-It is the standard of the industry established by the major manufacturers: HP, Canon, Xerox etc. to state a page yield for toner cartridges. -They determined that 5% page coverage is the standard to determine just how many pages a toner cartridge will produce. If they state 2,000 pages, then that means you will get 2,000 pages only if the page has 5% of the page with words on it! -If you have a solid BLACK line or pie graft on the page, it will take a LOT more toner to fill that in and you WILL NOT get anywhere near 2,000 pages out of that toner cartridge. -Other factors are how dark you set your printer to print.