The ink supply level can be used to determine how soon an ink cartridge might need to be replaced. The ink supply level shows an estimate of the amount of ink remaining in the ink cartridges.
HP Customer Support
Checking Ink Levels for HP Officejet J3600 All-in-One Printer Series
Checking the estimated ink levels
Figure : Checking estimated ink levels
To check the ink levels from the control panel:
Press the down arrow () to highlight Tools and press OK.
Press the down arrow () to highlight Display Ink Gauge and press OK.The HP All-in-One displays a gauge that shows the estimated ink levels of all cartridges installed.
Press any button to return to the Tools menu.