Toner and ink cartridges are rated by manufacturers for printing a standard printed page of text. They estimate that a page of text (no photos or graphics) will use toner / ink on about 5% of the paper. 100% coverage would mean the page is covered completely with ink or toner. For example, it would be solid black if you were using black toner at 100% coverage. So, when they rate a cartridge at “2,500 yield”, it means that about 2,500 pages of text at 5% coverage can be printed before it runs out of ink or toner. However, please note that many print jobs vary and actually use more than 5% coverage. For example, photos and graphics use quite a bit more ink and toner.