GMT, or Greenwich Mean Time, is the time zone that is calculated based on it’s location of zero degrees longitude. GMT is also sometimes referred to as Greenwich Meridian Time because it runs through Greenwich England, on the prime meridian. The prime meridian, along with the equator, help to calculate time zones, because they divide the hemispheres of the world. Converting GMT time to CST, or Central Standard Time, can be done by using the right formula or tools, such as converters.
Convert the current GMT to a 24-hour scale. Although many time zones are calculated using the 12-hour scale, it’s easier to convert between time zones that have such a large difference using the 24-hour scale. For example, if it’s 5 p.m. GMT time, it would actually be 17:00 hours on a 24-hour scale.
Count backward six hours to find the CST from your GMT time. If your current GMT time is 17:00 hours, your CST would actually be 11:00 hours or 11 a.m. Central Standard Time is 6 hours behind the GMT time.
Calculate the time change using the 12-hour scale, by counting back 6 hours. For example if it’s 9 p.m. GMT time, it’s 3 p.m. CST. Because the time zones are so far apart, you may find that depending on your hours of calculation, it may be a day earlier CST than it is GMT time.
Use an online time zone converter (see Resources). With a converter, you can look up the current time for countries all over the world, or you can use the conversion tool. To convert GMT time to CST, select your location within the CST conversion slot and hit calculate. The calculation will be given in a 24-hour scale.