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Since radio signals can cross multiple time zones and the international date line, some worldwide standard for time and date is needed. This standard is coordinated universal time, abbreviated UTC. This was formerly known as Greenwich mean time (GMT). Other terms used to refer to it include 'Zulu time' (after the 'Z' often used after UTC times), 'universal time,' and 'world time.'
UTC is used by international shortwave broadcasters in their broadcast and program schedules. Ham radio operators, shortwave listeners, the military, and utility radio services are also big users of UTC. All of the times and dates found here at DXing.com at UTC unless otherwise indicated.
Greenwich mean time was based upon the time at the zero degree meridian that crossed through Greenwich, England. GMT became a world time and date standard because it was used by Britain's Royal Navy and merchant fleet during the nineteenth century. Today, UTC uses precise atomic clocks, shortwave time signals, and satellites to ensure that UTC remains a reliable, accurate standard for scientific and navigational purposes. Despite the improvements in accuracy, however, the same principles used in GMT have been carried over into UTC.
UTC uses a 24-hour system of time notation. '1:00 a.m.' in UTC is expressed as 0100, pronounced 'zero one hundred.' Fifteen minutes after 0100 is expressed as 0115; thirty-eight minutes after 0100 is 0138 (usually pronounced 'zero one thirty-eight'). The time one minute after 0159 is 0200. The time one minute after 1259 is 1300 (pronounced 'thirteen hundred'). This continues until 2359. One minute later is 0000 ('zero hundred'), and the start of a new UTC day.
To convert UTC to local time, you have to add or subtract hours from it. For persons west of the zero meridian to the international date line (which includes all of North America), hours are subtracted from UTC to convert to local time. Below is a table showing the number of hours to subtract from local time zones in North America in order to convert UTC to local time:
The second table is direct conversion from UTC to U.S.A. timezones.
A major source of confusion when using UTC is that the date also follows UTC. Suppose your local time zone is Central standard, and you want to hear a shortwave program scheduled to be broadcast at 0400 UTC Saturday. You do the math, and find that 0400 UTC is equal to 10:00 p.m. Central standard time. If you tune in at 10:00 p.m. on Saturday, however, you won't hear the program. Since the date is also UTC, you need to listen at 10:00 p.m. Friday to hear the program.
To hear the latest time in UTC, you can tune to stations WWV, in Fort Collins, Colorado and WWVH, Kauai, Hawaii on 2500, 5000, 10000 and 15000 kHz to hear the time announced in UTC each minute. WWV uses a man's voice to give the time, while WWVH uses a female voice. If you live in the central or eastern United States, and those frequencies aren't usable, you can tune to station CHU, in Ottawa, Ontario, Canada on 3330,
©1999-2009 by Universal Radio Research. All rights reserved.
Time Difference. Eastern Daylight Time is 4 hours behind of Universal Time Coordinated 2:00 am.
7pm Utc To East
- Daylight Saving Time used for Eastern Standard Time (EST), for details check here. Scale: 00:00 00:05 00:10 00:15 00:20 00:25. Is local time not Right?
- Converting UTC to EST. This time zone converter lets you visually and very quickly convert UTC to EST and vice-versa. Simply mouse over the colored hour-tiles and glance at the hours selected by the column. UTC stands for Universal Time. EST is known as Eastern Standard Time. EST is 4 hours behind UTC.
- The Time Zone Converter converts times instantly as you type. Convert between major world cities, countries and timezones in both directions.
- UTC to EST converter to convert between UTC (Coordinated Universal Time) and EST (Eastern Standard Time). Convert any UTC time to EST quickly and accurately.
Normally time is shown as Hours:Minutes
There are 24 Hours in a Day and 60 Minutes in each Hour.
Showing the Time
There are two main ways to show the time: '24 Hour Clock' or 'AM/PM':
- the 12 Hours running from Midnight to Noon (the AM hours), and
- the other 12 Hours running from Noon to Midnight (the PM hours).
Like this (try the slider):
Latin for 'after midday'
Midnight to Noon
24 Hour Clock:
12:00 to 23:59
*Is that spelled 'Meridiem' or 'Meridian'? See here.
Converting AM/PM to 24 Hour Clock
Add 12 to any hour after Noon (and subtract 12 for the first hour of the day):
For the first hour of the day (12 Midnight to 12:59 AM), subtract 12 Hours
From 1:00 AM to 12:59 PM, no change
From 1:00 PM to 11:59 PM, add 12 Hours
Converting 24 Hour Clock to AM/PM
For the first hour of the day (00:00 to 00:59), add 12 Hours, make it 'AM'
From 01:00 to 11:59, just make it 'AM'
From 12:00 to 12:59, just make it 'PM'
Utc To Est January
From 13:00 to 23:59, subtract 12 Hours, make it 'PM'
Comparison ChartHere is a side-by-side comparison of the 24 Hour Clock and AM/PM:
Example: 10 minutes past
|AM / PM|
24 Hour Clock
|AM / PM|
|00:00||12 Midnight||00:10||12:10 AM|
|01:00||1:00 AM||01:10||1:10 AM|
|02:00||2:00 AM||02:10||2:10 AM|
|03:00||3:00 AM||03:10||3:10 AM|
|04:00||4:00 AM||04:10||4:10 AM|
|05:00||5:00 AM||05:10||5:10 AM|
|06:00||6:00 AM||06:10||6:10 AM|
|07:00||7:00 AM||07:10||7:10 AM|
|08:00||8:00 AM||08:10||8:10 AM|
|09:00||9:00 AM||09:10||9:10 AM|
|10:00||10:00 AM||10:10||10:10 AM|
|11:00||11:00 AM||11:10||11:10 AM|
|12:00||12 Noon||12:10||12:10 PM|
|13:00||1:00 PM||13:10||1:10 PM|
|14:00||2:00 PM||14:10||2:10 PM|
|15:00||3:00 PM||15:10||3:10 PM|
|16:00||4:00 PM||16:10||4:10 PM|
|17:00||5:00 PM||17:10||5:10 PM|
|18:00||6:00 PM||18:10||6:10 PM|
|19:00||7:00 PM||19:10||7:10 PM|
|20:00||8:00 PM||20:10||8:10 PM|
|21:00||9:00 PM||21:10||9:10 PM|
|22:00||10:00 PM||22:10||10:10 PM|
|23:00||11:00 PM||23:10||11:10 PM|
Midnight and Noon
'12 AM' and '12 PM' can cause confusion, so we prefer '12 Midnight' and '12 Noon'.
What Day is Midnight?
Midnight has another problem: there is nothing to tell us 'is this the beginning or ending of the day'.
Imagine your friends say they are leaving for holiday at 'midnight' on 12th March, what day should you arrive to say goodbye?
7pm Utc To Est
Do you get there on the 11th (assuming they leave at the very start of the 12th), or the 12th (assuming they leave at the end of the 12th)?
It is better to use:
- 11:59 PM or 12:01 AM, or
- 23:59 or 00:01 (24-Hour Clock)
which the railroads, airlines and military actually do.
So, when you see something like 'offer ends midnight October 15th' tell them to use one minute before or after so there is no confusion!
Footnote on 'Meridiem' vs 'Meridian'
Should 'AM' be 'ante meridiem' or 'ante meridian' (likewise for PM)?
The official (according to an American, Australian and British dictionary I checked), and most common spelling for AM is 'ante meridiem' which is a Latin phrase. I recommend that spelling!
But people sometimes use the phrase 'ante meridian' (a 'meridian' in this case refers to an imaginary line in the sky when the sun is at its highest point).