Hi ken, If you print infrequently, the ink in an EcoTank ET-2800 will last for a very long time. We measure ink yield by pages, not time. T522 Refill bottles for the ET-2800 can be expected to yield around 4,500 black pages and 7,500 color pages. If you want to see details on our ISO test methods, visit the Epson support site. Regards, Mark - The Epson Team.