See, that’s just a great question. Congratulations on being a smart person who cares about the right things in life! Oktoberfest 2014 begins Saturday, September 20th, and runs through Sunday, October 5th, 2014. You are now an informed stein drinker.
Now that you know that and are prepared to lederhose (definitely a verb), here are some things that might help:
How to do Oktoberfest in Munich
Some really interesting numbers reflecting how much is drank, eaten, lost, and stolen in Munich every year
And if you're standing there on a bench drinking beer and cheers-ing, asking yourself "when is Oktoberfest?", you're probably also asking, "where can I celebrate Oktoberfest?" Well, here are some very handy Oktoberfest event calendars listing out all the must-hit consumption cabals in some of our cities, including New York, San Francisco, Chicago, and LA.