An image forming system includes: a server accepting a print job from a client apparatus; and an image forming apparatus receiving an order for the print job from the server, the image forming apparatus including: a sheet feeding tray accommodating a sheet; a hardware processor determining to receive an order for a print job accepted by the server when a first and second conditions are satisfied; and an image former forming a page image based on the print job accepted by the server and a page image based on the print job being accepted specifying the sheet of the same size as that of the sheet specified, by allocating the page images in parallel to the sheet of twice the size of the sheet specified, when it is determined by the hardware processor that the order for the print job accepted by the server is received.