Diff Your Mac Against Its Last Backup with tmutil compare

tmutil compare lists added, removed and modified files between the current disk and Time Machine backups.

macOSbackuptmutiltime-machineLow risk

Run `tmutil compare` to compare now against the latest backup, or `tmutil compare "path1" "path2"` to diff two backup dates.

01Command

Command

$ tmutil compare

02What it does

With no arguments, compare walks the live filesystem against the most recent backup and prints additions, removals, changes, plus the size and permission differences it found. With one argument it compares that backup against now, and with two it compares two backup points to each other — a quiet way to see what a day of work actually touched. Output can be long; pipe it through `tail` or a file when auditing. The same machinery decides what the next backup will copy.

03Risk

RiskLow risk

RequirementsRun without sudo for user files; add sudo to compare system-owned paths.

04Undo

✓No undo needed — this command does not change persistent state.

05Sources

tmutil — Time Machine utility (macOS man page)
SS64 · technical · 2026-09-17
Evidence: Documents tmutil compare with 0, 1 or 2 backup arguments, comparing the live filesystem against backups.

Last verified: 2026-09-18 · Category: System & Settings

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