Radial runout in milling arises from the misalignment between the geometric axis of the cutter and its axis of rotation when it is mounted in the machine’s spindle with a holder. Runout results in the chip thickness distribution for every tooth being different. Since forces in the milling process are a direct function of the chip thickness distribution, a change in this distribution due to runout also loads every tooth differently. Moreover, since the stability of the cutting process is also governed by the dynamic chip thickness, runout also affects stability. Since runout can cause premature damage to the tool and destabilize an otherwise stable process, it is necessary to measure it. Traditional methods rely on using a dial gauge. However, this method cannot be used to measure speed-dependent dynamic runout, which necessitates the use of non-contact methods. This paper introduces the use of a new vision-based method to measure static and dynamic runout. The central idea is to track the edge of each tooth as it rotates using an edge detection and tracking scheme applied on individual frames of a video recording of the rotating tool. The proposed method is benchmarked with dial gauge measurements for the static case and measurements made with a laser displacement sensor for the speed-dependent case. Measured runout is incorporated in force and stability models to show its influence on cutting forces and stability of a representative end milling process.