Time Zone Converter
Convert a time across all major world time zones instantly.
How time zones work
Time zones divide the Earth into regions that observe the same local time. The planet rotates 360° every 24 hours, which means it moves 15° of longitude per hour. The world is therefore divided into 24 primary time zones, each nominally 15° wide — though political boundaries cause many zones to deviate from this neat geometry.
All time zones are defined as offsets from UTC (Coordinated Universal Time) — the modern successor to GMT. A time zone labeled UTC+3 means local clocks are set 3 hours ahead of UTC. UTC−5 means clocks are 5 hours behind. Converting between any two zones is a matter of adding or subtracting their UTC offsets.
Local time in zone B = Local time in zone A − Offset(A) + Offset(B)UTC vs. GMT: what is the difference?
GMT (Greenwich Mean Time) is a historical time standard based on the solar time at the Royal Observatory in Greenwich, London. UTC is a modern atomic-clock-based standard that replaced GMT for scientific and technical purposes. For everyday time zone conversions, they are functionally identical — both sit at offset 0.
The key distinction: GMT can technically vary slightly with Earth's rotation, while UTC is maintained by atomic clocks and stays within 0.9 seconds of solar time through the addition of occasional "leap seconds." Aviation, internet infrastructure, and global finance all use UTC as the universal reference.
Daylight saving time (DST): the complication
Many countries shift their clocks forward by one hour in summer and back in winter — a practice called Daylight Saving Time (DST) or Summer Time. This means a country's UTC offset changes twice a year, and not all countries shift on the same date.
| Zone | Standard time | Summer (DST) | DST period (approx.) |
|---|---|---|---|
| New York (ET) | UTC−5 | UTC−4 | Mar → Nov |
| Los Angeles (PT) | UTC−8 | UTC−7 | Mar → Nov |
| London (GMT/BST) | UTC+0 | UTC+1 | Mar → Oct |
| Amsterdam (CET) | UTC+1 | UTC+2 | Mar → Oct |
| Sydney (AEST) | UTC+10 | UTC+11 | Oct → Apr |
| Tokyo (JST) | UTC+9 | No DST | — |
| Dubai (GST) | UTC+4 | No DST | — |
| India (IST) | UTC+5:30 | No DST | — |
This converter uses fixed UTC offsets and does not automatically apply DST adjustments. Always verify the current local offset for any zone where DST applies, especially when scheduling international meetings in spring or autumn.
Unusual time zones
Most time zones are whole-hour offsets, but several countries use half-hour or even quarter-hour offsets:
India (IST): UTC+5:30 (half-hour offset)
Nepal (NPT): UTC+5:45 (quarter-hour offset)
Iran (IRST): UTC+3:30
Australia/Adelaide: UTC+9:30
Lord Howe Island: UTC+10:30 (and UTC+11 in summer)China spans five geographic time zones but uses a single national time (UTC+8) across the entire country — meaning sunrise in Kashgar, Xinjiang can occur as late as 10 AM local time. This is a political rather than geographic decision.
Common real-world uses
Tips for scheduling across time zones
- Always anchor to UTC when communicating times. Writing "14:00 UTC" removes all ambiguity. Saying "2 PM" without a zone is meaningless in an international context and a common cause of missed meetings.
- Watch out for date changes. A meeting at 10 PM in New York (UTC−5) is 3 AM the next day in Amsterdam (UTC+1). When a conversion crosses midnight, the day itself changes — calendar invites must reflect the correct date for each recipient's time zone.
- DST transitions cause temporary confusion. When the US shifts clocks in March but Europe has not yet shifted (it shifts a few weeks later), the transatlantic time difference temporarily changes by one hour. During this period, a meeting scheduled as "9 AM ET" in a calendar without DST awareness will appear at the wrong time for European participants.
- ISO 8601 is the international date-time standard. Writing timestamps as "2025-06-15T14:00:00Z" (the Z denotes UTC) is unambiguous regardless of locale. This format is used in APIs, logs, and international documents to eliminate date and time misunderstandings.
Frequently asked questions
How do time zone conversions work?
Each zone is defined as an offset from UTC. To convert, find the difference between the two zones' offsets and add or subtract it from the original time.
What is UTC?
Coordinated Universal Time (UTC) is the global time standard from which all time zones are offset. It does not change for daylight saving.
Does this account for daylight saving time?
Yes. The conversion reflects the current daylight saving rules for each zone so the result matches local clocks.
Why is scheduling across time zones confusing?
Different regions start and end daylight saving on different dates, and some do not observe it at all, so the offset between two cities can change during the year.
All times convert through UTC. Daylight saving time not automatically accounted for — check local DST status.