Page yield for toner cartridges is measured based off 5% page coverage.
On average, printed pages will have approximately 5% of their page covered with laser toner. If pages have minimal text, this number will be lower, but if large diagrams or charts are printed, it will be higher. Examples can be found below.
The amount of toner powder in each cartridge is measured based on how many pages it can print with 5% of the page covered. This value can change with how much toner is used per print.
Examples of page coverage:
