Formatting or erasing a hard drive is often one of the first steps to setting up a new computer or repurposing an old one. Before formatting a hard drive, it’s important to back up any files you want to keep. Formatting will erase everything on the drive. Once backed up, formatting the drive will allow you to install a new operating system or partition the drive for different uses.
When to Format a Hard Drive
There are a few instances when you may need to format or erase your Mac’s hard drive:
- You are setting up a new Mac and need to format the hard drive before installing macOS.
- You want to erase all of the data on your Mac’s hard drive before selling or giving it away.
- Your Mac is running slowly and you want to wipe the drive and start fresh.
- You need to divide your hard drive into separate volumes or partitions.
Formatting your hard drive erases all of the data, so make sure to back up your files first.
How to Format a Hard Drive on Mac
Here are the steps to format your Mac hard drive:
- Back up your files. Use Time Machine or copy important files to an external hard drive or cloud storage.
- Restart your Mac and immediately press and hold Command + R to boot into Recovery Mode.
- Select Disk Utility from the utilities window.
- Click Continue.
- Select your hard drive from the left side pane.
- Click Erase at the top.
- Choose a format type – Mac OS Extended (Journaled) is recommended.
- Click Erase to confirm.
- Quit Disk Utility when done.
- You can now install a new OS or use Disk Utility to partition.
The steps above will format the entire hard drive. To erase just part of a drive or volume, select it from the left pane in Disk Utility before clicking Erase.
Choosing a Format Type
When erasing your hard drive, you’ll need to choose a format type. The recommended format for Mac hard drives is Mac OS Extended (Journaled). Here are a few format options:
- Mac OS Extended (Journaled) – The recommended format for Mac hard drives. Provides journaling which improves data integrity.
- APFS – The new Apple File System. Only compatible with macOS 10.13 or later.
- ExFAT – Compatible with both Mac and Windows. Lacks journaling.
- MS-DOS (FAT) – The standard Windows format. Avoid this unless you need Windows compatibility.
For most Mac users, Mac OS Extended (Journaled) is the best option. It is compatible with older and newer versions of macOS.
Partitioning the Drive
In addition to formatting an entire drive, you can also partition the drive into separate volumes. This allows you to have multiple sections that function as separate drives.
To partition a drive:
- Open Disk Utility
- Select the drive
- Click the Partition tab
- Click the + button to add partitions
- Choose the partition size and format
- Click Apply to partition the drive
Reasons to partition a drive:
- Keep your operating system separate from data
- Install multiple operating systems
- Create dedicated partitions for media, backups, etc.
When partitioning, make sure each section is formatted using the optimal format type.
Erasing External Drives
The steps to format an external drive like a USB flash drive or hard drive are the same as internal drives. External drives should also use the Mac OS Extended (Journaled) format.
Reasons to erase an external drive:
- To permanently delete all data before disposing of the drive
- To remove partitions or reformat the drive
- To reset the drive before performing backups
Make sure to back up any important data from the external drive before erasing. The process will overwrite all of the existing files.
Secure Erase Options
When formatting a drive, you can also choose to perform a secure erase. This overwrites the drive with random data to make the existing files unrecoverable.
To securely erase, choose one of these options in Disk Utility:
- Don’t erase data – A standard erase that simply removes file pointers. Data recovery is possible.
- Single-pass zero overwrite – Overwrites drive space with zeros. Provides basic protection.
- Multi-pass random overwrite – Repeatedly overwrites with random data. Maximum protection.
The more overwrite passes, the more securely data is erased. For maximum security, choose the 3-pass or 7-pass random overwrite option.
Time to Format a Hard Drive
The amount of time it takes to format a hard drive depends on the drive size and speed. Here are some general formatting times:
| Drive Size | Format Time |
| 500 GB HDD | 5-10 minutes |
| 1 TB HDD | 10-20 minutes |
| 2 TB HDD | 20-40 minutes |
| 500 GB SSD | 1-5 minutes |
| 1 TB SSD | 5-10 minutes |
| 2 TB SSD | 10-15 minutes |
SSDs can format significantly faster than traditional HDDs.
Tips When Formatting a Hard Drive
Follow these tips for a smooth formatting process:
- Always backup your data first.
- Use Mac OS Extended (Journaled) format for best performance.
- Zero out leftover data by selecting the secure erase option.
- Be patient – formatting a large drive can take over an hour.
- After formatting, install your operating system and restore data.
- Consider partitioning the drive if you need multiple sections.
Take the necessary precautions and formatting your Mac hard drive will be a breeze.
Common Partition Schemes
Here are some common partitioning schemes for a Mac hard drive:
- Single partition – The entire drive is one partition. Simple but no separation of OS and data.
- Two partitions – Separate OS and data partitions. Allows you to easily format OS partition.
- Three partitions – Add a recovery partition for troubleshooting. Lets you restore OS without internet.
- Four partitions – Extra data partition for backups or files like photos and videos.
The two or three partition scheme provides a good balance for most users. Just remember to make your data partition larger.
When Partitioning Goes Wrong
Partitioning carries a risk of drive corruption or lost data:
- Accidentally deleting or reformatting the wrong partition
- Power failure or disconnected drive during partitioning
- File system errors that damage partition structures
To avoid issues, backup your drive before partitioning and avoid interrupting the process. Be careful to not erase or overwrite important partitions.
If a partition becomes corrupted:
- Use Disk Utility First Aid to check and repair errors
- If repairs fail, you may need data recovery software
- In a worst case, the entire drive may need reformatting
Have backups and be cautious when repartitioning to avoid losing data.
When to Reformat vs Repartition
Should you reformat or repartition a hard drive for a new setup?
Reasons to reformat:
- Corrupted drive that needs a fresh start
- Changing file systems (PC to Mac or FAT32 to NTFS)
- Selling or donating the drive to someone else
Reasons to repartition:
- Adjusting the partition sizes on your current drive
- Adding or removing partitions to change your layout
- Keeping existing data while customizing partitions
Reformatting erases everything while repartitioning only modifies the structure. Choose based on your specific needs.
Conclusion
Formatting or erasing a hard drive is a common task for Mac users. Make sure to backup your data first, then boot into Recovery mode and use Disk Utility. Choose Mac OS Extended (Journaled) as the format and decide if you want to partition the drive. Allow plenty of time for the process to complete. With the right preparation, you can format your Mac’s hard drive smoothly.
