Switch any Finder window to List view and look at the Size column. Files show their size, but every folder shows “–” instead of a number. It’s not a bug — macOS hides folder sizes on purpose, because calculating them means scanning every file inside. The good news: enabling folder sizes takes four quick steps, and one extra click makes the setting permanent.
Show folder sizes in Finder step by step
- Open a folder in Finder and switch to List view. Click View → as List in the menu bar, or press Command + 2.
- Open View Options. In the menu bar, choose View → Show View Options, or press Command + J.
- Tick “Calculate all sizes”. In the View Options window, check the Calculate all sizes box. Finder immediately starts computing sizes for the folders in the current window.
- Click “Use as Defaults”. Still in View Options, click Use as Defaults at the bottom — this applies the setting to every folder, not just the one you have open.
- Give Finder a moment. The first time, Finder needs to scan folders containing lots of files, so sizes may take a little while to appear.
If it still doesn’t work
If folders still show “–“, close and reopen the Finder window — and be patient with very large folders, where the first calculation can take several minutes. If “Calculate all sizes” won’t stay on, make sure you clicked Use as Defaults; without it, the option only applies to the current folder. For the official documentation, see Apple Support’s Finder user guide; MacRumors also rounds up handy macOS Finder tips.
More Finder tricks: learn how to change a folder’s color or add an emoji in macOS 26 and quickly open the installed apps list in macOS 26.
Frequently asked questions
Why does Finder hide folder sizes by default?
Because calculating a folder’s size requires scanning every file inside it. On large drives that scanning slows down browsing, so Apple leaves the option off to keep Finder fast until you ask for it.
Will enabling this slow down my Mac?
You may notice a brief delay the first time Finder computes sizes for folders packed with files. After that, sizes are cached and browsing feels normal.
Conclusion
Folder sizes are one checkbox away: open any folder in List view, press Command + J, tick “Calculate all sizes”, and hit “Use as Defaults”. From then on, Finder shows you exactly how much space every folder takes — no guessing, no third-party tools.
