To move files from your Mac to an external hard drive, connect the drive, open it in Finder, and drag the files onto it. That copies them. Hold Command while you drag and Finder moves them instead, deleting the originals from your Mac once the copy finishes.
Moving is the step where people lose files, because the original is gone the moment Finder says it's done, and Finder doesn't check that what landed on the drive matches what left your Mac. If you're moving files to free up space, copy first, check the copy, then delete.
TL;DR: Drag files onto the external drive in Finder to copy them. Hold Command while dragging to move them (Finder deletes the originals). For anything you can't replace, copy, verify with rsync -anic or diff -rq, then delete. Move a Photos or Final Cut library only while the app is closed, and only to an APFS or Mac OS Extended drive. If Finder won't copy to the drive at all, it's usually formatted NTFS (read-only on Mac) or FAT32 (4GB file limit).
Step by Step: Copy Files to an External Drive
- Connect the drive. It appears in the Finder sidebar under Locations. If it doesn't, our drive not showing up guide walks through the fixes.
- Check there's room. Select the drive in Finder and press Command-I. Compare "Available" with the size of what you're copying (select the folders on your Mac and press Command-I again).
- Open two Finder windows. One on the folder you're moving from, one on the external drive. Command-N opens a new window.
- Drag the files or folders across. Finder shows a progress bar. Large video folders can take a while; copying to a spinning hard drive usually runs at 100-200 MB/s.
- Wait for the copy to finish before ejecting. Then eject the drive (right-click it in the sidebar, Eject) before unplugging.
Not sure whether part of the folder is already on the drive from an earlier copy? Add both to our free duplicate file finder first. It lists files that exist in both places, so you only copy what's missing.
Keyboard alternative: select files, press Command-C, open the drive, press Command-V to copy, or Command-Option-V to move.
Copy or Move: Which One Should You Use?
| You want to | Do this | What happens to the original |
|---|---|---|
| Keep a second copy on the drive | Drag (or Command-C, Command-V) | Stays on your Mac |
| Free up space on your Mac | Copy, verify, then delete | Deleted by you, after checking |
| Move quickly, files are replaceable | Command-drag (or Command-Option-V) | Deleted by Finder right after the copy |
Command-drag is fine for downloads you could fetch again. For client footage, family photos, or anything that exists only on your Mac, copy and check first. After a move, the external drive holds the only copy, so the next step is getting a second copy of it somewhere else. Backing up an external drive covers that.
Check the Copy Before You Delete Anything
Finder decides a copy succeeded if no error came up. It doesn't compare the contents of the files on both sides.
I tested how much a quick check misses on macOS 15.5. I copied a folder of video files, then changed one byte inside one copy, keeping its size and modification date. A size-and-date check (rsync -ani) reported nothing wrong. Two content checks caught it.
Open Terminal and run either of these, replacing the paths with your folder and the drive:
diff -rq ~/Movies/Wedding-2026 /Volumes/Archive/Wedding-2026
rsync -anic ~/Movies/Wedding-2026/ /Volumes/Archive/Wedding-2026/
diff -rq prints a line for every file that differs or is missing on one side. rsync -anic lists files whose contents differ (lines starting with >f) and changes nothing, because -n makes it a dry run. No file lines in either output means the copy matches. Both read every byte on both sides, so a 500GB folder takes a while.
Once it's clean, delete the originals and empty the Trash.
How to Move Your Photos Library to an External Drive
The Photos library is a single package file, usually in your Pictures folder, and it's often the biggest thing on a Mac. Apple supports moving it:
- Quit Photos.
- In Finder, open Pictures and drag Photos Library.photoslibrary to the external drive. The drive needs to be APFS or Mac OS Extended, not exFAT, and not your Time Machine drive.
- Hold Option while you open Photos, choose Other Library, and select the library on the external drive.
- If you use iCloud Photos, go to Photos → Settings → General and click Use as System Photo Library.
- Open a few albums and play a couple of videos from the moved library. Once it works, delete the old library from Pictures.
From then on, connect the drive before opening Photos. If the drive is missing, Photos creates a new, empty library in Pictures, which looks alarming but leaves your real library untouched. Apple also warns against keeping the library on an SD card, a USB flash drive, or a network share. Apple's own steps are in Move your Photos library to save space.
Moving Final Cut Pro, Lightroom, and Other App Libraries
App libraries hold references between files, so the rule is the same for all of them: close the app, then move.
- Final Cut Pro: quit Final Cut, drag the
.fcpbundlelibrary to the external drive in Finder, then open it from there (File → Open Library). Final Cut libraries need an APFS or Mac OS Extended drive. - Lightroom Classic: move photo folders from inside Lightroom's Folders panel, not in Finder, so the catalog follows them. The full process, including moving the catalog itself, is in our Lightroom external hard drive guide.
- iCloud Drive with Optimize Mac Storage on: some files in iCloud Drive are placeholders that only download when opened. Right-click the folder and choose Download Now before copying, so you're moving full files and not waiting on downloads mid-copy.
Why Can't I Move Files to My External Hard Drive?
Three causes cover most "can't copy" problems:
- The drive is NTFS. macOS reads NTFS drives (the Windows default) but doesn't write to them. Finder shows the files but won't let you add anything. Check with Command-I on the drive: "Format" says NTFS. Copy the data off, then reformat as exFAT (Mac and PC) or APFS (Mac only).
- The drive is FAT32 and the file is over 4GB. FAT32 can't store files larger than 4GB, which rules out most video files. Same fix: reformat as exFAT or APFS.
- Permissions or a locked drive. If Command-I shows "You can only read" at the bottom, click the lock, and either tick "Ignore ownership on this volume" or give your user Read & Write.
The Faster Way, If You Do This Every Month
Tusk is a Mac app that automatically backs up your project folders to multiple locations and tracks where every file lives — even when your drives aren't connected.
If you regularly move finished projects off your Mac to make room, Tusk does the copy, check, delete sequence for you. You add a project folder and its backup destinations (one or more external drives, and cloud if you want it). Tusk copies each file and checks its BLAKE3 hash on arrival. When you click Delete local, it first confirms every file is on every connected destination and refuses to delete anything that isn't.
Tusk keeps a record of where each file went, so six months later you can see which drive holds the project without plugging every drive in. And Restore everything copies the project back to your Mac from the best available copy when a client asks for changes. Tusk is Mac only and currently restores a whole project or folder at once, not single files.
FAQ
Connect the drive, open it in Finder, and drag the files onto it to copy them. To move them instead (deleting the originals from your Mac), hold Command while dragging, or select the files, press Command-C, open the drive, and press Command-Option-V. For files you can't replace, copy first, check the copy, then delete the originals.
It copies them. Dragging between two different drives in Finder always copies, so the originals stay on your Mac. Hold Command while dragging to move them. Dragging within the same drive moves files by default.
Compare the contents, not just the file list. In Terminal, diff -rq followed by the original folder and the copy prints every file that differs or is missing. rsync -anic with both folder paths does the same as a dry run. A check that only compares file size and date can miss a damaged file; in our test on macOS 15.5 it missed a one-byte change entirely.
Yes. Quit Photos, drag Photos Library.photoslibrary from your Pictures folder to an APFS or Mac OS Extended drive, then hold Option while opening Photos and choose the library on the drive. If you use iCloud Photos, set it as the System Photo Library in Photos Settings. Delete the old library only after the moved one opens and plays correctly.
Usually because the drive is formatted NTFS, which macOS can read but not write, or FAT32, which can't hold files over 4GB. Select the drive in Finder and press Command-I to see its format. Copy anything you need off it, then reformat it as exFAT (for Mac and PC) or APFS (Mac only) in Disk Utility. Less often, the drive's permissions are set to read only, which you can change in the same Command-I window.
Only after you've checked the copy, and ideally only once the files exist in two places. After you delete the originals, the external drive is the only copy, and external drives fail, get dropped, and get lost. Make a second copy on another drive or in the cloud before deleting anything you can't replace.