A majority. Since there are currently 538 votes, 270 votes are required.
271
You must receive a majority of votes by the electoral college.
A majority of votes by the electoral college :)
The Electoral College
John Quincy Adams was the only President who did not receive a majority of the electoral votes. There was a dispute over the credentials of some of the electors in 1876, but after the dispute was settled, Rutherford Hayes won a majority of the electoral vote.
Andrew Jackson
President Van Buren lost that election 60 to 234.
President Obama won Washington's 12 electoral votes in the 2012 presidential election.
George Washington
George Washington received 100% of the electoral votes and was unanimously elected President in 1789 and 1792.
In order to elect a president , one candidate must receive more than half the votes. If more than two candidates receive votes, then it is possible that no one will get the required majority and you could say the electoral college is deadlocked. As of 2014, with the total of electoral votes being 538, it is also possible that two candidates could each receive 269. This tie vote would sent the election to the US Congress.
The winning candidate has to have a simple majority of votes from the electoral college. In other words, the candidate will only need to win by ONE electoral vote to become the president. He must receive a simple majority of the 535 votes in the electoral college.