- The continent of Africa is divided into four time zones. Those countries in the far west of the continent use Coordinated Universal Time, or UCT, known in Britain as Greenwich Mean Time or Zulu Time. The next time zone to the east is Western Africa Time, or WAT, and is one hour ahead of UCT, or UCT + 1. The last two African time zones are Central African Time, or CAT, which is UCT + 2, and Eastern African Time, or EAT, which is UCT + 3. African countries do not practice daylight saving time.
- The contiguous states of the USA are divided into four time zones. These are Eastern Standard Time, Central Standard Time, Mountain Standard Time and Pacific Standard Time, which are 5,6,7 and 8 hours behind UCT, or UCT - 5, UCT - 6, UCT - 7 and UCT - 8 hours, respectively.
Mainland Alaska is UCT - 9 hours, and Hawaii is UCT - 10 hours. During daylight saving time in the summer, American clocks are put forward one hour, making the difference between African and U.S. times one hour less. - To calculate what time it is in an African country, first look up the time zone that country is in and the time difference with UCT. In this example, use South Africa, which is UCT + 2. Check which state you are in and the time difference with UCT, for example Denver is Mountain time, which is UCT + 7. Add the two figures together and then add the product to your local Denver time. For example, if the time in Denver is 10:00 a.m., add 2 for South Africa and 7 for Denver, giving 19:00, which translates to 7:00 p.m. in South Africa, when converting from a 24-hour clock to a 12-hour clock.
- You can use this method of calculation to work out the time in any country in the world. All you need to know is the time zone and difference in hours from UCT. The term Greenwich Mean Time, or GMT, is still in common use in Britain and many of its ex-colonies. However, times have now been standardized to follow several atomic clocks, which are far more accurate, and is referred to as Coordinated Universal Time, or UCT.