Open Terminal or Command Prompt and connect to your Pi via SSH to get to the command line.
If you don't want to log into the Pi remotely, you can alternatively connect a USB keyboard and plug your Pi into a monitor or TV.
If you're running a system such as RetroPie, you'll need to press
F4 to exit to the command line.
Once on the command line, run the
You will now see your Pi's display resolution represented in terms of pixels and the overall geometry. For example, the RetroFlag GPi resolution is 320x240 (WxH):
mode "320x240" geometry 320 240 320 240 32 timings 0 0 0 0 0 0 0 rgba 8/16,8/8,8/0,8/24 endmode