An image forming system capable of determining whether a detected communication speed reaches a communication speed needed for printing the received printing data successfully according to printing ability of an image forming apparatus. A detection unit detects a communication speed of wireless communication executed between the image forming apparatus and an information processing apparatus. An obtainment unit obtains a communication speed needed so that the image forming apparatus successfully prints the print data that is received by using wireless communication according to a printing ability of the image forming apparatus. A determination unit determines whether the communication speed detected by the detection unit reaches the communication speed obtained by the obtainment unit or not. A notification unit notifies a user that the detected communication speed is insufficient when the determination unit determines that the communication speed detected by the detection unit does not reach the communication speed obtained by the obtainment unit.