Windows quota doesn't show real used space. How can we check exactly what user uses?

Could contemplate using FolderSize
I used it on a Windows 7 PC and it worked fine on that one for my requirements.
It adds a field in detail which shows directory size. So if a users H drive has a quota set, you can instantly see how much storage he or she is utilizing.

But TreeSize Pro is pretty good too as recommended by John. Just means you need to run reports manually if not mistaken (My last experience with it was years back really, I could be wrong, might have changed now)

Found a Microsoft Article on enabling folder size as well. It also explains impact on browsing due to this.

But for example set a quota limit in C: drive to 8GB and in Quota Entries it says user1 user 7GB. How can I know where user1 uses the space? How 7 GB of disk is splitted in C: drive?

Thanks guy for your suggestion. Finally the Storage Reports Management give me what I want because we can check by owner and it shows us all files used by users and their location.

Treesize Pro also can do that but " Storage Reports Management" works fine because we can select specific user and it's free.

Thanks for the update and I was happy to help.