Messages attachments taking up space on a Mac
· 7 min read
If Messages is taking up a surprising amount of storage on your Mac, the space is almost always attachments: photos, videos, voice notes and files that arrived in conversations, sometimes years ago. The safe way to clear them is from System Settings, General, Storage, where the Messages row lets you review and delete large attachments individually. Before you delete anything, check whether Messages in iCloud is on, because with it on a deletion on the Mac also removes the item from your other devices.
Here is what is actually using the space and how to reduce it without breaking your message history.
Where the space goes
Messages keeps its data in your user Library, in ~/Library/Messages. Inside are two things that matter:
- The database holding the text of every conversation. It is rarely large, even after years.
- The Attachments folder holding every photo, video, audio message, sticker and document ever sent or received on this Mac, stored as ordinary files in a nest of subfolders.
Almost all of the size is in Attachments. A group chat that shares videos, or a family thread full of photos, can reach many gigabytes on its own. The Mac keeps these indefinitely unless you have told it otherwise, so a Mac that has been signed in for several years can carry a long tail of media nobody will look at again.
To see the total, open System Settings, General, Storage and wait for the bars to finish calculating. Messages gets its own row with a size next to it.
Before you delete: check Messages in iCloud
This single setting decides whether a cleanup on the Mac is local or global.
Open Messages, choose Messages, Settings, then the iMessage tab. If “Enable Messages in iCloud” is ticked, your conversations and attachments are synced across every device signed in to the same Apple Account. Deleting an attachment or a conversation on the Mac deletes it on your iPhone and iPad as well.
That is often exactly what you want, but not always. If there are photos in a thread you want to keep, save them to Photos or to a folder first: open the conversation, click the info button, and use the Photos or Files section to find and save them.
If Messages in iCloud is off, each device keeps its own copy, and deleting on the Mac affects only the Mac.
Method 1: review large attachments in Storage settings
This is the cleanest route because macOS removes the attachment and updates the conversation together.
- Open System Settings, General, Storage.
- Find the Messages row and click the info button next to it.
- You get a list of attachments with their sizes. Sort by size if the list is not already in that order.
- Select the ones you do not need (Command-click to pick several) and click Delete.
Start at the top of the list. A handful of long videos usually account for more space than hundreds of photos. The conversation stays; the attachment is replaced with a note that it was deleted.
Method 2: stop keeping everything forever
In Messages, open Settings, General, and look at Keep messages. The default is Forever. Changing it to 1 Year or 30 Days makes the Mac delete older messages and their attachments automatically, now and from then on.
This is effective and blunt. It removes the text of old conversations too, not just the media, and with Messages in iCloud on it applies across your devices. Choose it only if you genuinely do not need an archive of old conversations. If you do, stay with Method 1 and prune by hand once or twice a year.
Method 3: delete whole conversations
For threads that were mostly media and have no lasting value, such as a one-off group chat for an event, deleting the conversation removes its attachments with it. In Messages, right-click the conversation in the sidebar and choose Delete. Recently deleted conversations can be recovered for a period from View, Recently Deleted, which also means the space is not released immediately.
What not to do
It is tempting to open ~/Library/Messages/Attachments in Finder and drag the whole folder to the Trash. Do not.
The database still expects those files. Conversations then show blank or broken attachments, Messages may try to download items again from iCloud, and you can end up with the space coming back while the history is damaged. Deleting through the Messages app or Storage settings keeps the two in step.
Similarly, do not delete the chat.db files. That is your message history.
If you want to look inside the folder to understand where the space is, that is fine; looking changes nothing. Use Go, Go to Folder in Finder and paste ~/Library/Messages. Terminal may be refused access to this folder unless it has Full Disk Access, which is macOS protecting your messages, not an error.
When Messages is only part of the picture
Messages is often one of several things quietly filling a drive. Photos, Mail attachments and old iPhone backups follow the same pattern: media that arrived once and never left. Mail is taking up storage on a Mac and the Photos library is taking up space cover the other two, and the Mac says storage is full but the folders do not add up helps when the numbers in Storage settings do not match what you can find.
If you want the whole picture in one place, Crumb is a menu bar disk cleaner whose read-only audit covers the whole Mac, including the System Data breakdown, local snapshots and iOS backups. Its Ask Crumb feature is useful for folders like this one: point it at an item and it explains what it is, whether it regenerates, and what breaks if it is gone, then proposes a plan. Nothing is deleted until you approve it. For Messages specifically, the built-in Storage review above is the right tool, because it keeps conversations and attachments in step.
Questions
Will deleting attachments on my Mac delete them on my iPhone? Only if Messages in iCloud is on. Check Messages, Settings, iMessage first, and save anything you want to keep before deleting.
Why did the space not come back right away? Deleted conversations sit in Recently Deleted for a while, and the Storage figure can take a few minutes to recalculate. Empty Recently Deleted in Messages if you need the space now.
Can I move Messages attachments to an external drive? Not in a supported way. Messages expects its data in your Library folder. Save the photos and videos you care about to Photos or a folder on the external drive, then delete them from Messages.
Is it safe to turn off Messages in iCloud to save space? It changes how conversations sync between devices, not how much this Mac keeps, so it is not a storage fix. The Mac still holds its own copy of the history and attachments. Use Keep messages or the Storage review instead.