Source : Webster's Revised Unabridged Dictionary (1913)

Miscalculate \Mis*cal"cu*late\, v. t. & i.
   To calculate erroneously; to judge wrongly. --
   {Mis*cal`cu*la"tion}, n.

Source : WordNet®

miscalculate
     v 1: judge incorrectly; "I had misestimated his determination"
          [syn: {misestimate}]
     2: calculate incorrectly; "I miscalculated the number of guests
        at the wedding" [syn: {misestimate}]