Is there any simple software/website/command to show the sensitivity of my mouse? I have a random cheap mouse which doesn't have really any software and I am looking to buy a better one with the same sensitivity.
Most basic mice have a 800 dpi more or less. When you buy your new mouse you can edit the dpi to your desired level. I don't think you ll ever find your basic mouse dpi, except for it is mentioned in the manufacturer's site/manual (if any)
Most mice without DPI changers are 800 DPI.
Mice that have DPI changing options can allow you to set specific settings in the software like 600, 800, 1000, 1500 etc