1. To reckon wrongly
   "I had miscalculated his determination";
   - misestimate
    
2. (arithmetic) calculate incorrectly
   "I miscalculated the number of guests at the wedding";
   - misestimate

Derived forms: miscalculated, miscalculates, miscalculating

Type of: calculate, cipher, compute, cypher, figure [N. Amer], misjudge, reckon, work out