MacOS can act in mysterious ways, and it can be difficult from either the Finder or through > About This Mac > Storage view to figure out exactly what is eating up your disk storage. Especially on external drives, which the Storage display doesn’t break out into categories, or when System or Other seems to be occupying a truly enormous portion of your drive, and you can’t find a folder with that much data in it to examine.
Third-party apps can help. Several apps can graphically represent storage in detailed categories or by folders (or both). Some of those go further and can identify duplicated or unnecessary data you can remove, or can let you select files or folders you don’t need, and delete them directly within the app instead of navigating through the Finder.
DaisyDisk ($10 via the App Store or directly from the developer) offer a visualization that is quite pleasing and easy to use to navigate downwards into folders. If you find folders you want to delete, you can drag them to an icon in the lower-left corner. It doesn’t offer de-duplication and other more advanced features found in disk-cleaning software.
GrandPerspective (free download or $1.99 to support development via the App Store) visualizes storage in the form of a color-coded “heat map,” which uses relative size within a rectangle to indicate the percentage given files and folders occupy.
The gold standard used to be WhatSize ($30), which I reviewed back in 2015. It combines a graphic storage view with deduplication and other disk-cleaning features. Unfortunately, the developers stopped releasing updates following High Sierra. If you’re using an older version of macOS, it might be the best choice.
This Mac 911 article is in response to a question submitted by Macworld reader Woody.
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