A Football Association panel added a match to the ban because it felt the appeal was unlikely to succeed.
Ferdinand's decision to challenge the charge freed him to play in Wednesday's Carling Cup win over Manchester City.
The 31-year-old, who has made only 10 appearances for his club so far this season, will now sit out Sunday's Premier League encounter with Arsenal, followed by February's matches against Portsmouth, Aston Villa and Everton.
I don't think there was ever the chance of him being successful Joebloggs21 However, he remains available for the first leg of the Red Devils' Champions League tie against AC Milan at the San Siro on 16 February and the Carling Cup final against Aston Villa on 28 February.
The match against Hull was Ferdinand's first for United in three months after his recovery from a calf injury.
His tangle with Fagan in the penalty area was missed by referee Steve Bennett during the match, but the panel reached their decision after studying television replays.
Ferdinand's ban poses problems for manager Sir Alex Ferguson at the centre of his defence with fellow centre-back John O'Shea likely to miss the rest of the season with a leg problem.
Serbia international Nemanja Vidic, who was on the bench on Wednesday, is only just returning from a nerve injury picked up in the warm up before the FA Cup match against Leeds on 3 January.
And Fulham defender Chris Smalling, who was also in attendance at Old Trafford for the semi-final victory over their city rivals, only joins up with his new team-mates at the start of the 2010-11 season.