Mac storage basics · Checking your storage
Why do folder sizes in Finder look wrong or never update?
Short answer: Finder calculates and caches folder sizes in the background, so they lag after changes, and unreadable or online-only items skew them. Use Command-I to recalculate.
Finder calculates folder sizes in the background and caches them, so numbers can lag after big changes, and folders you can't read show partial sizes. Online-only cloud files count at their full size in some views even though they use almost no space.
Close and reopen the window, or select the folder and press Command-I to force a fresh calculation. For a measured, drill-down view, use a storage tool such as Storage Studio's What's Using Space.