The present jig for guiding placement of femoral component of the implant in a knee replacement surgery (J) is a pre-assembled Jig (J) which ensures precision fit femoral implant for knee replacement based on difference of cuts in millimeters instead of the usual angle measurement in degrees. It avoids intrusion of the intramedullary canal substantially decreasing the risks of embolism. It enables the surgeon to use precise values of depth of cuts obtained from a system for obtaining optimum fit implant as described in patent application number 3896/MUM2015. This enables the surgeon to control precisely the placement of the implant in terms of flexion or extension, varus or valgus, internal or external rotation It also enables precise placement of the four-in-one cutting block simultaneously with the distal femur cut ensuring precise placement of knee femoral component of the knee implant. This reduces efforts and time taken during the surgery.