Provided is a method and apparatus for accurately estimating the volume of toner consumption of a laser printer by subtracting the volume of toner consumption corresponding to overlapping areas between adjacent bits of video data sequentially input by the bit from an average volume of toner consumption per bit. The apparatus includes an effective video data generator receiving video data and generating effective video data, a first storing unit receiving and temporarily storing the effective video data, and a toner consumption calculator receiving the effective video data from the first storing unit and calculating the volume of toner consumption per bit. The toner consumption calculator calculates the volume of toner consumption per bit by sequentially receiving the effective video data by the bit and subtracting the volume of toner consumption corresponding to overlapping areas between a bit and its adjacent bits from an average volume of toner consumption per bit.