Difference Wiki

EDT vs. GMT: What's the Difference?

Edited by Harlon Moss || By Janet White || Published on January 20, 2024
EDT (Eastern Daylight Time) is a time zone observed in parts of North America, offset by -4 hours from GMT (Greenwich Mean Time), a standard time against which others are set.

Key Differences

EDT, standing for Eastern Daylight Time, is the time zone observed during daylight saving time in the Eastern part of North America. GMT, or Greenwich Mean Time, is a time standard that originally referred to mean solar time at the Royal Observatory in Greenwich, London.
EDT is used during the warmer months (spring to fall) and is 4 hours behind GMT. GMT is not subject to seasonal changes and remains constant throughout the year, serving as a reference time worldwide.
Regions observing EDT switch to Eastern Standard Time (EST), which is 5 hours behind GMT, during the colder months when daylight saving time is not in effect. GMT, in contrast, does not change and has no daylight saving variation.
EDT aligns with areas like New York City and Toronto, affecting local activities and business hours. GMT is a global time standard, used as the basis for time zones worldwide and important for international coordination.
For global communication and travel, understanding the difference between EDT and GMT is crucial, especially for those dealing with regions observing daylight saving time. GMT serves as a fixed point of reference for calculating time differences globally.

Comparison Chart

Time Zone Offset

UTC -4 hours during daylight saving time
UTC +0 hours, no daylight saving adjustment


Eastern parts of North America
Global standard time

Daylight Saving Time

Observed, shifts from EST
Not observed, remains constant

Representative Location

New York City, Toronto
Greenwich, London

Role in Global Coordination

Regional time zone, changes seasonally
Fixed reference for world time zones

EDT and GMT Definitions


Four hours behind GMT.
When it's noon GMT, it's 8 AM EDT.


A time standard used globally.
GMT is used as a reference time worldwide.


Time zone used in Eastern North America during daylight saving time.
The meeting is scheduled for 10 AM EDT.


Basis for time zones worldwide.
Local times are often expressed as offsets from GMT.


Affects local business hours in its region.
The store opens at 9 AM EDT.


Not subject to daylight saving time.
GMT remains constant throughout the year.


Important for timing in areas like New York.
The New York stock exchange operates on EDT.


Integral for international time coordination.
Flight schedules are often coordinated using GMT.


Switches to EST in winter.
In November, we'll change from EDT to EST.


Originally based on solar time at Greenwich.
GMT was established at the Royal Observatory in Greenwich.


The local time at the 0 meridian passing through Greenwich, England; it is the same everywhere


Is GMT affected by seasons?

No, it's the same all year round.

When is EDT used?

During daylight saving time in parts of North America.

What does EDT stand for?

Eastern Daylight Time.

What happens to EDT in winter?

It changes to Eastern Standard Time (EST).

Which major cities use EDT?

Cities like New York and Toronto.

What is GMT?

Greenwich Mean Time, a global time standard.

How far is EDT behind GMT?

4 hours during daylight saving time.

When does EDT start each year?

Typically in March.

Does GMT observe daylight saving?

No, it does not.

Does EDT affect the whole of North America?

Only the Eastern part.

Can GMT be used as a local time zone?

It can be, particularly near the Greenwich meridian.

What's the role of GMT in aviation?

It's used for flight schedules and air traffic control.

How does daylight saving time affect EDT?

EDT is the daylight saving time observation for the Eastern Time Zone.

Is GMT used for international events?

Yes, it's often used for global coordination.

What's the difference between GMT and UTC?

They're functionally the same; UTC is more precise.

Why is GMT important?

It's a reference point for time zones worldwide.

Who uses GMT?

It's used internationally for various purposes.

Does EDT apply to all of the Eastern US?

Most, but not all areas.

How is GMT determined?

Originally, it was based on mean solar time at Greenwich.

Are EDT and GMT always 4 hours apart?

Only during North America's daylight saving time.
About Author
Written by
Janet White
Janet White has been an esteemed writer and blogger for Difference Wiki. Holding a Master's degree in Science and Medical Journalism from the prestigious Boston University, she has consistently demonstrated her expertise and passion for her field. When she's not immersed in her work, Janet relishes her time exercising, delving into a good book, and cherishing moments with friends and family.
Edited by
Harlon Moss
Harlon is a seasoned quality moderator and accomplished content writer for Difference Wiki. An alumnus of the prestigious University of California, he earned his degree in Computer Science. Leveraging his academic background, Harlon brings a meticulous and informed perspective to his work, ensuring content accuracy and excellence.

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