Free Hard Drive Space Mac

Your Mac needs adequate hard drive space to operate normally. How full can a drive be before it's too full? There is no hard and fast rule that says “X” amount or “%” of free drive space is needed. A low amount of RAM requires more drive space for Virtual Memory’s swap files.
Problems from insufficient RAM and free hard disk space are discussed in this link
http://www.thexlab.com/faqs/lackofram.html
Here’s some general guidelines for minimum hard drive free space:
1. As a general rule, your available space should be 5GB as an absolute minimum as it generally requires that much free space to perform an Archive and Install of Mac OS X and still preserve some free space for VM swap files.
2. Some say that your hard drive should have at least 5% of it's capacity available for use. Still others say 10% to 15%. If you routinely process complex graphics and videos, even more space is required.
With your 19.7GB of free space, you should be OK. Usually it's best to not state a percentage, but state an amount of free space. There's a big difference in having 10% free space (20GB) on a 200GB hard drive compared 10% (4GB) to a 40GB hard drive.
Look at these links about freeing up more space.
Where did my disk space go?
http://www.macfixitforums.com/showflat.php?Cat=&Board=Forum38&Number=770243
Download & use WhatSize described in this link or Disk Inventory X @ http://www.derlien.com/
Freeing space on your Mac OS X startup disk
http://www.thexlab.com/faqs/freeingspace.html
Amazing Disappearing Drive Space
http://www.pinkmutant.com/articles/TigerMisc.html
Increase HD Free Space
http://macosx.com/forums/howto-faqs/275191-how-easily-increase-hd-free-space-lap top.html
How to free up my disk space
http://www.macmaps.com/diskfull.html
 Cheers, Tom 😉