I've found this site:
Time Zone Converter
To be of help in the past. It even remembers your setting so for instance if there is a map test at 2pm EST on the 3rd I can check that to see what it is for me, and then a couple of days later load the site again to check a test for 6pm EST on the fourth.
Works great when thread posters in the Tester's Guild follow the rules and post using the one Time Zone.