How to Resize or Merge Partitions on Mac Without Losing Data: Step-by-Step

August 14, 2025 by Andrew Smith

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So, you’ve run out of space on your Mac, and you’re wondering—can I really resize or merge partitions without losing all my stuff? The answer is a big, happy YES! It might sound technical, but with a little patience (and this guide), you’ll be a partition pro in no time.

Let’s keep it fun, simple, and most importantly, safe.

🎉 What Are Partitions, Anyway?

Imagine your Mac’s hard drive like a pizza. 🍕 Each slice is a partition—separate, but all part of the same delicious disk. You might have partitions for macOS, data, Time Machine backups, or even Windows if you’re using Boot Camp.

But sometimes, one slice gets too tiny. That’s when you need to resize or merge partitions.

🛠️ Before You Touch a Thing

Back. It. Up. Always. Every. Time.

Before messing with partitions, backup your data. Even if it’s totally possible to resize without losing anything, things can go sideways.

  • Use Time Machine (macOS’s built-in tool)
  • Or clone your disk using tools like Carbon Copy Cloner or SuperDuper

Safety first = stress less.

🖥️ Use Disk Utility Like a Boss

Disk Utility is your go-to app for management magic. Here’s how to access it:

  1. Go to Applications > Utilities
  2. Open Disk Utility

To Resize a Partition:

  1. Select the disk (not the volume) from the left panel
  2. Click Partition in the top toolbar
  3. A pie chart will show your current partitions
  4. Click and drag the divider between partitions to change sizes
  5. Click Apply

Note: You can only increase size if there’s free space beside the partition you want to grow.

To Merge Partitions:

Two rules:

  • They must be on the same physical drive
  • One should be empty (or okay to delete)
  1. Select the empty partition
  2. Click the – (minus) button to delete it
  3. Now select the main partition you want to grow
  4. Drag to fill the newly vacant space
  5. Click Apply

And ta-da! The extra space is now yours 🌟

🤓 Using Terminal (For Brave Nerds Only)

If you’re feeling fancy, Terminal lets you do more advanced stuff using diskutil. Be VERY careful though.

Example to check your disks:

diskutil list

To resize a volume:

diskutil resizeVolume disk2s1 200G

This resizes a volume to 200 GB. You must know the exact name (like disk2s1), so tread lightly!

🧼 Some Friendly Tips

  • Keep at least 10-20% free space on your main partition. Your Mac loves breathing room.
  • Name your partitions wisely. “Stuff” isn’t very helpful.
  • If something fails, don’t panic. Boot into Recovery Mode and repair disk using First Aid.

🔄Can’t Resize? Try This First

Sometimes Disk Utility will refuse to resize. Here’s what to try:

  1. Run First Aid in Disk Utility
  2. Boot into macOS Recovery (restart and hold Command + R)
  3. Then try resizing again

If nothing works, consider third-party tools like:

  • iPartition
  • Paragon Hard Disk Manager

These offer more options but always double-check compatibility with your macOS version.

🙌 You Did It!

And guess what? You didn’t lose a single file. Magic? Nope. Just smart steps. Resizing and merging partitions doesn’t have to be scary. Thanks to Disk Utility and a little knowledge, your Mac is now a clutter-free zone with space to spare.

So go ahead—download that game, store more cat pics, or start your next epic video project. You’ve earned it!

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