The Meaning of Universal Time (UT)

When we need to define a time that does not depend on your location on the Earth, we use Universal Time (UT), which for our purposes is the same as Greenwich Mean Time (GMT) and Zulu (Z). This time is based on the current time at the prime meridian (0 degrees longitude) which runs through Greenwich, England. To convert from Universal Time to local time for U. S. time zones, subtract the following number of hours from Universal Time:

Time Zone


Daylight Savings

Eastern5 hours 4 hours
Central6 hours 5 hours
Mountain7 hours 6 hours
Pacific8 hours 7 hours

Click here for conversions from UT to Local Time at locations all over the world.
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