UTC offset
Difference between UTC and local standard time
The UTC offset is the difference in hours and minutes between Coordinated Universal Time (UTC) and the standard time at a particular place. This difference is expressed with respect to UTC and is generally shown in the format ±[hh]:[mm], ±[hh][mm], or ±[hh]. So if the time being described is two hours ahead of UTC (such as in Kigali, Rwanda [approximately 30° E]), the UTC offset would be "+02:00", "+0200", or simply "+02".
By convention, every inhabited place in the world has a UTC offset that is a multiple of 15 minutes but the majority of offsets are stated in whole hours. There are many cases where the national standard time uses a UTC offset that is not defined solely by longitude.
01Time zones and time offsets
A time zone is a geographical region in which residents observe the same standard time. Although nominally a new time zone is established every 15 degrees east or west of the prime meridian (meaning a one-hour change in the time), in practice local geographical or political considerations may vary its application. The most extreme example of this is time in China, which applies a single standard time offset of UTC+08:00 (eight hours ahead of Coordinated Universal Time), even though China spans five geographical time zones.
The UTC offset (or time offset) is an amount of time added to Coordinated Universal Time (UTC) time to specify the time at a given location.
Daylight saving time
Several regions of the world use daylight saving time (DST) and the UTC offset during this season is typically obtained by adding one hour to local standard time. Central European Time UTC+01:00 is replaced by Central European Summer Time UTC+02:00, and Pacific Standard Time UTC−08:00 is replaced by Pacific Daylight Time UTC−07:00.
02Illustrative examples
| Location | Longitude | UTC offset | When UTC time is 12:00, local time is: | When local time is 12:00, UTC time is: |
|---|---|---|---|---|
| Accra, Ghana | 0° 12′ W | UTC+00:00 | 12:00 | 12:00 |
| Mogadishu, Somalia | 45° 20′ E | UTC+03:00 | 15:00 | 09:00 |
| Dhaka, Bangladesh | 90° 23′ E | UTC+06:00 | 18:00 | 06:00 |
| Koror, Palau | 134° 29′ E | UTC+09:00 | 21:00 | 03:00 |
| Suva, Fiji | 178° 27′ E | UTC+12:00 | 00:00 | 00:00 |
| Honolulu, United States | 157° 51′ W | UTC−10:00 | 02:00 | 22:00 |
| Guatemala City, Guatemala | 90° 32′ W | UTC−06:00 | 06:00 | 18:00 |
| Brasília, Brazil | 47° 53′ W | UTC−03:00 | 09:00 | 15:00 |
Sources and credits
This article is adapted from the Wikipedia article “UTC offset”, written by its contributors and licensed under CC BY-SA 4.0. Fathomly has changed the layout, removed citation markers, navigation and maintenance notices, and adjusted punctuation. This adapted version is shared under the same license. For references, see the original article.
Images, from Wikimedia Commons:
- World Time Zones Map.png by UnaitxuGV, Heitordp and others, Public domain
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