How to share an external hard drive between Mac and Windows

Tyler Lacoma

Compatibility issues between Microsoft’s Windows and Apple’s MacOS have diminished sharply over the years, but that doesn’t mean those issues have completely disappeared. Today, if you buy a new external hard drive, you may notice that working between the two is an often demoralizing task.

But it doesn’t need to be.

Fortunately, there is a solution. You can “partition” your hard drive, or divide it into different sections with different rules and functions. In this case, you can partition your drive so that part of it works properly with MacOS and part of it works properly with Windows, avoiding the issues that can crop up. Both computers have the necessary tools to help you partition a new drive once you have it connected.

External hard drive

It’s a split, niche scenario

A quick Google search may lead you to believe you’re on the right path by formatting the entire drive with Extensible File Allocation Table, or exFAT. It’s a simpler, universal method if every file you store is less than 4GB in size. However, this format doesn’t support larger files, which can be problematic for transferring 4K videos and so on between Macs and Windows 10 PCs.

Meanwhile, the NTFS system used by Windows 10 supports large files, but this format can’t be read natively by MacOS. That puts you in a peculiar pickle, limiting any shared file between the two platforms at 4GB or smaller. If you want to save larger files, you’ll need to create a second, dedicated space using a format optimized for MacOS (Extended) or Windows 10 (NTFS).

That said, our guide splits the external drive in half: One primary section capable of storing files larger than 4GB, and a secondary section capable of sharing files between MacOS and Windows 10. It’s not the ideal solution — we get it — but it works nonetheless.

Before digging in, select a primary format you’ll use the most: MacOS Extended if you primarily use Mac with a secondary exFAT partition, or NTFS if you mainly use Windows 10 with a secondary exFAT partition.

Finally, formatting deletes all data stored on the drive. Make sure you back up anything important before beginning the formatting process. We have guides for Windows and MacOS in case you need a helping hand.

Partition the drive on Windows 10

Bill Roberson/Digital Trends

We have a full guide on how to complete the process from Windows 10 here. But let’s go through the important steps you need to know to quickly partition the drive while working on Windows. On a PC, the process is less straightforward than what you see on a Mac, but it’s now easier than ever.

Step 1: Right-click on the Start button and select Disk Management on the pop-up menu.

Windows 10 Disk Management

Your PC’s primary boot drive (C:) hosting Windows and other programs appears as Disk 1. If your PC has a secondary “data” drive (D:), Disk Management assigns it as Disk 0. Windows 10 typically lists an external drive as Disk 2 along with the next successive alphabetic label if you don’t have any other internal disk-based storage. Windows 10 lists optical drives differently.

Typically, external drives are formatted out of the box. However, you may encounter a “Not Initialized” error when connecting the device to your PC. That means it’s not formatted correctly to work with Windows. Even more, it won’t have an assigned drive letter in File Explorer (This PC), and may not even have allocated space for saving data.

Windows 10 Initialize Disk

If you see an Initialize Disk pop-up window, it provides two formats: Master Boot Record (MBR) and GUID Partition Table (GPT). The former is older and only supports capacities up to 2TB, but is compatible with older versions of Windows. GPT is a newer format supporting larger capacities, but isn’t compatible with older versions of Windows.

Select the partition style and click the OK button to continue. If you accidentally closed the pop-up, right-click on the listed disk and select “Initialize Disk” on the pop-up.

If you didn’t get the pop-up warning, move on to Step 2.

Windows 10 New Simple Volume

Step 2: Right-click on the unallocated space, and select the New Simple Volume option on the pop-up menu, as shown above.

Step 3: The New Simple Volume Wizard begins. Click the Next button.

New Simple Volume

Step 4: Since we’re creating two partitions, divide the listed physical number in half. Type that number into the field next to Simple Volume Size in MB and click the Next button to continue. In our scenario, we’re dividing a 1TB SanDisk Ultra SSD.

Step 5: Allow the Wizard to assign a drive letter, or manually assign the letter using the drop-down menu. Click the Next button to proceed.

New Simple Volume Select File System

Step 6: Select a file system. Since your primary PC is Windows 10, use NTFS. Enter a volume label (drive name) too  — we used “Windows 10,” though you can label this partition with anything. Click the Next button to proceed.

Step 7: Click the Finish button to complete.

In Disk Management, the external disk should list one new volume — “Windows 10” in our example — and a second portion with unallocated space.

Right-click on that unallocated space and repeat step 1 to step 6. This time, however, choose exFAT as the file system during step 6, which you’ll use to share files with MacOS. Note that you don’t need to specify a volume size.

The result should look something like this:

Partition the drive on a Mac

Riley Young/Digital Trends

Partitioning an external drive in MacOS isn’t quite so annoying. Here we’ll assume that your external drive has no partitions, so we’ll need to create two. If you already have a Mac-friendly partition, skip ahead to step 5.

Like Windows 10, you may see an “initialize” error because the drive’s file system isn’t “readable.” Click the Initialize button on a small pop-up screen to create your first compatible partition, and then begin at step 5. If the error doesn’t appear, start with step 1.

Step 1: With Finder highlighted, click Go on the menu bar followed by Utilities on the drop-down menu.

Step 2: Double-click the Disk Utility icon in the following window.

Step 3: With Disk Utility open, your drive appears under External located on the left. Click Erase, located on the app’s top toolbar.

MacOS Erase External Drive

Step 4: In the following pop-up window, enter a name, select MacOS Extended (Journalist) as the format, and GUID Partition Map as the scheme. Click the Erase button to make these changes.

External Drive Create Mac Partition

Step 5: Once complete, your drive should have a single partition. Highlight the drive again in Disk Utility and click Partition instead.

Step 6: On the following screen, click the small “plus” button located under the blue pie chart to add a second partition.

Step 7: A second portion appears, slicing the pie graph down the middle. Enter a volume name, select the exFAT format, and click the Apply button.

External Drive Create Windows Partition

Step 8: Click the Partition button in an additional pop-up window to complete the process.

The result should look something like this:

Shared External Drive for MacOS Windows

Note that you’ll see icons on the desktop for both drives.

If you’re worried about the exFAT file system’s reliability factor, or a lack thereof, there is a way to format the secondary Windows partition to NTFS, but it requires connecting the hard drive to a Windows computer. You can review our Windows section for more information about this process.

Final notes

Paragon Software

That’s how you partition a hard drive for use on both Windows and Mac. Alternatively, you can install an application like Paragon (paid) or the open-source Tuxera (free) on your Mac to enable NTFS read/write support, but even with third-party software, some features, including Time Machine, will not work properly with an NTFS file system.