Image forming systems and methods of forming an image are described. According to one exemplary aspect of the invention, a system includes a consumable monitoring device which provides a current amount of a consumable, such as toner. The system of this aspect also includes a memory device configured to store historical information regarding the consumable. A processor provides a requirement amount of the consumable and statistically modifies at least one of the requirement amount and the current amount using the historical information. Exemplary statistical modification uses a ratio of an estimation of a number of pixels within previous image jobs and the actual number of pixels imaged within previous jobs. Thereafter, the processor analyzes the requirement amount with respect to the current amount to determine the probability that an image job will be successfully imaged. In one arrangement, a confidence value is utilized for statistical modification. In addition, the historical information may be weighted. Additional aspects of the invention are also disclosed.