Time difference calculator
On 14 October 2026, London is 5 hours ahead of New York. From 25 October the gap is 4 hours, because Britain puts its clocks back a week before the United States does — and that is the week transatlantic calls arrive an hour early.
Result+5 h
The gap is 5 h today, but 4 h from October 25, 2026, when London changes its clocks and the other side does not.
Trip Card
This trip only: the numbers it produced, the limits and tariffs it was checked against, and when those were checked. Print it or send it to whoever is travelling with you.
| Local time where you are — New York | 09:00 -04:00 |
|---|---|
| Local time there — London | 14:00 +01:00 |
| Difference | 5 h |
| Next clock change | October 25, 2026 |
Sources: IANA tzdata (418 zones, runtime ICU) (checked September 19, 2026)
Trip Card generated on September 20, 2026
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What the tool answers
Pick two places and a moment in the first one. The result gives the same instant in both, each with its UTC offset, the difference in hours, and — the part that is usually missing — whether that difference is about to change and on what date.
The offsets are read for the specific date you enter, not for today. A meeting being planned for late October is exactly the case where “London is five hours ahead” stops being true, and a tool that answers for the current moment answers the wrong question.
Reading the offsets
A label like −04:00 means four hours behind UTC. New York moves between −05:00 in winter and −04:00 in summer; London between +00:00 and +01:00. The difference between two places is simply the difference between their offsets at that instant, which is why it can be a whole number one week and not the next.
Half-hour and quarter-hour zones
Not every offset is a whole hour. India runs at +05:30, Newfoundland at −03:30, Nepal at +05:45, parts of Australia at +08:45. The difference shown here keeps the minutes rather than rounding them away, and the same applies to the arrival times in the flight tools that share this clock.
What this means in United States
The United States puts its clocks back on the first Sunday in November, a week after Europe does on the last Sunday in October. For that one week the gap between New York and London is four hours instead of the usual five — which is exactly the week people schedule calls wrong.
Questions people actually ask
- Why does the difference between New York and London change for a week?
- The two sides change clocks on different dates. The European Union and the United Kingdom end summer time on the last Sunday in October; the United States ends daylight saving on the first Sunday in November. In the days between, the usual five-hour gap is four — and calendar invitations sent before the change quietly land an hour out.
- Does it handle places with no daylight saving?
- Yes, and there are more of them than most schedules assume. Most of Asia, almost all of Africa, and Arizona within the United States never change their clocks, so their difference from Europe moves twice a year without anything happening locally at all.
- Where does the time zone data come from?
- From the IANA time zone database, the same source operating systems use, read through the runtime's own internationalisation data. That means historical and future transitions come from the maintained database rather than from a fixed offset table, which is the usual way a "UTC+1" assumption goes wrong.
- Can I share the result?
- Yes — the link carries the two cities and the date, so whoever opens it sees the same case rather than their own local time. That is the point of it: a time difference is almost always being settled between two people.
Where these numbers come from
Last checked:
- IANA time zone database, via the runtime's ICU data — September 19, 2026
In the United States baggage allowances are the carrier's own contract of carriage; the Department of Transportation requires the fees to be published, not harmonised, so two airlines on the same route can measure the same suitcase differently.
These figures are guidance, not a quotation. Airline allowances, gate fees and toll tariffs change; check the carrier or the road operator before you travel.