Format
Formatting erases the selected volume. NTFS Kit keeps the existing partition map and rebuilds the filesystem; it is not a partition editor.
Options
| Filesystem | Tool | Best for | Limits |
|---|---|---|---|
| NTFS | mkntfs (NTFS-3G) | Disks used mainly on Windows; macOS write needs NTFS-3G | Requires macFUSE + NTFS-3G |
| exFAT | diskutil | Cross-platform disks and files over 4 GB | No journaling; choose safe ejection |
| FAT32 | diskutil | Maximum compatibility with older devices | Single file under 4 GB; 11-character label |
Preconditions
The format workflow refuses to continue unless all of these are true:
- The source is an external volume, not the boot disk or an internal system volume.
- The current volume name is shown and you type it exactly.
- You pass a final confirmation after reviewing the target, filesystem and label.
- The app unmounts the volume and rechecks device node/UUID before issuing the erase command.
- The volume identity still matches after unmounting; otherwise the command is not run.
Labels
- NTFS labels allow up to 32 Unicode characters.
- exFAT and FAT32 labels allow up to 11 ASCII letters, digits,
_or-, and are uppercased. - Invalid labels are rejected before any command reaches the system.
Recommended sequence
- Back up the volume. Formatting is not recoverable through this app.
- Select the external volume and confirm its device node and UUID.
- Choose NTFS, exFAT or FAT32 and enter the label.
- Review the confirmation dialog; type the current volume name exactly.
- Keep the disk connected until the command completes.
- Verify the new filesystem and mount it once before returning the disk to service.
Failure handling
| Situation | Behavior |
|---|---|
| Volume name mismatch | Stop before unmounting or erasing |
| Internal/boot volume selected | Refuse the operation |
| UUID/device changed after unmount | Stop and report identity mismatch |
| Driver missing for NTFS | Stop before unmounting |
| Erase command fails | Report the error code and log the command outcome; do not claim success |
After formatting
A new NTFS volume is still read-only on macOS until NTFS-3G is available. exFAT and FAT32 are readable and writable through macOS without extra drivers.