1024*768 although i i could make it higher if i could be bothered. This 21 inch monster CRT (Compaq P110) does all kinds of resolutions and refresh rates. At work I have 2 flat monitors, one is a 24 inch, the other a 19 inch. And 2 computers, one a HP DX2000, the other an ancient Compaq C500. The DX2000 runs XP and has a dual-monitor card, and the C500 runs Win2000 and only does one monitor. There is a switch to select which computer is connected to the 19 inch monitor. Can't remember the exact resolutions, but I made it so the characters are the same size on both monitors.