Find the time difference between any two cities in the world
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London
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New York
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Best time to call
Overlap when both cities are within 9am–6pm working hours
London
Good time to call
New York
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Common time differences
How is the time difference calculated?
The time difference between two cities is calculated by finding each
city's UTC offset — the number of hours and minutes it is ahead of or
behind Coordinated Universal Time — and subtracting one from the other.
The result tells you exactly how many hours separate the two clocks
right now.
That difference can change throughout the year. Daylight saving time
shifts clocks forward or back in many countries at different dates,
meaning the gap between cities like London and New York changes from
5 hours in winter to 4 hours in summer. Clockr recalculates
automatically whenever DST rules apply.
Clockr uses IANA timezone identifiers and the browser's
Intl.DateTimeFormat API to handle all daylight saving rules for over
250 cities without any manual adjustment. Select any two cities above
and the difference, live clocks, and best-time-to-call overlap all
update instantly.
Frequently asked questions
What is the time difference between London and New York?
London is typically 5 hours ahead of New York in winter (GMT vs
EST) and 4 hours ahead in summer (BST vs EDT). The exact
difference depends on when each city switches to and from daylight
saving time. Select London and New York above to see the live
difference right now.
What is the time difference between the UK and Australia?
The UK and Australia span multiple time zones, so the difference
varies by city. London is typically 9 to 11 hours behind eastern
Australian cities like Sydney and Melbourne, depending on daylight
saving in both countries. Western Australia (Perth) is around 7 to
8 hours ahead of London.
What is the time difference between Dubai and the UK?
Dubai (UAE Standard Time) is 4 hours ahead of London during UK
winter (GMT) and 3 hours ahead during UK summer (BST). The UAE
does not observe daylight saving time, so the gap narrows by one
hour when the UK clocks go forward in March.
Why does the time difference between cities change in summer?
Daylight saving time moves clocks forward by one hour in spring
and back in autumn in many countries — but not all, and not on the
same dates. When one city observes DST and another does not, or
they switch on different weekends, the gap between them changes.
Clockr handles these shifts automatically using IANA timezone data.
What is the largest time difference between two places on Earth?
The maximum offset from UTC is ±14 hours, so the largest possible
difference between two inhabited places is 26 hours — though in
practice the biggest gaps are around 25 hours. For example, Baker
Island (UTC−12) and Kiritimati in Kiribati (UTC+14) are on
opposite sides of the International Date Line.
What is the best time to schedule a meeting between the US and UK?
The overlap window is typically 2:00 PM–5:00 PM GMT (9:00 AM–12:00
PM EST) on weekdays — when both London and New York are within
standard working hours. Use the "Best time to call" timeline above
to see the exact overlap for your chosen cities, which updates in
real time.
How many hours ahead is Japan compared to the UK?
Japan Standard Time is 9 hours ahead of London during UK winter
(GMT) and 8 hours ahead during UK summer (BST). Japan does not
observe daylight saving time, so the gap is always either 8 or 9
hours depending on the UK's DST schedule.
What time zone should I use for international emails?
Always include a time zone when scheduling across borders — UTC
(GMT) is the safest neutral reference, or specify the recipient's
local time with the city name (e.g. "3:00 PM GMT / 10:00 AM EST").
Avoid ambiguous phrases like "tomorrow morning" without a zone.
Tools like this calculator help you convert before you send.