Difference between EST and EDT

By: | Updated: May-16, 2021

The terms EST and EDT are often used interchangeably, which causes confusion. There are times when both terms are used in the same sentence to describe the same time zone.

These terms are used in different parts of the world, and there is a significant difference between them. The problem is that many people are not aware of the difference between EST and EDT. Therefore, this article attempts to provide the answer to the question; what is the difference between EST and EDT?

Summary Table

EST EDT
EST stands for Eastern Standard Time EDT stands for Eastern Daylight Time
It is used in the eastern part of the United States, Canada, Caribbean, and Central America It is used in the eastern part of Canada and in most parts of Europe
The time zone of EST is five hours behind Greenwich Mean Time (GMT) The time zone of EDT is four hours behind Greenwich Mean Time (GMT)

Definitions

EST vs EDT

EST stands for Eastern Standard Time. It is used in the eastern part of the United States, Canada, Caribbean, and Central America. In these regions, EST is a time zone that is five hours behind Greenwich Mean Time (GMT). The standard time of the United States and Canada falls within the Eastern Time Zone.

In most of these regions, daylight saving time (DST) takes place during summer months. During this period, the clock advances by one hour and EST becomes EDT (Eastern Daylight Time).

In some countries in Europe, EST is known as EET (Eastern European Time). This name is used to describe the time difference between Greenwich Mean Time and Eastern European Summer Time. Therefore, EET can be said to be one hour ahead of GMT during summer months. During winter months when there is no DST in Europe, EET becomes CET (Central European Time), which means that it has a two-hour difference with GMT. In some places where CET is used, it can also be called CEST (Central European Summer Time). When it is 12 noon in EST, it is 7 pm in London.

EST vs EDT

To put it simply, the main differences between EST and EDT can be divided into:

  1. Time Zones: The time zones of EST and EDT are different. The time zone of EST is used in the eastern part of the United States, Canada, Caribbean, and Central America. On the other hand, EDT is used in the eastern part of Canada and in most parts of Europe. As mentioned above, in these regions, the difference between EST and EDT is five hours. However, during summer months when DST is in effect, this difference reduces to four hours.
  2. Local Mean Time: The local mean time refers to the mean solar time or clock time on a 24-hour scale that follows a uniform rate over a period of one day. When we consider local mean time as compared to standard time or daylight saving time (DST), it can be said that it does not vary with respect to DST changes unlike standard time or daylight saving time which vary with respect to DST changes. Local mean time is the same in both winter and summer. In other words, the local mean time does not change throughout the year.
  3. Standard Time: The term standard time refers to a uniform system of clock time used by a particular region during a specific period of the year. The standard time is the same throughout the region and is based on solar time. It is different from daylight saving time (DST) which is based on seasonal changes in solar time.
  4. Daylight Saving Time: Daylight saving or daylight savings refers to advancing clocks during summer months so that there will be more daylight hours in a day. Therefore, clocks are advanced by one hour so that people can utilize the extra daylight hours for activities such as outdoor work or recreation.

When is EST and EDT observed?

Most of the United States and Canada observe EST from November to March. However, the only exceptions are for some places in the US state of Indiana and parts of the Canadian province of Saskatchewan. In these places, DST is observed from March to November.

In Europe, summer time is observed from March to October. In some countries, summer time is observed from the end of March to the end of October. In the United States and Canada, EDT is observed from April to October. It starts at 2 am and ends at 3 am in these regions.

Is the East Coast on EST or EDT?

Most of the eastern part of the United States observes EST. However, some states on the East Coast observe EDT. These states include Delaware, Indiana, Kentucky, Maine, Massachusetts, New Hampshire, New Jersey, North Carolina, Ohio, Pennsylvania and Virginia. The reason for this is that these states lie within the Eastern Time Zone and not in the Central Time Zone. Therefore, these states do not observe DST during summer months.

Why do some countries observe DST and others do not?

Many countries observe DST. However, there are also a few countries that do not observe it. The reason for this is that it is not mandatory for a country to observe DST. Countries that observe DST are those that lie within the same time zone. Therefore, in order to have a uniform time across the country, these countries change their clocks during summer months.

Countries that do not observe DST include China, Japan and North Korea. The reason for this is that they are located far away from the equator and have different climatic conditions than other countries in their region. In addition to this, these countries do not share any borders with other countries in their region.

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