Find out the longitude of your location in degrees, multiply by 24 and divide by 360. This gives the difference in hours between your location and the Prime (or Greenwich) Meridian. For example;
1. Longitude 10 degrees East: 10*24/360 = 0.67 hours approx., = 40 minutes.
Local time would be GMT plus 40 minutes (e.g, if the time was 11.20 GMT, local time would be 12.00);
2. Longitude 15 degrees West: 15*24/360 = 1 hour.
Local time would be GMT minus 1 hour (e.g, if the time was 11.00 GMT, local time would be 10.00).
To convert BST (British Summer Time) to GMT (Greenwich Mean Time), you simply subtract 1 hour since GMT is one hour behind BST. Take the BST time and deduct one hour to get the equivalent time in GMT.
To convert a time given in GMT to India time, add 5½ hours.
GMT + 1 hr. = BST (spring ahead)
During summer, GMT + 1 hour. (GMT is the Wikianswers base time)
10 AM PDT is 5 PM GMT. Pacific Daylight Time (PDT) is 7 hours behind Greenwich Mean Time (GMT). Therefore, when it is 10 AM in PDT, you add 7 hours to convert it to GMT.
The UK and Morocco.
7:30 PM PST is 3:30 AM GMT the next day. Pacific Standard Time (PST) is 8 hours behind Greenwich Mean Time (GMT). To convert from PST to GMT, you add 8 hours to the PST time.
10:30 AM GMT is 11:30 AM CET. Central European Time (CET) is one hour ahead of Greenwich Mean Time (GMT). Therefore, to convert from GMT to CET, you simply add one hour.
6.30 EST in Australia = 20.30 GMT 6.30 EST in America = 11.30 GMT
5:32 PM GMT or 17:32 UTC (coordinated universal time)
1700 GMT is 11:00 AM Central Time. Central Time is 6 hours behind GMT, so you would subtract 6 hours from 17:00 GMT to get the local time in Central Time.
16:00 (Local time - [GMT +2])/ 10:00 (US Eastern time - [GMT -4]).