HP LaserJet 8000 Multifunction Printer series - Manual (Page 138)

Chapter 4 Printer Maintenance 138
Managing the Toner Cartridge
Toner Cartridge Life Expectancy
The life of the toner cartridge depends on the amount of toner that print jobs
require. When printing text at 5% coverage, an HP toner cartridge lasts an
average of 15,000 pages. (A typical business letter is about 5% coverage.)
This assumes that print density is set to 3 and EconoMode is off. (These are
the default settings.)