Time terms and abbreviations

In international time management, many abbreviations are in use, which is a constant source of confusion. Here is an overview of the most important abbreviations.

image description — Overview

AM / PM

CET, MEZ,GMT, etc.: Time zone abbreviations

DCF77, MSF and others: The most important time signal transmitters

AM / PM

The abbreviations AM and PM can be found on watches with digital display in the 12-hour display as well as on flight plans and timetables of all kinds abroad. It is particularly widespread in the USA. There the "twelve-hour system" is usual, so in the afternoon one does not speak of 16 o'clock, but of 4 o'clock. AM and PM are used to distinguish between day and night. It is therefore said whether one speaks of morning/morning or afternoon/evening. But what does that mean?

The two abbreviations come from Latin: AM (Ante Meridiem): means "before noon", PM (Post Meridiem): means "after noon". There are different spellings, like e.g: AM and PM, a.m. and p.m., A.M. and P.M., A/M and P/M or AM / PM.

Especially in English speaking countries like Australia, New Zealand, Canada or the USA the 12-hour-count is used. In Great Britain, however, not, there as everywhere in Europe (and also in Germany) the 24-hour-counting (0:00 to 23:59 o'clock) is used (which is also called military time).

In the 24-hour count, 12:01 noon is followed by 12:01 noon and 13:00 on the hour. At night, there is the special feature in the 24-hour count that 00:00 follows 23:59 (in the 12-hour count, the change from AM to PM and vice versa takes place at 12:00, but the count continues from 12:00 to 12:59, then 1:00).

Not only with timetables, but also with appointments or dates of all kinds one must change in countries with 12-hour counting. A clock with a digital display is helpful, because you can easily change here. This is also possible with the smartphone, the Smartwatch or the tablet or laptop.

The 12-hour count goes back to the Middle Ages. The day was originally divided into two halves (light and dark or day and night), which was rather inaccurate.

With the invention of the clock, which appeared to the population mainly in the form of the tower clock at the churches, 12-hour counting was introduced. Because of the greater clarity, the 24-hour counting has become established in the administration as well as in the economy, which today is standard throughout Europe and many other parts of the world. In Germany, even the spelling of office and administrative hours is regulated in a DIN standard (5008).

On watches with digital display it is generally possible to switch between 12- and 24-hour display. Watches with analog display are typically in 12-hour mode, but there are also watches with 24-hour display (e.g. slow watches) or an extra hand for the 24-hour display on the outer ring of the dial.

CET, MEZ,GMT, etc.: Time zone abbreviations

This is an overview of all currently used time zones. Some can be found several times, e.g. for the CET zone (central european time) the abbreviation MEZ (mitteleuropäische Sommerzeit) is also used in German.

In addition to the time abbreviations listed in the list, there are a number of other time designations that can be stumbled upon, e.g.

TAI (Temps Atomique International), the international atomic time. Since it is based exclusively on an atomic time standard, it deviates increasingly from the usual time scales, which are based on solar time.

UT1 (Universal Time No.1) is such a solar time, which is determined by astronomical observation. Ultimately, it is based on the Earth's angle of rotation to the Sun, so unlike the TAI, it is not a uniform measure because it reflects changes in the Earth's rotation. There are other UT variants such as UT0, UT1D, UT1R and UT2, but all of them are usually only important for special scientific disciplines.

In the following overview, it should be noted that the same abbreviation is sometimes used for several time zones.
A country can also extend over several time zones.

Code	Time zone	UTC-Offset	DST	Countries
ACDT	Australian Central Daylight Time	+10:30	DST of ACST	1 country Australia
ACST	Australian Central Standard Time	+9:30	Standard time	1 country Australia
ACT	Acre Time	-5:00	Standard time	1 country Brazil
ACWST	Australian Central Western Standard Time	+8:45	Standard time	1 country Australia
ADT	Atlantic Daylight Time	-3:00	DST of AST	4 Countries Antigua and Barbuda Bermuda Canada Greenland
AEDT	Australian Eastern Daylight Time	+11:00	DST of AEST	1 country Australia
AEST	Australian Eastern Standard Time	+10:00	Standard time	1 country Australia
AFT	Afghanistan Time	+4:30	Standard time	1 country Afghanistan
AKDT	Alaska Daylight Time	-8:00	DST of AKST	1 country United States
AKST	Alaska Standard Time	-9:00	Standard time	1 country United States
ALMT	Eastern Kazakhstan Time	+6:00	Standard time	1 country Kazakhstan
AMST	Amazon Summertime	-3:00	DST of AMT	1 country Brazil
AMT	Amazon Time	-4:00	Standard time	1 country Brazil
AMT	Armenia Time	+4:00	Standard time	1 country Armenia
ANAT	Anadyr Time	+12:00	Standard time	1 country Russia
AQTT	Western Kazakhstan Time	+5:00	Standard time	1 country Kazakhstan
ART	Argentina Time	-3:00	Standard time	1 country Argentina
AST	Atlantic Standard Time	-4:00	Standard time	23 Countries Anguilla Antigua and Barbuda Aruba Barbados Bermuda Canada Curacao Dominica Dominican Republic Greenland Grenada Guadeloupe Martinique Montserrat Puerto Rico Saint Kitts and Nevis Saint Lucia Saint Martin Saint Vincent and the Grenadines Sint Maarten Trinidad and Tobago Turks and Caicos Islands United States
AST	Arabian Standard Time	+3:00	Standard time	5 Countries Bahrain Iraq Kuwait Qatar Yemen
AWST	Australian Western Standard Time	+8:00	Standard time	2 Countries Antarctica Australia
AZOST	Azores Summertime	+0:00	DST of AZOT	1 country Portugal
AZOT	Azores Time	-1:00	Standard time	1 country Portugal
AZT	Azerbaijan Time	+4:00	Standard time	1 country Azerbaijan
BDT	Bangladesh Standard Time	+6:00	Standard time	1 country Bangladesh
BNT	Brunei Time	+8:00	Standard time	1 country Brunei
BOT	Bolivia Time	-4:00	Standard time	1 country Bolivia
BRST	Brasilia Summertime	-2:00	DST of BRT	1 country Brazil
BRT	Brasilia Time	-3:00	Standard time	1 country Brazil
BST	British Summertime	+1:00	DST of GMT	5 Countries Guernsey Ireland Isle of Man Jersey United Kingdom
BST	Bougainville Standard Time	+11:00	Standard time	1 country Solomon Islands
BTT	Bhutan Time	+6:00	Standard time	1 country Bhutan
CAT	Central Africa Time	+2:00	Standard time	8 Countries Botswana Burundi Democratic Republic of the Congo Malawi Mozambique Rwanda Zambia Zimbabwe
CCT	Cocos Islands Time	+6:30	Standard time	1 country Cocos Islands
CDT	Cuba Daylight Time	-4:00	DST of CST	1 country Cuba
CDT	Central Daylight Time	-5:00	DST of CST	3 Countries Canada Mexico United States
CEST	Central European Summertime	+2:00	DST of CET	28 Countries Albania Andorra Austria Belgium Bosnia and Herzegovina Croatia Denmark France Germany Gibraltar Hungary Italy Liechtenstein Luxembourg Macedonia Malta Monaco Montenegro Netherlands Norway Poland San Marino Serbia Slovakia Slovenia Spain Sweden Switzerland
CET	Central European Time	+1:00	Standard time	30 Countries Albania Algeria Andorra Austria Belgium Bosnia and Herzegovina Croatia Denmark France Germany Gibraltar Hungary Italy Liechtenstein Luxembourg Macedonia Malta Monaco Montenegro Netherlands Norway Poland San Marino Serbia Slovakia Slovenia Spain Sweden Switzerland Tunisia
CHADT	Chatham Daylight Time	+13:45	DST of CHAST	1 country New Zealand
CHAST	Chatham Standard Time	+12:45	Standard time	1 country New Zealand
CHOST	Choibalsan Summertime	+9:00	DST of CHOT	1 country Mongolia
CHOT	Choibalsan Time	+8:00	Standard time	1 country Mongolia
CHUT	Chuuk Time	+10:00	Standard time	1 country Micronesia
CKT	Cook Island Time	-10:00	Standard time	1 country Cook Islands
CLT	Chile Standard Time	-3:00	Standard time	2 Countries Antarctica Chile
COT	Colombia Time	-5:00	Standard time	1 country Colombia
CST	Cuba Standard Time	-5:00	Standard time	1 country Cuba
CST	Central Standard Time	-6:00	Standard time	9 Countries Belize Canada Costa Rica El Salvador Guatemala Honduras Mexico Nicaragua United States
CST	China Standard Time	+8:00	Standard time	3 Countries China Macao Taiwan
CVT	Cape Verde Time	-1:00	Standard time	1 country Cape Verde
CXT	Christmas Island Time	+7:00	Standard time	1 country Christmas Island
CHST	Chamorro Standard Time	+10:00	Standard time	2 Countries Guam Northern Mariana Islands
DAVT	Davis Time	+7:00	Standard time	1 country Antarctica
DDUT	Dumont-d'Urville Time	+10:00	Standard time	1 country French Southern Territories
EAST	Easter Island Standard Time	-5:00	Standard time	1 country Chile
EAT	East Africa Time	+3:00	Standard time	12 Countries Comoros Djibouti Eritrea Ethiopia Kenya Madagascar Mayotte Somalia South Sudan Sudan Tanzania Uganda
ECT	Ecuador Time	-5:00	Standard time	1 country Ecuador
EDT	Eastern Daylight Time	-4:00	DST of EST	3 Countries Bahamas Canada United States
EEST	Eastern European Summertime	+3:00	DST of EET	14 Countries Aland Islands Bulgaria Cyprus Estonia Finland Greece Jordan Latvia Lebanon Lithuania Moldova Romania Syria Ukraine
EET	Eastern European Time	+2:00	Standard time	18 Countries Aland Islands Bulgaria Cyprus Egypt Estonia Finland Greece Jordan Latvia Lebanon Libya Lithuania Moldova Palestinian Territory Romania Russia Syria Ukraine
EGST	Eastern Greenland Summertime	+0:00	DST of EGT	1 country Greenland
EGT	East Greenland Time	-1:00	Standard time	1 country Greenland
EST	Eastern Standard Time	-5:00	Standard time	8 Countries Bahamas Canada Cayman Islands Haiti Jamaica Mexico Panama United States
FJST	Fiji Summertime	+13:00	DST of FJT	1 country Fiji
FJT	Fiji Time	+12:00	Standard time	1 country Fiji
FKST	Falkland Islands Standard Time	-3:00	Standard time	1 country Falkland Islands
GALT	Galapagos Time	-6:00	Standard time	1 country Ecuador
GAMT	Gambier Time	-9:00	Standard time	1 country French Polynesia
GET	Georgia Time	+4:00	Standard time	1 country Georgia
GFT	French Guiana Time	-3:00	Standard time	1 country French Guiana
GILT	Gilbert Island Time	+12:00	Standard time	1 country Kiribati
GMT	Greenwich Mean Time	+0:00	Standard time	21 Countries Burkina Faso Gambia Ghana Greenland Guernsey Guinea Guinea-Bissau Iceland Ireland Isle of Man Ivory Coast Jersey Liberia Mali Mauritania Saint Helena Sao Tome and Principe Senegal Sierra Leone Togo United Kingdom
GST	Georgia Standard Time	-2:00	Standard time	1 country South Georgia and the South Sandwich Islands
GST	Gulf Standard Time	+4:00	Standard time	2 Countries Oman United Arab Emirates
GYT	Guyana Time	-4:00	Standard time	1 country Guyana
HDT	Hawaii-Aleutian Daylight Time	-9:00	DST of	1 country United States
HKT	Hong Kong Time	+8:00	Standard time	1 country Hong Kong
HOVST	Hovd Summertime	+8:00	DST of HOVT	1 country Mongolia
HOVT	Hovd Time	+7:00	Standard time	1 country Mongolia
HST	Hawaii Standard Time	-10:00	Standard time	1 country United States
ICT	Indochina Time	+7:00	Standard time	4 Countries Cambodia Laos Thailand Vietnam
IDT	Israel Daylight Time	+3:00	DST of IST	1 country Israel
IOT	Indian Chagos Time	+6:00	Standard time	1 country British Indian Ocean Territory
IRDT	Iran Daylight Time	+4:30	DST of IRST	1 country Iran
IRKT	Irkutsk Time	+8:00	Standard time	1 country Russia
IRST	Iran Standard Time	+3:30	Standard time	1 country Iran
IST	Irish Summertime	+1:00	DST of IST	1 country Ireland
IST	Israel Standard Time	+2:00	Standard time	1 country Israel
IST	India Standard Time	+5:30	Standard time	2 Countries India Sri Lanka
JST	Japan Standard Time	+9:00	Standard time	1 country Japan
KGT	Kyrgyzstan Time	+6:00	Standard time	1 country Kyrgyzstan
KOST	Kosrae Time	+11:00	Standard time	1 country Micronesia
KRAT	Krasnoyarsk Time	+7:00	Standard time	1 country Russia
KST	Korea Standard Time	+9:00	Standard time	1 country South Korea
LHDT	Lord Howe Daylight Time	+11:30	DST of LHST	1 country Australia
LHST	Lord Howe Standard Time	+10:30	Standard time	1 country Australia
LINT	Line Islands Time	+14:00	Standard time	1 country Kiribati
MART	Marquesas Time	-9:30	Standard time	1 country French Polynesia
MAWT	Mawson Time	+5:00	Standard time	1 country Antarctica
MDT	Mountain Daylight Time	-6:00	DST of MST	3 Countries Canada Mexico United States
MESZ	Mitteleuropäische Sommerzeit	+2:00	DST of MEZ	28 Countries Albania Andorra Austria Belgium Bosnia and Herzegovina Croatia Denmark France Germany Gibraltar Hungary Italy Liechtenstein Luxembourg Macedonia Malta Monaco Montenegro Netherlands Norway Poland San Marino Serbia Slovakia Slovenia Spain Sweden Switzerland
MEZ	Mitteleuropäische Zeit	+1:00	Standard time	30 Countries Albania Algeria Andorra Austria Belgium Bosnia and Herzegovina Croatia Denmark France Germany Gibraltar Hungary Italy Liechtenstein Luxembourg Macedonia Malta Monaco Montenegro Netherlands Norway Poland San Marino Serbia Slovakia Slovenia Spain Sweden Switzerland Tunisia
MHT	Marshall Islands Time	+12:00	Standard time	1 country Marshall Islands
MIST	Macquarie Island Station Time	+11:00	Standard time	1 country Australia
MMT	Myanmar Time	+6:30	Standard time	1 country Myanmar
MSK	Moscow Standard Time	+3:00	Standard time	3 Countries Belarus Russia Ukraine
MST	Mountain Standard Time	-7:00	Standard time	3 Countries Canada Mexico United States
MUT	Mauritius Time	+4:00	Standard time	1 country Mauritius
MVT	Maldives Time	+5:00	Standard time	1 country Maldives
MYT	Malaysia Time	+8:00	Standard time	1 country Malaysia
NCT	New Caledonia Time	+11:00	Standard time	1 country New Caledonia
NDT	Newfoundland Daylight Time	-2:30	DST of NST	1 country Canada
NFT	Norfolk Time	+11:00	Standard time	1 country Norfolk Island
NOVT	Novosibirsk Time	+6:00	Standard time	1 country Russia
NPT	Nepal Time	+5:45	Standard time	1 country Nepal
NRT	Nauru Time	+12:00	Standard time	1 country Nauru
NST	Newfoundland Standard Time	-3:30	Standard time	1 country Canada
NUT	Niue Time	-11:00	Standard time	1 country Niue
NZDT	New Zealand Daylight Time	+13:00	DST of NZST	2 Countries Antarctica New Zealand
NZST	New Zealand Standard Time	+12:00	Standard time	2 Countries Antarctica New Zealand
OESZ	Osteuropäische Sommerzeit	+3:00	DST of OEZ	14 Countries Aland Islands Bulgaria Cyprus Estonia Finland Greece Jordan Latvia Lebanon Lithuania Moldova Romania Syria Ukraine
OEZ	Osteuropäische Zeit	+2:00	Standard time	18 Countries Aland Islands Bulgaria Cyprus Egypt Estonia Finland Greece Jordan Latvia Lebanon Libya Lithuania Moldova Palestinian Territory Romania Russia Syria Ukraine
OMST	Omsk Standard Time	+6:00	Standard time	1 country Russia
ORAT	Western Kazakhstan Time	+5:00	Standard time	1 country Kazakhstan
PDT	Pacific Daylight Time	-7:00	DST of PST	3 Countries Canada Mexico United States
PET	Peru Time	-5:00	Standard time	1 country Peru
PETT	Kamchatka Time	+12:00	Standard time	1 country Russia
PGT	Papua New Guinea Time	+10:00	Standard time	1 country Papua New Guinea
PHOT	Phoenix Island Time	+13:00	Standard time	1 country Kiribati
PHT	Philippines Time	+8:00	Standard time	1 country Philippines
PKT	Pakistan Standard Time	+5:00	Standard time	1 country Pakistan
PMDT	Pierre & Miquelon Daylight Time	-2:00	DST of PMST	1 country Saint Pierre and Miquelon
PMST	Pierre & Miquelon Standard Time	-3:00	Standard time	1 country Saint Pierre and Miquelon
PONT	Pohnpei Standard Time	+11:00	Standard time	1 country Micronesia
PST	Pitcairn Standard Time	-8:00	Standard time	4 Countries Canada Mexico Pitcairn United States
PWT	Palau Time	+9:00	Standard time	1 country Palau
PYST	Paraguay Summertime	-3:00	DST of PYT	1 country Paraguay
PYT	Paraguay Time	-4:00	Standard time	1 country Paraguay
PYT	Pyongyang Time	+8:30	Standard time	1 country North Korea
QYZT	Eastern Kazakhstan Time	+6:00	Standard time	1 country Kazakhstan
RET	Réunion Time	+4:00	Standard time	1 country Reunion
ROTT	Rothera Time	-3:00	Standard time	1 country Antarctica
SAKT	Sakhalin Time	+10:00	Standard time	1 country Russia
SAMT	Samara Time	+4:00	Standard time	1 country Russia
SAST	South Africa Standard Time	+2:00	Standard time	3 Countries Lesotho South Africa Swaziland
SBT	Solomon Islands Time	+11:00	Standard time	1 country Solomon Islands
SCT	Seychelles Time	+4:00	Standard time	1 country Seychelles
SGT	Singapore Time	+8:00	Standard time	1 country Singapore
SRET	Srednekolymsk Time	+11:00	Standard time	1 country Russia
SRT	Suriname Time	-3:00	Standard time	1 country Suriname
SST	Samoa Standard Time	-11:00	Standard time	2 Countries American Samoa Samoa
SYOT	Syowa Time	+3:00	Standard time	1 country Antarctica
TAHT	Tahiti Time	-10:00	Standard time	1 country French Polynesia
TFT	French Southern and Antarctic Time	+5:00	Standard time	1 country French Southern Territories
TJT	Tajikistan Time	+5:00	Standard time	1 country Tajikistan
TKT	Tokelau Time	+13:00	Standard time	1 country Tokelau
TLT	East Timor Time	+9:00	Standard time	1 country East Timor
TMT	Turkmenistan Time	+5:00	Standard time	1 country Turkmenistan
TOT	Tonga Time	+13:00	Standard time	1 country Tonga
TRT	Turkey Time	+3:00	Standard time	1 country Turkey
TVT	Tuvalu Time	+12:00	Standard time	1 country Tuvalu
ULAST	Ulaanbaatar Summertime	+9:00	DST of ULAT	1 country Mongolia
ULAT	Ulaanbaatar Time	+8:00	Standard time	1 country Mongolia
UTC	Universal Time Coordinated	0:00	Standard time	1 country
UYT	Uruguay Time	-3:00	Standard time	1 country Uruguay
UZT	Uzbekistan Time	+5:00	Standard time	1 country Uzbekistan
VET	Venezuelan Standard Time	-4:30	Standard time	1 country Venezuela
VLAT	Vladivostok Time	+10:00	Standard time	1 country Russia
VOST	Vostok Time	+6:00	Standard time	1 country Antarctica
VUT	Vanuatu Time	+11:00	Standard time	1 country Vanuatu
WAST	West Africa Summertime	+2:00	DST of WAT	1 country Namibia
WAT	West Africa Time	+1:00	Standard time	12 Countries Angola Benin Cameroon Central African Republic Chad Democratic Republic of the Congo Equatorial Guinea Gabon Namibia Niger Nigeria Republic of the Congo
WEST	Western European Summertime	+1:00	DST of WET	5 Countries Faroe Islands Morocco Portugal Spain Western Sahara
WET	Western European Time	+0:00	Standard time	5 Countries Faroe Islands Morocco Portugal Spain Western Sahara
WESZ	Western European Summertime	+1:00	DST of WEZ	5 Countries Faroe Islands Morocco Portugal Spain Western Sahara
WEZ	Westeuropäische Zeit	+0:00	Standard time	5 Countries Faroe Islands Morocco Portugal Spain Western Sahara
WFT	Wallis and Futuna Time	+12:00	Standard time	1 country Wallis and Futuna
WGST	Western Greenland Summertime	-2:00	DST of WGT	1 country Greenland
WGT	West Greenland Time	-3:00	Standard time	1 country Greenland
WIB	Western Indonesian Time	+7:00	Standard time	1 country Indonesia
WIT	Eastern Indonesian Time	+9:00	Standard time	1 country Indonesia
WITA	Central Indonesian Time	+8:00	Standard time	1 country Indonesia
WSDT	West Samoa Daylight Time	+14:00	DST of WSST	1 country Samoa
WSST	West Samoa Standard Time	+13:00	Standard time	1 country Samoa
YAKT	Yakutsk Time	+9:00	Standard time	1 country Russia
YEKT	Yekaterinburg Time	+5:00	Standard time	1 country Russia

DCF77, MSF and others: The most important time signal transmitters

In order to transmit the exact time of an atomic clock, e.g. to radio clocks (radio wristwatches, radio wall clocks or radio alarm clocks), but also to radio and TV stations, there are a wide variety of time signal transmitters worldwide.
Here is an overview of the most important transmitters.

Abbreviation	Location
DCF77	Mainflingen/ Germany
MSF	Anthorn / UK
JJY	Japan
WWV	Fort Collins, CO / USA
WWVH	Hawaii / USA
BPC	Singapore / China

You can find more information on time signal transmitters here

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Time terms and abbreviations

Overview

AM / PM

CET, MEZ,GMT, etc.: Time zone abbreviations

DCF77, MSF and others: The most important time signal transmitters

Top radiocontrolled watches

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