Mac storage basics · Memory, swap and speed

How do I see which app is writing the most to my disk?

Q: How do I see which app is writing the most to my disk?

Open Activity Monitor, click the Disk tab and sort by Bytes Written. The top entries are writing the most since they started. A graph at the bottom shows overall reads and writes. Heavy writing from backup, sync, indexing and photo-analysis processes is normal for a while after big changes. An ordinary app writing continuously may be filling caches or logs — check its settings or update it.

Short answer: Open Activity Monitor's Disk tab and sort by Bytes Written. Backup, sync and indexing processes write a lot after big changes; constant writing by an ordinary app is worth checking.

Open Activity Monitor, click the Disk tab and sort by Bytes Written. The top entries are writing the most since they started. A graph at the bottom shows overall reads and writes.

Heavy writing from backup, sync, indexing and photo-analysis processes is normal for a while after big changes. An ordinary app writing continuously may be filling caches or logs — check its settings or update it.

Last reviewed October 1, 2026

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How do I see which app is writing the most to my disk?

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