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There are 38 UTC offsets in use around the world, not 24. The reason: half-hour and quarter-hour time zones exist in India, Iran, Nepal, parts of Australia, and several island nations.
This is the full reference. Every time zone abbreviation, every UTC offset, the major cities in each zone, and whether they observe daylight saving time. Bookmark it.
Convert between any international time zones instantly.
Open Timezone ConverterThe Earth rotates 360 degrees in 24 hours. That is 15 degrees per hour. In theory, you could divide the globe into 24 equal slices, each 15 degrees of longitude wide, and each slice would be one hour apart. That is roughly what happens, but politics, geography, and history turned those neat slices into the messy map we have today.
Every time zone is defined as an offset from UTC (Coordinated Universal Time), which is the time at the Prime Meridian in Greenwich, England. UTC+0 is Greenwich. UTC-5 is 5 hours behind Greenwich (Eastern US). UTC+9 is 9 hours ahead (Japan).
Some facts that surprise people:
| UTC offset | Abbreviation | Name | Major locations |
|---|---|---|---|
| UTC-12 | AoE | Anywhere on Earth | Baker Island, Howland Island (uninhabited) |
| UTC-11 | SST | Samoa Standard | American Samoa, Midway Island |
| UTC-10 | HST | Hawaii Standard | Hawaii, Cook Islands (no DST) |
| UTC-9:30 | MART | Marquesas | Marquesas Islands (French Polynesia) |
| UTC-9 | AKST | Alaska Standard | Alaska (observes DST: AKDT = UTC-8) |
| UTC-8 | PST | Pacific Standard | LA, San Francisco, Seattle, Vancouver (DST: PDT = UTC-7) |
| UTC-7 | MST | Mountain Standard | Denver, Phoenix (AZ: no DST), Salt Lake City (DST: MDT = UTC-6) |
| UTC-6 | CST | Central Standard | Chicago, Houston, Dallas, Mexico City (DST: CDT = UTC-5) |
| UTC-5 | EST | Eastern Standard | New York, Miami, Toronto, Bogota (DST: EDT = UTC-4) |
| UTC-4 | AST | Atlantic Standard | Puerto Rico, Halifax, Caracas, Santiago (some observe DST) |
| UTC-3:30 | NST | Newfoundland Standard | St. John's, Newfoundland (DST: NDT = UTC-2:30) |
| UTC-3 | BRT | Brasilia Time | Sao Paulo, Buenos Aires, Montevideo |
| UTC-2 | GST | South Georgia | South Georgia Islands, mid-Atlantic |
| UTC-1 | CVT | Cape Verde Time | Cape Verde, Azores (during standard time) |
| UTC offset | Abbreviation | Name | Major locations |
|---|---|---|---|
| UTC+0 | GMT / UTC | Greenwich Mean / Coordinated Universal | London (winter), Dublin, Lisbon, Accra, Reykjavik |
| UTC+1 | CET | Central European | Paris, Berlin, Madrid, Rome, Amsterdam (DST: CEST = UTC+2) |
| UTC+2 | EET | Eastern European | Athens, Helsinki, Cairo, Johannesburg (DST: EEST = UTC+3) |
| UTC+3 | MSK | Moscow Time | Moscow, Istanbul, Riyadh, Nairobi (no DST) |
| UTC+3:30 | IRST | Iran Standard | Tehran (DST: IRDT = UTC+4:30) |
| UTC+4 | GST | Gulf Standard | Dubai, Abu Dhabi, Muscat, Baku (no DST) |
| UTC+4:30 | AFT | Afghanistan | Kabul (no DST) |
| UTC+5 | PKT | Pakistan Standard | Karachi, Islamabad, Tashkent (no DST) |
| UTC+5:30 | IST | India Standard | Mumbai, Delhi, Bangalore, Colombo (no DST) |
| UTC+5:45 | NPT | Nepal | Kathmandu (no DST) |
| UTC+6 | BST | Bangladesh Standard | Dhaka, Almaty (no DST) |
| UTC+6:30 | MMT | Myanmar | Yangon, Cocos Islands (no DST) |
| UTC+7 | ICT | Indochina | Bangkok, Jakarta, Ho Chi Minh City (no DST) |
| UTC+8 | CST / SGT / PHT | China / Singapore / Philippines | Beijing, Shanghai, Singapore, Manila, Perth (no DST) |
| UTC+8:45 | ACWST | Australian Central Western | Eucla, Western Australia border region |
| UTC+9 | JST / KST | Japan / Korea Standard | Tokyo, Seoul, Osaka (no DST) |
| UTC+9:30 | ACST | Australian Central | Adelaide, Darwin (SA observes DST, NT does not) |
| UTC+10 | AEST | Australian Eastern | Sydney, Melbourne, Brisbane (NSW/VIC observe DST, QLD does not) |
| UTC+10:30 | LHST | Lord Howe | Lord Howe Island (DST: +11) |
| UTC+11 | SBT | Solomon Islands | Solomon Islands, New Caledonia, Norfolk Island |
| UTC+12 | NZST | New Zealand Standard | Auckland, Wellington, Fiji (DST: NZDT = UTC+13) |
| UTC+12:45 | CHAST | Chatham Standard | Chatham Islands, New Zealand (DST: CHADT = UTC+13:45) |
| UTC+13 | TOT | Tonga | Tonga, Samoa, parts of Kiribati |
| UTC+14 | LINT | Line Islands | Kiribati's Line Islands (first place to enter each new day) |
The only country using a 45-minute offset. Nepal originally used UTC+5:30 (same as India) but switched to UTC+5:40 in 1920, then UTC+5:45 in 1986 to establish a distinct national identity from India. It also happens to roughly align with the solar time at the Gaurishankar peak.
A small archipelago 800km east of New Zealand. They use UTC+12:45 because they are far enough east of the main islands that standard NZST (UTC+12) would put them noticeably out of sync with solar noon. During DST, they jump to UTC+13:45.
China spans roughly the same longitude as the continental United States (about 60 degrees). The US uses 4 time zones. China uses 1. The government standardized on Beijing Time (UTC+8) in 1949 for national unity. This means sunrise in Kashgar (western China) does not happen until nearly 10 AM Beijing Time in winter. Many people in western China unofficially use UTC+6.
The International Date Line runs roughly along the 180th meridian in the Pacific Ocean, zigzagging around national borders. Cross it heading west and you skip a day. Cross it heading east and you repeat a day. Kiribati moved its portion of the Date Line in 1995 to put all its islands on the same calendar day, creating the UTC+13 and UTC+14 zones in the process.
About 70 countries observe DST. The rules vary widely:
| Region | DST starts | DST ends | Shift |
|---|---|---|---|
| US / Canada (most) | 2nd Sunday in March | 1st Sunday in November | +1 hour |
| EU / UK | Last Sunday in March | Last Sunday in October | +1 hour |
| Australia (SE states) | 1st Sunday in October | 1st Sunday in April | +1 hour |
| New Zealand | Last Sunday in September | 1st Sunday in April | +1 hour |
| Brazil | Abolished DST in 2019 | N/A | N/A |
| Most of Asia | No DST | N/A | N/A |
| Most of Africa | No DST | N/A | N/A |
The tricky part: the Northern and Southern Hemispheres observe DST at opposite times of year. When the US springs forward in March, Australia falls back. For 2-3 weeks in March and October, the time difference between the US and Australia changes by 1-2 hours compared to the rest of the year. This trips up people scheduling international calls during those transition weeks.
The military assigns a letter to each UTC offset. Zulu (Z) is UTC+0, which is why UTC is sometimes called "Zulu time." The letters go both directions from Z:
| Letter | UTC offset | NATO name |
|---|---|---|
| Z | UTC+0 | Zulu |
| A | UTC+1 | Alpha |
| B | UTC+2 | Bravo |
| M | UTC+12 | Mike |
| N | UTC-1 | November |
| R | UTC-5 (EST) | Romeo |
| S | UTC-6 (CST) | Sierra |
| T | UTC-7 (MST) | Tango |
| U | UTC-8 (PST) | Uniform |
| Y | UTC-12 | Yankee |
J (Juliet) is skipped because it represents the observer's local time. The letter I is not used for military timezone designations to avoid confusion with the numeral 1.
Some abbreviations map to multiple time zones. Watch out for these:
This is why developers and international businesses use UTC offsets (like UTC+5:30) or IANA timezone names (like America/New_York) instead of abbreviations. Abbreviations are fine for casual conversation within a region but cause confusion across borders.
Most of the world uses the 24-hour clock (sometimes called military time in the US). The US, Canada, Australia, and a few other English-speaking countries primarily use the 12-hour format with AM/PM. In international contexts, 24-hour format avoids ambiguity: 14:00 can only mean 2 PM, never 2 AM.
| 12-hour | 24-hour | 12-hour | 24-hour |
|---|---|---|---|
| 12:00 AM | 00:00 | 12:00 PM | 12:00 |
| 1:00 AM | 01:00 | 1:00 PM | 13:00 |
| 2:00 AM | 02:00 | 2:00 PM | 14:00 |
| 6:00 AM | 06:00 | 6:00 PM | 18:00 |
| 9:00 AM | 09:00 | 9:00 PM | 21:00 |
| 11:00 AM | 11:00 | 11:00 PM | 23:00 |
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