | Tue 6:00 PM |
| 15:00 | Tue 7:00 PM |
| 16:00 | Tue 8:00 PM |
| 17:00 | Tue 9:00 PM |
| 18:00 | Tue 10:00 PM |
When each zone next moves its clocks
- New York: Sunday, November 1, 2026 — clocks go back by 1 hour, to UTC−05:00.
- London: Sunday, March 29, 2026 — clocks go forward by 1 hour, to UTC+01:00.
The gap is not a constant
“New York is five hours behind London” is true in January and false for about a month of the year. The two change their clocks three weeks apart in the spring and one week apart in the autumn, and in those windows the difference is four hours or six. Every converter that stores a number of hours instead of two offsets is wrong on those days, and none of them says so.
The southern hemisphere inverts the whole thing: Sydney is on summer time in January and standard time in July, so its gap to London swings by two hours across the year rather than one. The table above is computed from both zones' offsets at the actual instant, which is the only way to get those cases right.
Questions people actually ask
- Why did my recurring meeting move by an hour?
- Because the two countries change their clocks on different dates. The US goes forward on the second Sunday in March and back on the first Sunday in November; the EU and the UK go forward on the last Sunday in March and back on the last Sunday in October. Between those dates the gap between New York and London is four hours instead of five, and a meeting pinned to one side of it arrives an hour out on the other. The converter above says so on the dates it applies.
- Which countries do not change their clocks at all?
- Most of the world, by population. Japan, China, India, most of Africa, and all of the tropics keep one offset year-round, because the length of the day barely changes near the equator and there is nothing to shift. Within the US, Hawaii and most of Arizona stay on standard time. The page reports "does not change its clocks" rather than inventing a transition date.
- Is India really half an hour off?
- Yes — UTC+05:30, and it is not alone. Iran is at +03:30, Afghanistan at +04:30, and parts of Australia at +09:30. Nepal goes further and sits at +05:45. Any converter built on whole-hour arithmetic gets all of them wrong, which is why the offsets here come from the zone database rather than a number of hours.
- What is the difference between EST and EDT?
- EST is the winter offset, UTC−05:00; EDT is the summer one, UTC−04:00. Writing "EST" in June is the single commonest way a meeting invitation goes wrong, because the sender means "Eastern time" and the abbreviation means something specific and different. Naming the city rather than the abbreviation avoids it entirely.
- Do the clock-change rules ever change?
- Several times a year, somewhere. Countries move dates, adopt or abandon summer time, and occasionally change offset outright. That is why this page reads the platform’s copy of the IANA database at the moment you use it instead of shipping a table of offsets — a table would be right on the day it was written and quietly wrong afterwards.