Abstract: A system and method for measuring the elongation, or stretch, of a modular plastic conveyor belt. The belt-stretch measuring system measures stretch as the ratio less one of an actual belt travel distance or actual belt speed to an expected belt travel distance or expected belt speed for a new, unstretched belt. The actual belt travel distances or actual belt speeds are measured by sensors. The expected belt travel distances or expected belt speeds are calculated from the pulse outputs of encoders measuring the rotation of sprockets engaging the conveyor belt and from the known number of teeth on the sprockets. Actual belt pitch and catenary sag are also calculated.