Compare Time Zones: Side-by-Side Converter and Difference Calculator (2026)

Q: What is the time zone difference between New York and London?

5 hours most of the year. It briefly drops to 4 hours for about two weeks each March, because the US starts DST before the UK.

Q: Why does the time difference between two cities change during the year?

Daylight saving time. Cities switch on different dates and the Southern Hemisphere moves in the opposite direction, so gaps stretch and shrink by 1–2 hours.

Q: How do I compare 3 or more time zones at once?

Use a world clock view: put all cities in one row, slide to a candidate hour, and check every city stays inside working hours.

See what time it is in two or more cities at once, calculate the exact difference, and find hours that work for everyone.

To compare two time zones, take the difference between their UTC offsets. New York (UTC-4 in summer) and London (UTC+1) are 5 hours apart; London and Tokyo (UTC+9) are 8. Offsets change with daylight saving — the NY–London gap is 5 hours most of the year but 4 during two weeks in March. The converter below handles all of it automatically.

From

Date

Time

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Pick a source and target zone

How to compare two time zones

Pick the two cities (not just the zone abbreviation — "CST" means three different things).
Find each city's current UTC offset, including DST if active.
Subtract the offsets. Tokyo (UTC+9) minus New York (UTC-4) = 13 hours; when it's 09:00 in NY it's 22:00 in Tokyo the same day.
Check the date line: comparisons across the Pacific often land on different calendar days. Sydney is "tomorrow" relative to Los Angeles most of the time.

Or skip the arithmetic: select both cities in the tool above and read the live side-by-side result. The tool automatically accounts for daylight saving time on both sides.

Time difference table: 10 major cities

Difference relative to New York (July 2026, DST in effect):

City	Zone (IANA)	UTC offset	vs New York
Los Angeles	America/Los_Angeles	UTC-7	−3 h
New York	America/New_York	UTC-4	0
São Paulo	America/Sao_Paulo	UTC-3	+1 h
London	Europe/London	UTC+1	+5 h
Madrid / Paris / Berlin	Europe/Madrid	UTC+2	+6 h
Cairo	Africa/Cairo	UTC+3	+7 h
Dubai	Asia/Dubai	UTC+4	+8 h
Mumbai	Asia/Kolkata	UTC+5:30	+9:30 h
Tokyo	Asia/Tokyo	UTC+9	+13 h
Sydney	Australia/Sydney	UTC+10	+14 h

Note the half-hour offset in India (UTC+5:30) — and Nepal even uses UTC+5:45. Never assume differences are whole hours.

Why the difference changes during the year (DST)

Daylight saving time makes the gap between two cities variable:

Pair	Most of the year	Exception window
New York – London	5 h	4 h during ~2 weeks in March (US changes first)
New York – Sydney	14–16 h	Hemispheres shift in opposite directions
London – Tokyo	8 h (summer) / 9 h (winter)	Japan has no DST
Madrid – Mexico City	8 h	Mexico abolished DST in 2022

Rules also change by law with little notice — Egypt, Chile and Mexico have all changed DST policy in the last decade. That's why this converter uses the IANA time zone database instead of fixed offsets. Check current time and DST status per city on our live pages: London, New York, Tokyo.

Best overlap hours for meetings

Standard business hours (09:00–17:00 local) overlap as follows:

Pair	Overlap (local times)	Window
New York – London	09:00–12:00 NY = 14:00–17:00 London	3 hours
New York – Los Angeles	12:00–17:00 NY = 09:00–14:00 LA	5 hours
London – Tokyo	09:00–10:00 London = 17:00–18:00 Tokyo	1 hour
New York – Sydney	none within 9–17	needs flexibility

Rule of thumb: less than 7 hours apart = same-day meetings are easy; 7–11 hours = one side works early or late; 12+ hours = alternate who takes the inconvenient slot. For recurring international meetings, see the meeting planner guide.

Comparing more than two zones

For 3+ participants, comparing pairs quickly becomes error-prone. Instead:

Convert everyone to UTC as the common reference.
Write each person's working window in UTC (NY 13:00–21:00 UTC, London 08:00–16:00 UTC, Tokyo 00:00–08:00 UTC).
Look for the intersection — in this example NY–London share 13:00–16:00 UTC, but Tokyo doesn't overlap either. Someone flexes.

Our world clock shows all your cities in one row, which makes the intersection visible at a glance. Developers can normalize everything through a unix timestamp converter — epoch time is time-zone-free by design.

UTC offsets vs time zone names

UTC offset (UTC-5): a snapshot. Valid only at one moment of the year.
Abbreviation (EST, CST): ambiguous. CST = Central US, China Standard or Cuba Standard time.
IANA name (America/New_York): the full ruleset — offset, DST dates, historical changes. This is what software should store.

When someone says "the call is at 15:00 EST" in July, they usually mean EDT (UTC-4). A one-hour misunderstanding hidden in two letters — one more reason to share meeting times as city names or UTC. See the full list of time zone abbreviations and the difference between UTC and GMT.

Frequently asked questions

How do I compare two time zones?

Subtract their UTC offsets on the date you care about. London (UTC+1 in summer) vs Tokyo (UTC+9) = 8 hours difference. Or select both cities in the converter above and read the live side-by-side comparison.

What is the easiest way to compare time zones for a meeting?

Convert every participant's working hours to UTC and look for the overlap. For New York, London and Berlin the shared window is roughly 13:00–16:00 UTC (9–12 NY, 14–17 London, 15–18 Berlin).

Why does the time difference between two cities change during the year?

Daylight saving time. Cities switch on different dates — the US in March, Europe two weeks later — and the Southern Hemisphere moves in the opposite direction, so gaps stretch and shrink by 1–2 hours.

What is the time zone difference between New York and London?

5 hours most of the year (noon in New York = 5 pm in London). It briefly drops to 4 hours for about two weeks each March, because the US starts DST before the UK.

How many time zones are there in the world?

38 distinct UTC offsets are in active use, from UTC-12 to UTC+14, including half-hour offsets like India's UTC+5:30 and Nepal's UTC+5:45. The IANA database tracks over 400 named zones.

Is a time zone converter the same as a time zone calculator?

Yes in practice: both compute the difference between zones and translate a given time. "Calculator" usually emphasizes the difference in hours; "converter" emphasizes translating a specific time.

How do I calculate time zone difference manually?

Write each city's UTC offset with sign, then subtract: Sydney (+10) minus Los Angeles (−7) = 17 hours. If the result pushes past midnight, the date changes too.

Should I use EST or EDT for New York?

EST (UTC-5) applies November–March; EDT (UTC-4) applies March–November. If you don't want to think about it, write "New York time" or use America/New_York — tools resolve it correctly for any date.

What is the difference between GMT and UTC?

UTC is the modern global time standard used for precise timekeeping and computer systems. GMT is a historic civil time reference based on Greenwich; in everyday scheduling it is often treated as UTC+0, but UTC is the more precise standard.

How do I compare 3 or more time zones at once?

Use a world clock view instead of pairwise math: put all cities in one row, slide to a candidate hour, and check every city stays inside working hours. Our world clock does exactly this.