Image forming apparatus and image forming system

An image forming apparatus to which a plurality of toner containers including a first toner container in which toner in a first toner amount is accommodated and a second toner container in which toner in a second toner amount is accommodated are mountable, the image forming apparatus comprising:

• a mounting portion to which one toner container of the plurality of toner containers is mountable;
• an accommodating portion configured to accommodate the toner supplied from the one toner container mounted to the mounting portion;
• a detecting portion configured to output an output value depending on a remaining toner amount of the toner accommodated in the accommodating portion;
• and
• a controller,
• wherein the controller discriminates whether the one toner container used for first toner supply, from an unused state of the accommodating portion, which is toner supply from the one toner container to the accommodating portion is the first toner container or the second toner container by comparison between a threshold and the output value immediately after the first toner supply is made, and
• wherein in a case where the remaining toner amount of the accommodating portion corresponding to the output value in a predetermined timing before the first toner supply is made is a first remaining toner amount, the remaining toner amount of the accommodating portion based on a toner filling amount of the toner filled in the accommodating portion in the unused state and image information of an image printed from a time of the unused state to the predetermined timing is a second remaining toner amount, a condition in which the first remaining toner amount is larger than the second remaining toner amount is a first condition, and a condition in which the first remaining toner amount is smaller than the second remaining toner amount is a second condition,
• the controller sets the threshold so that the one toner container used for the first toner supply is easily discriminated as that the one toner container is the first toner container in a case where the first condition is satisfied than in a case where the second condition is satisfied.