Normally when you plug in an external hard drive to your Mac’s USB port you will see it appear on the desktop. You can also see it in a Finder window in the left column under Locations (or Devices in older versions of macOS). If the drive is not showing up on your Mac chances are it has not been formatted correctly, has been corrupted, or is faulty. Alternatively, you may have set a password for the drive that you need to enter before it will connect.
We show you how to work out whether the reason the external drive is not mounting on your Mac up is due to a problem with the drive itself, the cable or the port, and how to resolve the problem and access data on your drive.
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This article assumes you have an external drive that should connect to your Mac via the USB-A, USB-C, or a Thunderbolt port. If you have a NAS drive that connects over the network then you should read our article about connecting to a NAS drive.
Why is your hard drive not showing up on Mac?
We’ll start by trying to identify the reason why your hard drive isn’t showing up on the Mac before explaining what you need to do to find the hard drive on your Mac. If you can identify the cause your should be able to fix the problem that is stopping your external drive from opening on your Mac.
Damaged cable, port or insufficient power
The first port of call is always to check that it’s plugged in, but we are sure you have done that. The problem might be with the cable.
One of the main reasons why drives fail to mount is if the drive isn’t receiving enough power. If the drive is powered via a USB-A cable you need to check that adequate power is being delivered to the drive. Very old Macs may require a USB power cable, a cable that splits into two USB connectors that need to both be plugged into your Mac, in order to deliver enough power to the drive. Similarly, make sure that the drive doesn’t have an external power supply it should be using.
On the subject of cables, make sure that it’s not at fault. Try using a different cable with the drive to see if that fixes the problem. Similarly, if you are using a USB port on a hub check that’s not what’s causing the problem.
Also check that the port on your Mac isn’t the problem. Try using a different port. Or if you only have one port, plug another device in and see if that works.
The next step is to try plugging the drive into another Mac. If it also fails to mount there you will know that there is a problem with the drive while if it does mount then the problem is with your Mac.
Problem preferences
Hopefully, there is a really easy fix to get the hard drive to mount on your desktop. Try the following to make sure your Mac is set to show mounted drives on the desktop.
- Open the Finder.
- Click on Finder in the menu at the top of your screen.
- Click on Settings (Preferences in older macOS versions).
- Click on General.
- Make sure that there is a tick beside External disks.
If it was already set up so that the external drive would appear on the desktop then continue to follow the steps below.
Password protections
You can protect a drive with a password when you initially start using it, so check to see if the reason your drive isn’t mounting is that a password request box has popped up and you didn’t notice it.
Sometimes the password popup takes a few minutes to appear as well, so it helps to be patient.
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The drive is formatted for a PC
It is possible that the drive has been formatted using a file system that your Mac cannot read.
- Windows PCs use NTFS or ExFAT file formats.
- Mac computers before Sierra used the HFS+ file format.
- In High Sierra, Apple introduced a new file system called Apple File System (APFS).
- There is an old FAT32 format can be read by Window and Mac computers, but has limitation on what files can be stored.
An easy way to find out if this is the problem would be to check on a PC. If the drive mounts on the PC it’s likely that you have discovered what the problem is: the drive is formatted for PCs and can’t be read by your Mac. 
To make sure your drive can be read by Macs and PCs you need to format it using exFAT or the older FAT32. We’ll explain how to do that below.
It’s a corrupted or faulty drive
If none of the above were the reason why you couldn’t see the external drive on your Mac, perhaps the drive is faulty. If it is, you can use Apple’s Disk Utility program to access the disk and potentially fix whatever is causing the issue. We’ll discuss how to do that below. We’ll also look at ways you can stop a drive failing in the future.
How fix an external drive that won’t show up on a Mac
If none of the above solved your problem, it is likely the drive is either formatted incorrectly or damaged.
Depending on the reason why you can’t see the drive, here is what you need to do to get it working.
How to reformat a drive so you can see it on a Mac
Hopefully, the drive is fine, but the format is wrong.
It is possible that the hard drive has been formatted using a different file system (i.e. on a Windows PC). In that case, if you need to access the data on the drive you’ll need to connect the drive to a Windows PC that does recognize it and copy the data before moving on to the next step because the process will involve reformatting the drive and deleting everything on i).
- To make sure your drive can be read by Macs and PCs you need to format it using exFAT or the older FAT32.
- If you want to format the drive to just be used on a Mac you can use the HFS+ or Apple File System (APFS) file formats.
Having got the data of the drive via a PC you can reformat the drive so that you can add the data again. Here’s how to reformat your drive so it can be read by a Mac or a PC.
- Open Disk Utility (as per the steps above).
- If you don’t require the data on the hard drive, select the disk and click Erase.
- Before Disk Utility starts to erase the disk it will pick a format for you. You can change this if you click on the Formatting options. Choose your format, ExFAT if you want to make sure it’s compatible with PC and Mac, otherwise, Mac OS Extended (Journaled) is probably the best option.
- Click on Erase and wait for your Mac to erase and then reformat the drive.
- Give the drive a name.
Screenshot
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Read more: How to format a drive on a Mac.
How to fix the faulty drive with Disk Utility
If the various checks above suggest that the disk is faulty then you can use Apple’s Disk Utility program to access the disk and potentially fix whatever is causing the issue. Here’s what to do:
- Find Disk Utility by opening Spotlight (cmd+Space-bar) and start typing Disk Utility, press enter to open the program.
- Look in the column on the left to see if the hard drive appears there.
- If you can see the hard drive in Disk Utility check underneath it for a volume. If it is there click on it and select Mount. If your Mac has already mounted the drive the option Unmount will be displayed instead. (If there is no volume listed your Mac is not able to access the drive. The Mount option will be greyed out.)
- Your options are First Aid, Erase, and Restore. First Aid will check the disk for errors and then repair the disk if necessary and this is the option to choose. Restore allows you to erase the contents of the drive and replace that with data from somewhere else. Erase deletes all the data stored on the drive. If you need the data on the drive do not choose Erase or Restore!
- Click the First Aid tab and select Run.
- If after running First Aid the Mac finds errors you could fix you may see the option to Repair Disk. If you do, go ahead and run the repairs.
Best apps to recover data on a lost drive
If your Mac is unable to repair the disk if is likely that the drive is either formatted using a file system that the Mac cannot read, or it is well and truly broken. If it’s the latter we suggest you follow this tutorial about recovering data from a damaged disk. You may also want to consider one of the data recovery apps for Mac we recommend in our round-up of the Best data recovery apps for Macs.
Our recommendations include Recoverit from Wondershare, Data Rescue from Prosoft and Stella Data Recovery for Mac.
How to prevent issues with hard drives on a Mac
We have final suggestion to make that is more of a guard against this error happening again.
Make sure that your external drive doesn’t become damaged in the future by always unmounting the disk properly after using it. Don’t just unplug the USB cable.
To unmount your drive you can right-click (control-click) on the icon on the Desktop or in the Finder and choose Eject. Drive issues can occur when the disk is removed without ejecting it properly.
Decided there is no hope for your faulty hard drive? We have a round-up of some of the best we’ve seen here: The best Mac hard drives.
Author: Karen Haslam, Managing Editor, Macworld
Karen has worked on both sides of the Apple divide, clocking up a number of years at Apple's PR agency prior to joining Macworld more than two decades ago. Karen's career highlights include interviewing Apple's Steve Wozniak and discussing Steve Jobs’ legacy on the BBC. Having edited the U.K. print and online editions of Macworld for many years, more recently her focus has been on SEO and evergreen content as well as product recommendations and buying advice.