An image forming apparatus, comprising: an in-situ refillable upper toner hopper; a developer to develop an electrostatic latent image formed on a photosensitive drum, using toner, the developer comprising a lower toner hopper to receive the toner from the in-situ refillable upper toner hopper via a mechanical toner transport; a cleaning member to remove waste toner from a surface of the photosensitive drum; a waste toner hopper to collect the waste toner from the cleaning member; non-volatile memory; and at least one processor, in electrical communication with the non-volatile memory, to: count a number of times the lower toner hopper receives toner from the in-situ refillable upper toner hopper, calculate an estimate of toner volume transferred from the lower toner hopper to the surface of the photosensitive drum, determine an amount of toner consumed from the in-situ refillable upper toner hopper based on the number of times the lower toner hopper receives toner from the in-situ refillable upper toner hopper and the estimate of toner volume transferred from the lower toner hopper to the surface of the photosensitive drum, and generate an upper toner hopper refill notification when the amount of toner consumed from the in-situ refillable upper toner hopper is determined to exceed a threshold value. an in-situ refillable upper toner hopper; a developer to develop an electrostatic latent image formed on a photosensitive drum, using toner, the developer comprising a lower toner hopper to receive the toner from the in-situ refillable upper toner hopper via a mechanical toner transport; a cleaning member to remove waste toner from a surface of the photosensitive drum; a waste toner hopper to collect the waste toner from the cleaning member; non-volatile memory; and at least one processor, in electrical communication with the non-volatile memory, to: count a number of times the lower toner hopper receives toner from the in-situ refillable upper toner hopper, calculate an estimate of toner volume transferred from the lower toner hopper to the surface of the photosensitive drum, determine an amount of toner consumed from the in-situ refillable upper toner hopper based on the number of times the lower toner hopper receives toner from the in-situ refillable upper toner hopper and the estimate of toner volume transferred from the lower toner hopper to the surface of the photosensitive drum, and generate an upper toner hopper refill notification when the amount of toner consumed from the in-situ refillable upper toner hopper is determined to exceed a threshold value. count a number of times the lower toner hopper receives toner from the in-situ refillable upper toner hopper, calculate an estimate of toner volume transferred from the lower toner hopper to the surface of the photosensitive drum, determine an amount of toner consumed from the in-situ refillable upper toner hopper based on the number of times the lower toner hopper receives toner from the in-situ refillable upper toner hopper and the estimate of toner volume transferred from the lower toner hopper to the surface of the photosensitive drum, and generate an upper toner hopper refill notification when the amount of toner consumed from the in-situ refillable upper toner hopper is determined to exceed a threshold value.