An image forming apparatus includes a toner cartridge, a developer, and a processor. The toner cartridge includes an accommodation container accommodating toner and a memory storing a first toner residual amount display threshold value. The developer performs development by the toner supplied from the toner cartridge. The processor calculates a second toner residual amount display threshold value based on a toner supply index, indicating an amount of the toner supplied to the developer from at least one toner cartridge used before a toner cartridge mounted on the image forming apparatus, and the first toner residual amount display threshold value. The processor outputs notification relating to a toner residual amount when a toner supply index indicating an amount of toner supplied to the developer from the toner cartridge mounted on the image forming apparatus exceeds the second toner residual amount display threshold value.