Mac storage basics · Time Machine basics
Will turning off Time Machine free up space on my Mac?
Short answer: Somewhat — Time Machine stops making local snapshots and their space is released as they expire — but you lose backups. Release snapshots when needed instead.
A little, over time: with Time Machine off it stops making its hourly local snapshots, so the space they hold is released as they expire. But you also stop backing up — a poor trade for some temporary space.
A better approach is to keep Time Machine on and release snapshots when you need room, or exclude large, rebuildable folders from backups.