World Time Zones
Explore and understand every time zone across the globe. Search by city, region, or offset to find the exact time anywhere in the world.
Understanding Time Zones
A clear guide to UTC offsets, international standards, and seasonal adjustments.
How Time Zones Work
Earth rotates 360 degrees in 24 hours, meaning roughly 15 degrees of longitude equals one hour of solar difference. Standard time zones harmonize local clocks across nations.
UTC vs GMT Explained
GMT is an astronomical time zone anchored at the Royal Observatory in Greenwich. UTC is an atomic standard that provides high-precision time without seasonal changes.
Daylight Saving Time (DST)
Many countries advance clocks by one hour during spring to extend evening daylight. Our tool automatically calculates exact DST transitions for every global location.
Unusual UTC Offsets
Not every zone is offset by a full hour. Places like India (UTC+5:30), Nepal (UTC+5:45), and Newfoundland (UTC-3:30) operate on fractional offsets.
30 Major Time Zone Abbreviations
Reference table of standard codes, formal designations, UTC offsets, and example major cities.
| Code | Designation | Standard Offset | Representative Cities |
|---|---|---|---|
UTC | Coordinated Universal Time | UTC+0 | Reykjavik |
GMT | Greenwich Mean Time | UTC+0 | London |
CET | Central European Time | UTC+1 | Paris, Berlin, Rome |
CEST | Central European Summer Time | UTC+2 | Paris, Berlin |
EET | Eastern European Time | UTC+2 | Athens, Cairo, Helsinki |
EEST | Eastern European Summer Time | UTC+3 | Kyiv, Athens |
WET | Western European Time | UTC+0 | Lisbon |
BST | British Summer Time | UTC+1 | London |
MSK | Moscow Standard Time | UTC+3 | Moscow |
GST | Gulf Standard Time | UTC+4 | Dubai, Muscat |
PKT | Pakistan Standard Time | UTC+5 | Karachi, Islamabad |
IST | India Standard Time | UTC+5:30 | New Delhi, Mumbai |
NPT | Nepal Time | UTC+5:45 | Kathmandu |
BST | Bangladesh Standard Time | UTC+6 | Dhaka |
ICT | Indochina Time | UTC+7 | Bangkok, Hanoi, Jakarta |
CST | China Standard Time | UTC+8 | Beijing, Shanghai |
SGT | Singapore Time | UTC+8 | Singapore |
HKT | Hong Kong Time | UTC+8 | Hong Kong |
JST | Japan Standard Time | UTC+9 | Tokyo |
KST | Korea Standard Time | UTC+9 | Seoul |
ACST | Australian Central Standard Time | UTC+9:30 | Adelaide, Darwin |
AEST | Australian Eastern Standard Time | UTC+10 | Sydney, Melbourne, Brisbane |
NZST | New Zealand Standard Time | UTC+12 | Auckland, Wellington |
EST | Eastern Standard Time | UTC-5 | New York, Toronto, Miami |
EDT | Eastern Daylight Time | UTC-4 | New York, Washington D.C. |
CST | Central Standard Time (North America) | UTC-6 | Chicago, Dallas, Mexico City |
CDT | Central Daylight Time | UTC-5 | Chicago, Houston |
MST | Mountain Standard Time | UTC-7 | Denver, Phoenix |
PST | Pacific Standard Time | UTC-8 | Los Angeles, Vancouver, Seattle |
PDT | Pacific Daylight Time | UTC-7 | San Francisco, Los Angeles |
Frequently Asked Questions About Time Zones
Common technical and practical time zone questions answered.
GMT is a solar-based time zone historically tied to Greenwich, London. UTC is the modern atomic time standard used globally for aviation, satellites, and digital infrastructure.
Countries like India, Iran, Afghanistan, and Nepal chose fractional hour offsets to better align their local clocks with natural solar noon across their territory.
During DST, a region shifts forward by one hour (e.g. EST UTC-5 becomes EDT UTC-4). WorldTimeTool updates these offsets in real-time automatically.
The International Date Line roughly follows the 180° meridian in the Pacific Ocean. Crossing it westward moves the calendar forward one full day; crossing eastward moves back one day.
Your browser provides your system timezone directly via native web standards, allowing WorldTimeTool to instantly calculate your offset relative to any city on Earth.
Ready to Convert Between Time Zones?
Easily compare overlapping working hours across continents with our interactive timeline converter or track your team on our world clock.