The “Yield” is the amount of prints produced by the device or consumable. Each ink and toner cartridge will have an “average print yield” this is normally worked out at 5% coverage of ink & toner on the page. Most modern printers will have a display or function for you to look at your toner or ink level from your computer screen.
You can find out the yield of your ink or toner cartridge a number of ways. If you still have the original packaging this is the first and easiest way to find out the yield. It should be noted on the front or side of the container it was packaged in from the manufacturer.
Secondly you could look up the model of your ink or toner cartridge online directly on the manufacturers website. HP for example has a great user interface to find this information.
Many factors can affect the actual yields your ink or toner produces, these can be:
Printing in grey scale, Double sided printing, Printing Photo’s, Printing in “High Quality” mode.