Quoted from MAL:
According to the tweet of Irie Yasuhiro, he is currently working on the storyboard of Fullmetal Alchemist: Brotherhood based on Arakawa Hiromu’s manuscripts of the manga up to the final chapter. He was overwhelmed by the thick storyline of the finale. He said “Laugh or cry, two months left.” The voice and sound dubbing of episode 58 and the film editing of episode 61 have done so far.
Source: Irie’s tweet
Based on MAL’s ep count, FMA:Brotherhood will be having a total of 63 episodes.