A method and apparatus for dimensioning and, optionally, weighing an object. A platform with a surface is used for supporting an object. A user selects between two different dimensioning devices of the apparatus. The first device employs three distance sensors to determine a distance between each of the distance sensors and a side of an object. The second device includes a movable gate which is passed over and about an object or objects on the platform. Sensor arrays, such as paired, aligned light emitter and receiver arrays, are used in combination with a plurality of sensed gate positions to determine the dimensions of the object(s) as the gate passes around the object(s) based on whether or not light from an emitter on one side of the gate reaches a light receiver on another, opposing side of the gate. A conveyorized dimensioning system employing multi-row sensor arrays is also disclosed.