Comparisons & alternatives · macOS's own storage tools
Can't Activity Monitor show me what's filling my disk?
Short answer: Activity Monitor shows which processes are reading and writing now. Storage Studio's 'Where did my space go?' shows how free space changed over a period, what grew, and which app was responsible when it can tell.
Partly. Activity Monitor's Disk tab shows how much each running process is reading and writing right now and since it started — useful for spotting a busy app, but it doesn't tell you how much space was used up, where it went, or what happened while you weren't looking.
Storage Studio answers the space question directly:
- it watches free space over time and can break down any period you pick — what grew, what was freed, and what it couldn't account for;
- it names the app responsible when it can identify one;
- it measures temporary and cache areas and attributes what's there to the app that put it there.
Use Activity Monitor to see who's busy now, and Where did my space go? (More •••) to see where the room went. See What's Using Space.