Partitioning splits one physical drive into separate sections that macOS treats as independent disks. On a modern Mac you rarely need to do it — Apple’s APFS file system lets you add flexible volumes that share space automatically, which is better than a rigid partition for almost everyone. But there are still good reasons to reach for Disk Utility: running a second version of macOS, keeping a scratch area walled off, or prepping an external drive. Here is exactly how, and when to use a volume instead.
Volume vs. partition: pick the right one first
This is the decision that saves you the most grief:
- APFS Volume (recommended for most people). Volumes live inside one APFS container and share the free space on the drive. You do not carve out a fixed size, so a 256GB drive does not suddenly feel like two cramped 128GB drives. Add or delete a volume in seconds with no risk to your data.
- Partition (only when you truly need it). A partition reserves a fixed block of space that other partitions cannot touch. Use it when you need a second, isolated macOS install, a different file system (like a drive shared with a Windows PC), or a hard wall between two workloads. Resizing later is possible but slower and riskier than adjusting a volume.
Rule of thumb: if the words “but it needs its own fixed space” do not apply to you, add a volume, not a partition.
Before you start: back up
Resizing or partitioning a drive rewrites its map. It is usually safe, but “usually” is not “always.” Run a Time Machine backup first so a bad moment costs you minutes, not memories. On a Mac with very little free space, clear some room first — see our storage-full fix guide — because Disk Utility needs headroom to work.
How to add an APFS volume (the easy, safe way)
- Open Disk Utility (Applications → Utilities, or search it with Spotlight).
- In the sidebar, click your drive’s Container (usually “Container disk1” or “Macintosh HD”).
- Click the + button (“Add APFS Volume”) in the toolbar.
- Give it a name, leave the format as APFS, and click Add.
- Done. The new volume appears in Finder instantly and shares free space with your main drive.
To remove one later, select the volume and click the – button. That is the whole appeal: no repartitioning, no resizing math, no waiting.
How to partition a Mac drive (the fixed-size way)
Choose this only when you need an isolated, fixed section — for example a second macOS install or a differently formatted area.
- Open Disk Utility.
- Select the physical drive at the top of the sidebar (the device name, not a volume under it).
- Click Partition in the toolbar. If macOS suggests “Add Volume” instead, it is nudging you toward the safer option — click Partition only if you really need a fixed partition.
- Click + under the pie chart, then drag the divider or type an exact size.
- Name the new partition and pick a format: APFS for macOS use, Mac OS Extended (Journaled) for older-Mac compatibility, or ExFAT for a section you will share with Windows.
- Click Apply, review the summary, and confirm. This can take a few minutes.
Partitioning an external drive for Mac use
A brand-new external drive often ships formatted for Windows (NTFS), which macOS can read but not write to. To make it fully Mac-friendly, select the external drive in Disk Utility, click Erase, and choose APFS (for SSDs and modern macOS) or Mac OS Extended (for older Macs or Time Machine on a spinning drive). If the external drive is not appearing at all, work through our external drive not showing up guide first.
How to delete a partition and reclaim the space
- Open Disk Utility and select the physical drive.
- Click Partition.
- Select the partition you want to remove and click the – button.
- Click Apply. The freed space merges back into the neighboring partition.
Note: you cannot delete the partition you are currently booted from. If you set up a second macOS partition and want it gone, boot from your main drive first.
The honest part: when the real problem is a small drive
People often reach for partitioning to “organize” a Mac that simply ran out of room. Partitioning does not create space — it divides the space you already have. If your 256GB drive is always full, no partition scheme fixes that; a bigger drive does. It is worth reading 256GB vs 512GB before you spend an afternoon slicing up a drive that is too small to begin with.
If you decide an upgrade makes more sense, a refurbished Mac with a bigger SSD is the cheapest way there. Our Apple clearance lineup runs from a 256GB M1 MacBook Air at $450 up to roomier M2 and M3 configurations, each with a one-year warranty. And if you are wiping a drive to sell or hand down the old Mac, follow our factory reset guide first.
Related guides
- MacBook storage full? Here’s the fix
- External drive not showing up on Mac
- How to back up a Mac with Time Machine
- How to factory reset a MacBook
- All guides →
Frequently Asked Questions
Should I partition my Mac drive or add a volume?
For almost everyone, add an APFS volume. Volumes share free space automatically, take seconds to create or delete, and carry no resizing risk. Only use a fixed partition when you need an isolated section — a second macOS install, a different file system, or a drive shared with a Windows PC.
Will partitioning my Mac erase my data?
Adding an APFS volume does not touch your existing data. Creating or resizing a traditional partition usually preserves data too, but because it rewrites the drive map, always run a Time Machine backup first. Choosing Erase on a drive or volume will wipe that item.
How do I remove a partition on my Mac?
Open Disk Utility, select the physical drive, click Partition, select the partition, click the – button, and click Apply. The freed space merges back into the adjacent partition. You cannot delete the partition you are currently booted from.
Does partitioning slow down my Mac?
No. Partitioning does not make a Mac slower on its own. What slows a Mac is a nearly full drive — and partitioning shrinks the usable space in each section, which can make a small drive fill up faster. If speed is the issue, free up space or move to a larger SSD.
Can I partition a Mac to run Windows?
On Intel Macs you could partition and use Boot Camp. On Apple Silicon Macs (M1 and newer) Boot Camp does not exist — you run Windows through virtualization software like Parallels instead, which does not require a separate partition.
Do you buy Macs with drive or storage problems?
Yes. If a Mac has a failing SSD, a botched partition, or is simply too small for what you need, we buy it and can put credit toward a bigger refurbished model. Get a trade-in quote.