Weird free spaces estimation

On my MacBook Pro Retina late 2014 running OS X Yosemite, there's something weird going on.

If i look at the storage tab in the "About my Mac" menu, I use only 67 gigabytes of storage but it says 151 gigabytes are used on apps alone.

Maybe this screenshot is a better explanation:

Is someone else experiencing this problem?

This information is calculated based on the Spotlight index. If your index is incorrect, this information can be incorrect too. Try reindexing your disk:

sudo mdutil -E /

sudo elevates the command to root to allow full control on the system. mdutil is the tool for controlling Spotlight. -E is the reindex option and / specifies the path to reindex. For more information on mdutil, see the man page.

It's possible that you have a corrupt index. The steps I'm going to show come from this Apple Support page. You must have permissions to add and remove items from the Privacy tab.

1. Click Apple menu > System Preferences > Spotlight
2. Click the Privacy tab
3. Drag the folder or disk that you want to index again to the list of locations that Spotlight is prevented from searching or click the Add (+) button to add it to the list. If the list is empty, add your main SSD, most commonly named Macintosh HD.
4. Click OK to confirm
5. Select the folder or disk you just added, then click the Remove (–) button to remove it from the list.
6. Quit System Preferences. Spotlight will reindex the contents of the folder or disk.

Once you've done all this, restart your Mac and check About This Mac -> Storage again. If the storage displays the same, then you know it's not because of a corrupt index.