Patent ID: 8638454

Claim:
An image forming apparatus comprising: a reading section configured to read an original document; a printing section configured to perform duplex printing including printing N sheets on first sides thereof and subsequently printing M sheets on second sides thereof when printing an image of the original document read by the reading section, wherein M is equal to or smaller than N; a storage section configured to store therein an initial time, a plurality of time coefficients for respective copy setting items which affect a preparation time required to generate print data, and a threshold value; a determination section configured to calculate a preparation time required to generate print data by multiplying the initial time by respective time coefficients for copy setting items set as a copy setting, and configured to determine the value of N, wherein before starting the duplex printing, the determination section is configured to determine a first value as the value of N when the preparation time is smaller than the threshold value and determine a second value which is smaller than the first value as the value of N when the preparation time is equal to or larger that the threshold value; and a control section configured to control the printing section to perform the duplex printing in accordance with the value of N which is determined by the determination section before starting the duplex printing.