On Windows, right-click the desktop and select Display settings
Check the Display resolution field
On macOS, open System Settings and go to Displays
Check the Resolution setting
On Linux, open Settings and go to Displays
Check the listed screen resolution
Look in your monitor’s on-screen display menu
Check your graphics card control panel
Use a screen resolution checker website
Check your monitor’s manual or product specifications
Find the model number on the back of the monitor and search it online