How to Merge Partitions on Mac: A Detailed Guide

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When using a Mac, you might come across situations where you have multiple disk partitions, and they might not be serving your needs as efficiently as you'd like. Perhaps one partition is too small, while another has too much unused space. Merging partitions can be a great solution to simplify your storage setup and free up space. In this article, we'll walk you through how to merge partitions on Mac, using various methods such as macOS's built-in Disk Utility, Terminal commands, and third-party software.

Why Merge Partitions on Mac?

Before jumping into the technical details, let's first clarify what disk partitions are and why you might want to merge them in the first place.

A disk partition is essentially a separate, isolated section of your hard drive that the operating system treats as an individual disk. When you install macOS, the system typically divides your drive into several partitions, including the main system partition and others like Recovery or EFI. Some users also create additional partitions for organizing their data, backups, or for dual-booting different operating systems.

However, over time, you might realize that you have multiple partitions that no longer serve a useful purpose or that there is wasted space on certain partitions. Merging partitions helps free up space and simplifies your drive, consolidating data onto a single partition. It can be a great way to manage your storage and ensure you don't have unused space scattered across multiple partitions.

Important Warning: Merging partitions typically involves removing one or more partitions. This means there is always a risk of losing data. It's crucial to back up your data before proceeding with any partition operation.

🔗 Related link: how to back up Mac data with Time Machine or disk cloning software.

Prerequisites:

Before you begin, make sure you are ready to go through the partition merging process:

1. Check macOS Version: Different versions of macOS may have slight variations in tools and procedures. The methods mentioned in this guide work across macOS Mojave and later. Make sure your macOS is up to date to avoid potential compatibility issues with tools like Disk Utility.
2. Backup Your Data: The merging process can cause data loss if something goes wrong. Ensure that you've backed up all important data using Time Machine or another reliable backup solution before proceeding. You can also use an external hard drive to copy important files.
3. Free Space for Merging: For a smooth merging process, you need to ensure that at least one of your partitions has enough free space to accommodate the data from the partition you're merging. You may also need to delete the partition that will be merged, so make sure any important data has been moved to another location.

Step-by-Step Guide to Merging Partitions on Mac

1. Use Disk Utility to Merge Partitions on Mac

Disk Utility is macOS's built-in tool for managing disk partitions, and it offers an intuitive, user-friendly interface for merging partitions. Here's how to use it:

Step 1: Open Disk Utility: To access Disk Utility, follow these steps:

• Open Finder and go to the Applications folder.
• From there, navigate to Utilities and double-click Disk Utility.

Alternatively, you can search for "Disk Utility" using Spotlight (Command + Spacebar) and open it directly.

Step 2: Select the Partitions to Merge: Once Disk Utility is open, you'll see a list of all connected disks and partitions in the sidebar. Select the drive that contains the partitions you want to merge. You'll see all partitions listed under this drive.

Identify the partitions you wish to merge. You should have at least one partition with free space to accommodate the data from the other partition you are merging.

Step 3: Check Partition Format Compatibility: For Disk Utility to merge partitions, they must be formatted in a compatible file system, such as APFS (Apple File System) or HFS+ (Mac OS Extended). If the partitions are not compatible, you may need to reformat them, which will erase the data on the partitions.

Check the format of each partition by selecting it and looking at the information on the right side of the window.

Step 4: Delete the Partition to Merge: Once you've identified the partition to delete, click Partition tab. Then select the partition you want to delete and click the minus (-) button at the top of the Disk Utility window. This action will erase all data on the partition, so make sure you've backed up anything you need before doing this.

After deleting the partition, you should see the unused space appear as "Free Space."

Step 5: Resize the Remaining Partition: Next, select the partition you want to keep (the one that will absorb the data). Click the Partition button at the top of the Disk Utility window. A pie chart will appear showing the current partition setup.

To resize the partition, click the resize handle and drag it to fill the free space. Alternatively, you can manually enter the size by clicking on the partition and adjusting its size using the interface.

Once you're happy with the new partition size, click Apply to confirm the changes. Disk Utility will merge the partitions, and the free space will now be part of the selected partition.

2. Use Terminal to Merge Mac Partitions

For advanced users, Terminal provides a more granular level of control when merging partitions. Here's how to use the diskutil command to merge partitions:

Step 1: Open Terminal

To open Terminal: Go to Applications > Utilities > Terminal, or search for "Terminal" using Spotlight.

Step 2: Identify the Partitions

Type the following command into Terminal and press Enter:

diskutil list

This will display a list of all connected drives and their partitions. Note the identifier for the partitions you want to merge, typically listed as something like /dev/disk5s2, /dev/disk5s3.

Step 3: Delete the Partition

To delete the partition that you want to merge, use the following command:

sudo diskutil eraseVolume free none /dev/disk5s3

Replace /dev/disk5s3 with the identifier of the partition you wish to remove. This will erase the partition and leave it as unallocated space.

Step 4: Resize the Remaining Partition

Now that you have free space, you can resize the partition that will absorb the data. Use the following command:

sudo diskutil resizeVolume /dev/disk5s2 100%

Replace /dev/disk5s2 with the identifier of the partition you want to resize. This will resize the partition to take up 100% of the available space on the drive.

Once completed, the partitions will be merged, and the free space will be incorporated into the selected partition.

3. Merge Partitions with Third-party Software

While Disk Utility and Terminal are great tools for merging partitions, they may not always be the most flexible or powerful options, especially for users who require more control or encounter issues with built-in macOS tools. In such cases, third-party disk management tools like Paragon Hard Disk Manager or iPartition can help simplify the process.

Step 1: Download and Install a Third-Party Tool

Visit the website of the software you prefer, download it, and install it on your Mac. Follow the on-screen instructions to install the application.

Step 2: Select the Partitions to Merge

Open the disk management tool, and you should see a list of your partitions. Select the partitions you want to merge and follow the software's on-screen instructions. Most third-party tools provide a simple interface for merging partitions, making the process more straightforward than using Disk Utility or Terminal.

Step 3: Apply the Changes

Once you've selected the partitions to merge, the software will guide you through the process of deleting the unwanted partition and resizing the remaining partition to use the available space. Confirm the changes, and the software will automatically merge the partitions.

Common Issues and Troubleshooting: Can't Merge Partitions on Mac?

While merging partitions is a relatively straightforward process, there are some common issues users may encounter:

1. Partition Cannot Be Resized

If you cannot resize a partition in Disk Utility, it could be due to certain constraints on the partition format or layout. Try using a third-party tool for more flexibility, or consider reformatting the partition to a compatible format (make sure to back up your data before doing so).

2. Data Loss During Merge

To avoid data loss, always back up your files before merging partitions. If you accidentally erase data, there are data recovery tools available that can help retrieve lost files.

Follow the steps below to recover lost files after merging partitions on Mac:

Step 1. Download and install Donemax Data Recovery for Mac. It can completely recover lost files after merging or erasing partitions on Mac.

Step 2. Open Donemax Data Recovery for Mac, select the disk which contains the partitions to start data recovery.

Step 3. Click on Scan button to deeply scan the disk and find all deleted/erased/lost files.

Step 4. Once the scan is completed, you can preview all recoverable files. Then select the wanted files, click on Recover button to save them.

3. Disk Utility Won't Allow Merging

If Disk Utility fails to merge partitions, it could be due to a variety of reasons, including incompatible file formats or locked partitions. Try repairing the disk using the First Aid feature in Disk Utility, or use a third-party tool.

Conclusion

Merging partitions on your Mac can be a useful way to streamline your storage and reclaim wasted space. Whether you use Disk Utility, Terminal, or third-party software, the process is relatively simple as long as you take the necessary precautions to back up your data. Always ensure that you're working with compatible partition formats, and be mindful of the risk of data loss during the process.

Before you merging partitions on Mac, you can create a full bootable clone for your Mac by using disk cloning software.