There are many factors that determine the actual drum life, such as temperature, humidity, type of paper, type of toner used, the number of pages per print job, etc. Under ideal conditions, the average drum life is estimated as approximately 20,000 pages. The actual number of pages that your drum unit will print may be significantly less that this estimate. Because we have no control, over the many factors that determine the acrual drum life, we cannot guarantee a minimum number of pages that will be printed by your drum. For best performance, use only genuine Brother toner. The printer should be used only in a clean, dust-free environment with adequate ventilation.