A method for determining an amount of ink that has been used by an inkjet printhead cartridge that is installed in an inkjet printer connected to a network of inkjet printers (12a, 12b, 12c), characterized in that the method comprises: storing a printhead identification value in a printhead memory device of the inkjet printhead cartridge; and providing a processor in the inkjet printer for executing instructions for: accessing the printhead identification value from the printhead memory device and storing the printhead identification value in a memory device of the inkjet printer; communicating over the network with one or more other inkjet printers (12b, 12c) connected to the network; receiving other ink dot count values from the one or more other inkjet printers (12b, 12c) connected to the network, wherein the other ink dot count values received from the one or more other inkjet printers (12b, 12c) are associated with the printhead identification value stored in the memory device of the inkjet printer; storing the other ink dot count values having highest value as an ink dot count value in the memory device of the inkjet printer; and as printing is being performed by the inkjet printer, updating the ink dot count value stored in the memory device of the inkjet printer by incrementing the ink dot count value stored in the memory device of the inkjet printer proportional to a number of ink dots ejected from the inkjet printhead cartridge. storing a printhead identification value in a printhead memory device of the inkjet printhead cartridge; and providing a processor in the inkjet printer for executing instructions for: accessing the printhead identification value from the printhead memory device and storing the printhead identification value in a memory device of the inkjet printer; communicating over the network with one or more other inkjet printers (12b, 12c) connected to the network; receiving other ink dot count values from the one or more other inkjet printers (12b, 12c) connected to the network, wherein the other ink dot count values received from the one or more other inkjet printers (12b, 12c) are associated with the printhead identification value stored in the memory device of the inkjet printer; storing the other ink dot count values having highest value as an ink dot count value in the memory device of the inkjet printer; and as printing is being performed by the inkjet printer, updating the ink dot count value stored in the memory device of the inkjet printer by incrementing the ink dot count value stored in the memory device of the inkjet printer proportional to a number of ink dots ejected from the inkjet printhead cartridge. accessing the printhead identification value from the printhead memory device and storing the printhead identification value in a memory device of the inkjet printer; communicating over the network with one or more other inkjet printers (12b, 12c) connected to the network; receiving other ink dot count values from the one or more other inkjet printers (12b, 12c) connected to the network, wherein the other ink dot count values received from the one or more other inkjet printers (12b, 12c) are associated with the printhead identification value stored in the memory device of the inkjet printer; storing the other ink dot count values having highest value as an ink dot count value in the memory device of the inkjet printer; and as printing is being performed by the inkjet printer, updating the ink dot count value stored in the memory device of the inkjet printer by incrementing the ink dot count value stored in the memory device of the inkjet printer proportional to a number of ink dots ejected from the inkjet printhead cartridge.