Image forming apparatus permitting whether or not input image can be formed as desired to be known

An image forming apparatus, comprising:

• a memory for storing document image information;
• a printing unit for forming and outputting an image onto a sheet based on the image information stored in said memory;
• a calculation unit for calculating the necessary number of sheets based on the number of documents and the number of printing for each document;
• and
• a detector for detecting the remaining number of stored sheets, wherein
• if the number of sheets calculated by the calculation unit is larger than the remaining number of sheets detected by the detector, a warning is issued and the operation of outputting sheets is delayed.

A method of forming an image, comprising the steps of:

• storing document image information;
• forming an image on a sheet for printing based on said document image information;
• calculating the necessary number of sheets based on the number of documents and the number of printing;
• detecting the remaining number of stored sheets;
• and
• issuing a warning if the calculated number of sheets is larger than the remaining number of sheets and delaying outputting of a sheet.