How to Format a New External Hard Drive on Your Mac
Buying a new external hard drive is exciting — until you plug it into your Mac and realize it’s formatted for Windows.
Before you store files, photos, backups, or Time Machine data, formatting your external drive correctly is critical. This guide breaks down Apple Disk Utility in plain English and helps you choose the right format based on how you plan to use your drive.
🎓 What You’ll Learn
• Why new external hard drives should always be formatted first
• How to use Apple Disk Utility safely
• The differences between APFS, Mac OS Extended, FAT, and ExFAT
• When to use encryption
• What partition schemes mean (and when they matter)
• The difference between partitions and volumes
• How to check and repair disks
• A fun way to customize drive icons on macOS
💾 Why Formatting an External Drive Matters
Most external hard drives are shipped formatted for Windows compatibility, which limits performance and features on macOS.
Formatting allows your Mac to:
• Optimize performance
• Enable encryption
• Use modern file systems like APFS
• Prevent file-size and permission issues
Think of formatting as teaching your hard drive how to “speak Mac.”
🛠️ Understanding Disk Utility
Disk Utility is a built-in macOS tool used to:
• Format drives
• Create partitions and volumes
• Repair disk errors
• View detailed hardware information
You’ll find it in Applications → Utilities → Disk Utility.
🧩 File Formats Explained (Mac vs Windows)
🖥️ Mac-Only Formats
• APFS – Best for modern Macs and SSDs
• Mac OS Extended (Journaled) – Older Macs or legacy needs
🌍 Cross-Platform Formats
• MS-DOS (FAT) – Older compatibility, limited file sizes
• ExFAT – Best option for Mac + Windows file sharing
👉 My recommendation:
• Mac only → APFS
• Mac + Windows → ExFAT
• Time Machine (macOS Big Sur or newer) → APFS (macOS will enforce this)
Time Machine backups on modern macOS require APFS, and macOS will automatically format or convert the drive when you set it up.
🧱 Understanding Partition Schemes
Partition schemes define how a drive is structured at a hardware level.
• GUID Partition Map – Standard for modern Macs (recommended)
• Master Boot Record – Windows-focused setups
• Apple Partition Map – Legacy PowerPC Macs
For most users, GUID Partition Map is the correct choice.
🧠 Partitions vs Volumes
🧩 Understanding Volumes vs Partitions
Partitions split a drive into fixed sections that cannot dynamically resize without erasing data.
Volumes, especially with APFS, can grow and shrink dynamically while sharing space within a container — making them more flexible for modern macOS workflows.
📺 Check out my other blog page to learn: Mac Disk Utility Explained: How to Create Volumes and Partitions on External Drives
🧪 Disk Repair & Maintenance
The First Aid tool in Disk Utility checks drives for errors and can repair common file system issues. This is useful if:
• A drive won’t mount
• Files disappear
• Performance suddenly drops
⚡ SSD vs Traditional Hard Drives
SSD (Solid State Drives)
• Faster
• Silent
• More durable
• More expensive
Traditional HDD
• Slower
• Cheaper
• Mechanical (spinning disks)
For reliability and speed, SSDs are strongly recommended.
🎨 Fun Tip: Customize Your Drive Icons
macOS lets you customize the icon of:
• External drives
• Folders
• Volumes
This makes it easier to visually identify backups, archives, or project drives — and adds a little personality while you’re at it.
📺 Check out my other blog page to learn: How to Customize Folder and External Drive Icons on Your Mac