Abstract: Disclosed is a method and system for finding a relationship between a tool-frame of a tool attached at a wrist of a robot and robot kinematics of the robot using an external camera. The position and orientation of the wrist of the robot define a wrist-frame for the robot that is known. The relationship of the tool-frame and/or the Tool Center Point (TCP) of the tool is initially unknown. For an embodiment, the camera captures an image of the tool. An appropriate point on the image is designated as the TCP of the tool. The robot is moved such that the wrist is placed into a plurality of poses. Each pose of the plurality of poses is constrained such that the TCP point on the image falls within a specified geometric constraint (e.g. a point or a line). A TCP of the tool relative to the wrist frame of the robot is calculated as a function of the specified geometric constraint and as a function of the position and orientation of the wrist for each pose of the plurality of poses.