I'm with a LOT of other people. I am currently under EDT, and the map and reality agree that I am -4 (until DST goes out of effect). But I answered -5. The full specification of my TZ ID is EST5EDT. Everybody thinks of it as 5 h behind Greenwich; hence conceptually it is 5 hr behind GMT or UTC "sort of" (i.e., the EST base spec is). I am OCD and perhaps overthink questions, but you are going to get other "wrong" votes. EST5EDT is a VERY popular TZ.