How much free space do I have to leave on my partitions?

Endre555

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Jul 4, 2016
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So, I've partitioned & using my 1TB HDD this way:

C:
136GB total
60GB free
stuff on it:
Windows 10 (already installed)
softwares (most of them are installed but probabaly I will be installing some other smaller ones on it)


D:
794GB total
744GB free
stuff on it:
games (most of them will be installed in the future)
videos
pictures
music

My question is how much free space do I need to leave on each one of these drives in order to keep the performance at the current level, to allow defragmentaton to work correctly, etc.?