Having an issue with my Macbook Air (mid 2011). Using Get Info, my Macintosh HD shows 101 GB of free space. But when I use Disk Utility, it shows only 63 GB of free space. What is going on? I used Disk Utility to Verify Disk and it found problems, so I rebooted and performed Repair Disk successfully. Disk checks out OK but free space discrepancy is still there.
Message was edited by: Rocket88
Well, here is the answer: Time Machine Local Snapshots
Beginning with Lion, for laptop Macs only, Time Machine takes 2 snapshots each hour. The first one is stored locally on your laptop, the second is stored on your Time Machine designated backup drive. The first snapshot is limited in scope to only files you create, modify or delete. In my case, I recently downloaded a lot of camera files to my laptop while traveling, so my local backup contains over 38 GB of data. That is the difference in the "space available" calculations done by the Finder and by Disk Utility.
More info here:
My first clue was noticing in Time Machine that there are two backups for each hour, one minute apart. The "local" snapshot backup is marked with a gray color tick in the column on the far right side of the Time Machine window. The "full" backup is marked with a pink color tick.