EST is GMT-5.
PST is GMT-8.
Not to insult anyone here, but it surprises me how many people in the game don't know how to work with timezones. Whenever there's a maintenance window, people are always saying "What time is that?"
There are five timezones in the US, but nobody generally worries about Alaska/Hawaii, so we'll say four. Square makes all its US announcements in Pacific Standard Time. If you're in Mountain, add 1. If you're in Central, add 2. If you're in Eastern, add 3. It's not hard. I can't believe I see some people trying to derive it from the 24-hour time format that Square uses... >.> It's not that complicated.