GMT vs. BST: Know the Difference
By Shumaila Saeed || Published on January 3, 2024
GMT (Greenwich Mean Time) is the time zone at the Prime Meridian, used year-round; BST (British Summer Time) is GMT+1, used in the UK during daylight saving time.
Key Differences
Greenwich Mean Time (GMT) is the mean solar time at the Royal Observatory in Greenwich, London, and is considered the standard time against which all other time zones are set. British Summer Time (BST) is the daylight saving time observed in the UK, where clocks are advanced by one hour from GMT during the summer months.
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Jan 03, 2024
GMT remains constant throughout the year, serving as a reference point for coordinating international time. BST, on the other hand, is a seasonal adjustment, typically beginning on the last Sunday in March and ending on the last Sunday in October, effectively moving an hour of daylight from morning to evening.
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Jan 03, 2024
GMT is often used as a global time standard, crucial for international communications, aviation, and the internet. In contrast, BST is a local time adjustment specific to the UK and affects daily schedules, broadcasting timings, and business operations during its period of application.
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Jan 03, 2024
In GMT, there is no alteration for daylight saving, reflecting the solar time at the Prime Meridian. BST, however, is designed to make better use of natural daylight during the longer days of summer in the UK.
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Jan 03, 2024
While GMT is a time zone without any daylight saving adjustments, BST effectively shifts the time zone to GMT+1, aligning the UK's daytime hours more closely with daylight during the summer months.
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Jan 03, 2024
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Comparison Chart
Definition
Mean solar time at the Prime Meridian in Greenwich, London.
Daylight saving time in the UK, one hour ahead of GMT.
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Jan 03, 2024
Daylight Saving Adjustment
No adjustment for daylight saving.
Adjusted forward by one hour during summer months.
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Jan 03, 2024
Period of Use
Used year-round.
Used typically between the last Sunday in March and the last Sunday in October.
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Jan 03, 2024
Global Impact
Global time standard, used for coordination across time zones.
Local to the UK, affects only national activities and schedules.
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Jan 03, 2024
Time Zone Offset
0 hours from the Prime Meridian.
+1 hour from GMT during its period of application.
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Jan 03, 2024
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GMT and BST Definitions
GMT
GMT is the mean solar time at the Royal Observatory in Greenwich, London.
The international conference call is scheduled for 3 PM GMT.
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Dec 19, 2023
BST
BST starts on the last Sunday in March and ends in October.
BST ends when the UK returns to GMT in autumn.
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Dec 19, 2023
GMT
GMT serves as the world's time standard.
Global stock markets synchronize their clocks with GMT.
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Dec 19, 2023
BST
BST is used to make better use of daylight.
BST helps conserve energy by reducing the need for artificial light in the evenings.
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Dec 19, 2023
GMT
GMT remains constant as the Prime Meridian's solar time.
Scientists often record data in GMT to avoid confusion with time zones.
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Dec 19, 2023
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BST
BST is the UK's daylight saving time, one hour ahead of GMT.
Clocks in the UK are set to BST during summer.
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Dec 19, 2023
GMT
GMT is used to coordinate time across different time zones.
Flight departures are listed in GMT for consistency.
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Dec 19, 2023
BST
BST shifts time to align with daylight during summer months.
During BST, evenings in the UK have more daylight.
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Dec 19, 2023
GMT
GMT does not change throughout the year.
Coordinated Universal Time (UTC) is based on GMT.
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Dec 19, 2023
BST
BST is specific to the UK and affects local schedules.
Television programming in the UK shifts to accommodate BST.
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Dec 19, 2023
GMT
The local time at the 0 meridian passing through Greenwich, England; it is the same everywhere
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Dec 13, 2023
Repeatedly Asked Queries
What is GMT?
Greenwich Mean Time is the mean solar time at the Prime Meridian in Greenwich, London.
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Jan 03, 2024
Why was BST introduced?
BST was introduced to make better use of natural daylight during summer.
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Jan 03, 2024
How does GMT differ from BST?
GMT is a constant time standard, while BST is GMT+1, applied as daylight saving time in the UK.
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Jan 03, 2024
Is GMT affected by daylight saving?
No, GMT remains the same throughout the year.
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Jan 03, 2024
When is BST observed?
BST is observed from the last Sunday in March to the last Sunday in October.
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Jan 03, 2024
What is BST?
British Summer Time is the UK's daylight saving time, one hour ahead of GMT.
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Jan 03, 2024
Why is GMT important for aviation?
GMT provides a consistent time reference for flight schedules and air traffic control.
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Jan 03, 2024
Do all countries use GMT?
GMT is a reference time, but not all countries adopt it for their standard time.
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Jan 03, 2024
How do international businesses manage GMT and BST differences?
They adjust meeting and operation times according to the relevant time zone.
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Jan 03, 2024
What is the time difference between GMT and BST?
BST is one hour ahead of GMT.
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Jan 03, 2024
How does BST impact daily life in the UK?
BST alters the timing of activities to align with longer daylight hours in summer.
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Jan 03, 2024
What happens when BST ends?
The UK reverts to GMT, setting clocks back by one hour.
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Jan 03, 2024
Does the change to BST affect international communication?
It can, as UK-based communications shift by one hour.
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Jan 03, 2024
How is GMT determined?
GMT is based on solar time at the Royal Observatory in Greenwich, London.
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Jan 03, 2024
Do other countries have a similar concept to BST?
Many countries observe daylight saving time, adjusting clocks similar to BST.
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Jan 03, 2024
Can GMT and BST be used interchangeably?
No, they differ by one hour during the BST period.
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Jan 03, 2024
Does BST apply to all of the UK?
Yes, the whole of the UK shifts to BST during summer.
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Jan 03, 2024
Are there any disadvantages to BST?
Adjusting to the time change can impact sleep patterns and schedules.
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Jan 03, 2024
How do electronic devices adjust for GMT and BST?
Most devices automatically update their clocks based on set time zone rules.
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Jan 03, 2024
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About Author
Written by
Shumaila SaeedShumaila Saeed, an expert content creator with 6 years of experience, specializes in distilling complex topics into easily digestible comparisons, shining a light on the nuances that both inform and educate readers with clarity and accuracy.
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