Format an external drive as APFS if it will only ever be used with Macs. Format it as exFAT if it also needs to work with Windows PCs, cameras, TVs, or game consoles. APFS is safer against sudden disconnects, supports Time Machine, snapshots, and encryption, and makes copies on the same drive instantly. exFAT gives up all of that in exchange for working almost everywhere.
The choice has a consequence people often find out too late: Time Machine can't back up an exFAT drive, and can't use one as a backup disk either.
TL;DR: APFS: Mac only, journaled-style crash protection via copy-on-write, snapshots, encryption, required for Time Machine. exFAT: reads and writes on Mac and Windows (and most cameras and TVs), no journaling, so an unsafe eject can corrupt it, and Time Machine can't back it up or use it. Mac OS Extended (HFS+) is only for Macs older than macOS 10.13. FAT32 can't hold files over 4GB. NTFS is read-only on Mac.
APFS vs exFAT vs the Other Formats
| Format | Mac | Windows | Max file size | Survives sudden disconnects | Time Machine | Use it for |
|---|---|---|---|---|---|---|
| APFS | Read/write (macOS 10.13+) | No (needs third-party software) | Effectively unlimited | Better (copy-on-write metadata, checksummed) | Yes | Any drive that stays with Macs |
| exFAT | Read/write | Read/write | Effectively unlimited | Worse (no journal) | No | Drives shared with PCs, cameras, TVs |
| Mac OS Extended (HFS+) | Read/write | No | Effectively unlimited | Good (journaled) | Older backups only | Macs older than High Sierra |
| FAT32 (MS-DOS) | Read/write | Read/write | 4GB | Worse | No | Small USB sticks, old devices |
| NTFS | Read only | Read/write | Effectively unlimited | Good on Windows | No | Windows-only drives |
When to Use APFS
Use APFS for any drive that only connects to Macs: backup drives, archive drives, editing SSDs, Time Machine disks.
- It handles unsafe ejects better. APFS writes changes to new locations instead of overwriting in place, and it checksums its own metadata, so a disconnect mid-write is much less likely to damage the volume. It doesn't checksum file contents, though; more on that in our bit rot guide.
- Time Machine needs it. New Time Machine disks have been APFS since macOS 11 Big Sur, and Time Machine only backs up source drives formatted APFS or Mac OS Extended.
- Copies on the same drive are instant. Duplicating a 50GB file on an APFS drive creates a clone that takes no extra space until one copy changes.
- Snapshots and encryption. APFS supports both, and Disk Utility offers "APFS (Encrypted)" when you format.
- Several volumes can share one drive's space without fixed partition sizes.
Apple designed APFS for SSDs, and it's the default for spinning hard drives too on current macOS. On a hard drive that's very full and heavily fragmented, APFS can feel slower than HFS+ did, but for backup and archive drives that rarely matters.
When to Use exFAT
Use exFAT when a drive has to move between a Mac and anything else:
- A drive you share with a Windows PC, at home or with a client
- Camera media (SD cards over 32GB are formatted exFAT by most cameras, and you should format cards in the camera, not on the Mac)
- A drive for a TV, game console, or car
The cost is real. exFAT has no journal, so pulling the cable during a write, or a Mac going to sleep with the drive mounted, can leave the volume needing repair. macOS runs a check (fsck_exfat) when it mounts a "dirty" exFAT drive, which can make the drive take a long time to appear. Our drive not showing up guide covers that case. Time Machine also lists exFAT drives in its exclusions with no way to remove them, so you need another way to back up an exFAT drive.
What About Mac OS Extended (Journaled)?
Mac OS Extended (also called HFS+) was the Mac format before APFS. Choose it only if the drive needs to work with Macs running macOS 10.12 Sierra or older, which can't read APFS. Older Time Machine disks formatted HFS+ keep working, but new ones use APFS.
How to Format an External Drive on Mac
Formatting erases everything on the drive. Copy anything you need off it first.
In Disk Utility:
- Open Disk Utility (Applications → Utilities).
- Choose View → Show All Devices, then select the drive itself (the top line, not the indented volume under it).
- Click Erase.
- Enter a name, choose the format (APFS or ExFAT), and choose GUID Partition Map as the scheme.
- Click Erase.
Selecting the whole drive matters. Erasing only the volume keeps the old partition map, which is what causes "can't format as APFS" errors on drives that came formatted for Windows.
In Terminal: first find the drive's identifier:
diskutil list external
Then erase it (here disk4; double-check yours, this deletes everything on it):
diskutil eraseDisk APFS Archive GPT /dev/disk4
For exFAT, replace APFS with ExFAT. To see every format your Mac can create, run diskutil listFilesystems. On macOS 15.5 the list includes APFS, APFS (Case-sensitive), ExFAT, MS-DOS (FAT), FAT12/16/32, and four variants of Mac OS Extended. NTFS isn't on it.
Can You Convert exFAT to APFS Without Losing Data?
No. Changing between exFAT and APFS means erasing the drive. Copy everything to another drive, check the copy (our guide to moving files to an external drive shows how to compare both sides), reformat, and copy it back. The one in-place conversion macOS offers is from Mac OS Extended to APFS: in Disk Utility, select the HFS+ volume and choose Edit → Convert to APFS. Back up first anyway.
FAQ
APFS if the drive will only be used with Macs, including as a Time Machine disk or a backup drive. exFAT if it also needs to work with Windows, cameras, or TVs. APFS handles sudden disconnects better and supports snapshots, encryption, and Time Machine; exFAT trades those for compatibility.
exFAT. Both macOS and Windows read and write it without extra software, and it has no practical file size limit, unlike FAT32's 4GB cap. Eject it properly every time, because exFAT has no journal and an unsafe disconnect can corrupt it.
No. Time Machine can't use an exFAT drive as a backup disk, and it can't back up an exFAT drive as a source either; such drives appear in the exclusion list with the remove button grayed out. Format a Time Machine disk as APFS.
APFS works on hard drives and is the default for them on current macOS, including Time Machine disks since Big Sur. It was designed with SSDs in mind, so a very full, heavily fragmented hard drive can feel slower than it did with Mac OS Extended, but that rarely matters for backup and archive drives.
Open Disk Utility, choose View, Show All Devices, select the drive itself (not the volume), click Erase, pick APFS and GUID Partition Map, and click Erase. In Terminal: diskutil eraseDisk APFS DriveName GPT /dev/diskN, after confirming the disk number with diskutil list external. Both erase everything on the drive.