Image forming apparatus that corrects image forming condition

An image forming apparatus comprising:

• an image forming unit configured to form an image on an image carrier, using a plurality of colors;
• a detection unit configured to detect a detection pattern formed by the image forming unit;
• a first correction unit configured to obtain a measurement value of a correction amount to be used for correcting an image forming condition based on a detection result by the detection unit, and correct the image forming condition based on the measurement value;
• a second correction unit configured to obtain a variation value by a prediction calculation at a predetermined timing, obtain a prediction value by accumulating the variation value since the first correction unit performed the correction, and correct the image forming condition based on the prediction value, the variation value being a estimated value of the correction amount;
• and
• a determination unit configured to obtain an evaluation value related to a prediction error and used to determine a correction timing by the first correction unit based on the variation value since the first correction unit performed the correction, and determine, based on the evaluation value, the correction timing by the first correction unit.