What Is the Difference Between UTC and GMT?
Two common time abbreviations are often used interchangeably. Learn what each one means and how they are actually used.
Similar Clocks, Different Concepts
Greenwich Mean Time (GMT) is historically related to the mean solar time at Greenwich, while Coordinated Universal Time (UTC) is the modern standard the world uses to coordinate time. In everyday use, the two usually display the same time, but they are not exactly the same concept.
GMT is also commonly used as a time zone name for certain regions, whereas UTC is more often used as the baseline for expressing global time offsets.
Is London Time Always GMT?
No. The United Kingdom uses GMT in winter and usually British Summer Time (BST) in summer, which is one hour ahead of UTC. Therefore, arrangements involving London should be checked against a specific date rather than equating London with GMT year-round.
When sharing times, writing out the city, date, and time zone is clearer than relying on a single abbreviation that may be misunderstood.
Put it into practice
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