massive amount of HDD space being used by system

[TWR2005]

I have an old macbook pro (mid 2012) 15" I upgraded the HDD with a 1TB SSD and migrated the files from my old HDD to it, after cleaning up files deleting unimportant ones, removing games unplayable by the machine, moving documents and pictures to an external HDD i ...ran out of hard drive space. using the tools provided by the OS i found that all my hard drive space was used. doing quick math i deduced that the fresh operating system and the files migrated should be around 450gb. i managed to keep the machine running with 78gb of free space. and after several days managed to get it down to about only 85% full. I went over several migration videos and posts online and found nothing except that my system is using 650gb of space. before i do a clean install and go through the hell of reinstalling my Microsoft products i would like suggestions as to how to fix this issue. Thanks

 

[jorgk]

Do you have Time Machine running? (Check System Preferences, there it will be).
If so, it's probably the local files that add up to the quoted disk-use for the System.
Check this text for remedies.

 

[TWR2005]

no time machine. I looked for backups earlier as that's all i could figure, nothing. also i ran an app from the app store that tells me more about the hard drive and had it search for large files...it found none so its likely hidden and inaccessible to me in the system space