Mac storage basics · Checking your storage
How do I show file sizes under icons in Finder?
Short answer: In icon view, press Command-J and tick Show item info to see file sizes and folder item counts under icons.
In icon view, press Command-J to open View Options and tick Show item info. Finder then shows extra details under each icon — sizes for files and item counts for folders, and dimensions for images.
For sorting by size, List view with Calculate all sizes is more useful.