HAST = Hawaii Aleutian Standard Time (used by both) = UTC-10:00.HST = Hawaii Standard Time (used by Hawaii only) = UTC-10:00.Would you change your local customs for a small group of people thousands of miles away? Probably not. Additionally, the Aleutian Islands use daylight saving time in the summer, and Hawaii does not. So why not just use HAST? Well, 'Aleutian' refers to the Aleutian Islands of Alaska, a location 2,423 miles away, and with a population of under 10,000 (as compared with about 1.4 million people living in Hawaii). So there are two different time zone abbreviations used for Hawaii, that mean the exact same thing. But the US legally defines it as 'Hawaii-Aleutian Standard Time' (HAST). Most Hawaiians would say that their time zone is 'Hawaii Standard Time' (HST).

It would seem that on a global scale, we cannot agree on the naming conventions for our time zones!īut surely in a single location, one that doesn't follow daylight saving time, we can have a single abbreviation there? Certainly not! Both Ireland and England use the term 'Greenwich Mean Time' (GMT) during the winter, but in the summer, England switches to 'British Summer Time' (BST) and Ireland switches to 'Irish Standard Time' (IST). That last one is quite interesting, because Irish Standard Time is actually a daylight saving time zone. Central Summer Time (Australia) = UTC+10:30.Central Standard Time (Australia) = UTC+09:30.Central Standard Time (North America) = UTC-06:00.You can not parse a string containing a time zone abbreviation and be absolutely certain that it was interpreted correctly. But computers do not have such intuition. Humans are usually intelligent enough to apply other contextual clues such as the country and time of year. If you're formatting a string of text to show a user a date and time, sure - you can append a time zone abbreviation. Therefore, time zone abbreviations are not unique identifiers! Do not attempt to use them as such. So now we see that on a global scale, the simple abbreviation EST could refer to any of three different possible time zone offsets. So for this reason, in contexts where it's important to distinguish, some times EDT is used anyway, or you may even see AEDT. However, that now means EST could refer to 'Eastern Summer Time' as well. But who's to say that the leading A shouldn't stand for America? Forcing another culture to change their naming conventions to make room for someone else is just plain egocentric.Īdditionally, the Australians (like the British) don't use the term 'daylight time', they instead call it 'summer time', which is appropriate since daylight time always occurs in the summer. If you don't live in Australia, you might be tempted to use the abbreviation AEST, and many have done just that. You see, America is not the only place with an eastern coastline, and the Australians have also called their eastern time zone 'Eastern Standard Time'. Then we're ok - right? Well, not exactly. Ok, so let's standardize just on the English names. The other North American time zones have French names too. While an English-speaking Canadian citizen might say 'Eastern Standard Time' or 'Eastern Daylight Time', a French-speaking Canadian citizen would say 'heure normale de l’Est' or 'heure avancée de l’Est' - abbreviated by HNE or HAE. The story doesn't end here.Įastern Time is also used by Canada, and Canada has two official languages - English and French. ET = Eastern Time = īut don't think it's that simple.EDT = Eastern Daylight Time = UTC-04:00.EST = Eastern Standard Time = UTC-05:00.If you want to refer to the entire Eastern Time zone, without regard to whether daylight saving time is in effect or not, the correct abbreviation would be ET. If you continue to use the term EST - you're doing it wrong! During this period, the name for the time zone changes to 'Eastern Daylight Time', abbreviated by EDT. However, during a significant portion of the year, most places in the United States follow daylight saving time. If you live in the United States, you might recognize it as 'Eastern Standard Time', which is a time zone used in places like New York City, Washington D.C., and Miami.

What does the abbreviation EST mean? I'm sure you've seen that before.

East coast time zone gmt