You need to wipe a USB flash drive, external hard drive, or external SSD, fix a corrupted format, or make the drive work with another device. This guide is for external and secondary drives, not formatting the computer main internal system drive.
Does This Affect You?
Formatting erases the drive and creates a new file system, which controls how files are stored and which devices can read or write them. It is useful for starting fresh, changing compatibility between Windows and Mac, or preparing a drive for cameras, TVs, consoles, and other devices.
Formatting permanently erases the selected drive through normal use. Back up anything you need before continuing and double-check the drive name and size before clicking Format or Erase. We provide no warranty; proceed at your own risk.
Format a Drive on Windows
Windows can format from File Explorer for most external drives.
- Plug in the drive and open File Explorer.
- Click This PC, right-click the target drive, and choose Format.
- Choose a file system. Use exFAT for drives shared between Windows and Mac with large files, NTFS for Windows-only drives, or FAT32 for older devices that need maximum compatibility but cannot store individual files larger than 4GB.
- Leave Allocation unit size at the default unless you have a specific reason to change it.
- Enter a Volume label if you want a friendly drive name.
- Leave Quick Format checked for normal use. Uncheck it only when you need a thorough scan, which can take hours.
- Click Start, confirm the erase warning, and wait for completion.
Format a Drive on Mac
macOS uses Disk Utility for this job.
- Connect the drive and open Disk Utility from Spotlight or Applications > Utilities.
- Select the physical drive or the volume you want to erase in the sidebar. Select the top-level drive if you want to erase the whole device.
- Click Erase.
- Choose a format. Use exFAT for Windows and Mac sharing, APFS for modern Mac-only SSD use, or Mac OS Extended (Journaled) for older Mac-only compatibility.
- For Scheme, use GUID Partition Map on modern Macs unless a device manual tells you otherwise.
- Click Erase, confirm, and wait for Disk Utility to finish.
For most external drives that move between Windows and Mac, exFAT is the best default because both systems can read and write it and it does not have FAT32 4GB file limits. Use NTFS for Windows-only drives that need Windows permissions and features. Use APFS for modern Mac-only SSDs.
If formatting fails or the drive is write-protected, the drive may have a hardware fault or a stuck partition state. On Windows, DiskPart with the clean command can reset some stubborn drives, but it is powerful and erases the selected disk completely, so identify the disk carefully.
Sources
- Microsoft Support – Format a hard disk in Windows (2025)
- Apple Support – Format a disk for Mac (2025)
- Western Digital – Choosing between exFAT, NTFS, and FAT32 (2024)