How much free space does defraggler need to defragment a hdd?
avidday04-
Hi and welcome to the forums!
The program itself is about a 3 MB download. As long as you have that much free space available (and if you don't, then you have more serious problems), the program should install and run.
As far as actually running, I can tell you that when an NTFS hard drive will start to give you problems when it fills up past 85%. That's not defrag program-related; it has to do with how the MFT handles the info on the drive.
Hope that helps! Let me know if I can help you out with anything else.
At least 15% is optimum then, tyvm for the info.