An image forming apparatus includes an image forming unit, a fixing unit having a heater, a temperature detection unit, a power control unit, and a conveyance control unit that controls conveying a recording material. The conveyance control unit executes, when the maximum power is greater than a threshold power, a first mode where conveyance is performed according to a time, and executes, in a case where the maximum power is less than the threshold power, a second mode where conveyance is performed according to the detected temperature. The power control unit sets a larger value to the threshold power when an option device is connected to the image forming apparatus as compared to when the option device is not connected to the image forming apparatus.