Samsung SL-M4020ND-TAA - Manual (Page 59)

Storing the toner cartridge
59 3. Maintenance
3
Estimated cartridge life
Estimated cartridge life (the life of the toner cartridge yield) depends on the
amount of toner that print jobs require. The actual print yield may vary
depending on the print density of the pages you print on, operating
environment, percentage of image area, printing interval, media type and/or
media size. For example, if you print a lot of graphics, the consumption of the
toner is higher and you may need to change the cartridge more often.