A method and system to provide improved accuracies in multi jointed robots through kinematic robot model parameters determination are disclosed. The present invention calibrates multi-jointed robots by using the chain rule for differentiation in the Jacobian derivation for variations in calculated poses of reference points of a reference object as a function of variations in robot model parameters. The present invention also uses two such reference objects and the known distance therebetween to establish a length scale, thus avoiding the need to know one link length of the robot. In addition, the present invention makes use of iterative methods to find the optimum solution for improved accuracy of the resultant model parameters. Furthermore, the present invention provides for determination of the end joint parameters of the robot, including parameters defining the tool attachment mechanism frame, which allows for interchange of tools without subsequent calibration.