A method and apparatus for measuring the volume of toner consumed in a printer using a beam modulation technique, wherein: printing data, which is input in units of multiple numbers of bits per pixel in synchronization with a video clock signal, is converted into bit values corresponding to equal sections into which each pixel is divided depending on the number of bits per pixel. Next, a carry value is obtained by summing the bit values corresponding to the number of converted sections of printing data with the previous bit value. Then, the carry value obtained in this manner is counted. The counted carry value is multiplied by a predetermined value, and the volume of toner consumed is measured using the resulting product.