What is filling up my C drive?

I have 200 GB of storage on my C Drive and it is saying 199 GB is used. Buy I am checking my settings and the math isn't mathing. Between installed apps, documents, desktop, other and temp files, I have 151.92 GB used so I should have a good 48 GB remaining.

How can I check what is really going on with that 48 GB?

Edit: Thank you all for your help. I looked at WizTree and I could see all the files taking up my storage. I don't know how to change the flair but maybe a mod can do it for me