The TN-11 Black toner cartridge yields up to 8,500 pages while each of the TN-11 Color toner cartridges yields up to 6,000 pages when printing at 5% coverage on A4/ Letter sized paper. When one of the toner cartridges begins run out, the message "Replace xxxx Toner (x)" appears on the operation panel (xxxx is the toner cartridge color). Replace the toner cartridge(s) as soon as the message prompting you to do so appears. The printer will stop operating if you do not replace the toner cartridge when required.