Generalized stacking fault energy and generalized planar fault energy in bcc iron were calculated via molecular dynamics using Finnis-Sinclair interatomic potential. Generalized stacking energy consideration were made on three most common slip system along <111> direction where as generalized planar fault energy was obtained for <111>(112) twin system. It is found that generalized stacking fault energy strictly depends on the considered slip system. On the other hand, present results of both generalized stacking fault and planar fault energies displayed a fair agreement with earlier literature results.