For Windows computers this is a very easy thing to do. Of course you can watch your screen as you boot up your computer and it may tell you there depending on how it’s configured. But once you are in Windows all you need to do is find the My Computer, Computer, or My PC icon depending on what version of Windows you are running. Many times it’s on your desktop and if it’s not then look under your Start menu or look under Control Panel for the System icon.
Once you find it simply right click on it and choose Properties. Then you will see a section that says Computer or System and it will show how much RAM you have installed in your computer.
Or you can open a command prompt and type in wmic MEMORYCHIP for more detailed information about your installed RAM.