Connect an External Hard Drive to Mac, 12 Things You Need to Know

By Simon Irons / August 29, 2019
Connect An External Hard Drive To Mac Title Image

It doesn’t matter if it’s your photos from that special holiday. Or your mega music collection in iTunes.

You want to know how to connect an external hard drive to your Apple Mac. And you need to know now.

Because you need a backup of your important stuff.

In this article Connect External Hard Drive to Mac. You’ll find out the 12 things you must know to hook up an external hard drive.

You’ll like this article if you have a MacBook, or MacBook Pro or MacBook Air.

Or if you have an iMac.

Or if you’re running Mac OS Sierra or higher.

You’ll find your connection options from your MacBook late 2010. Through to the connection options on your 2015, 2016, 2017 and 2018 Macs.

You’ll find the answer to these questions;

How to connect an external hard drive to a Mac?

How to find the external hard drive on a Mac? And the answer to some other questions you may not have thought of yet.


The delivery man is here.

Your external drive hard has arrived.

Go on, remove the packaging.

And you’ll find inside;

  • Your external hard drive.
  • A USB cable.
  • Is there a power adaptor?

You’ll need one only if your hard drive isn’t powered by your USB cable.

Now take a look at your Mac and find out what ports it has.

1. USB Connections and your Mac

Your USB (Universal Serial Bus) cable connects your Mac and its external hard drive. This cable allows your Mac to transfer files to and from your external drive.

Your USB cable can also provide the power to your drive.

Assuming your drive is USB powered as many of the portable external hard drives are now.

Your USB cable is a standard cable, yes.

But there are different ‘standards’ of USB cables and different plug connections. And what your Mac needs depends on when your Mac was made.

Your Mac used the best USB standards of the time.

But as the USB standards progressed, the physical connections changed. And the speed files were sent between a Mac and its external hard drive increased.

And the electrical power supported changed. The newer USB cables carry more electrical power compared to earlier USB cables.

2. USB External Hard Drive Compatibility on an Apple Mac

The great thing about the USB standard is its inbuilt backwards compatibility.

For example: USB 3.0 is backwards compatible with USB 2.0.

USB 3.0 is the faster protocol (5 Gbit/s minus overheads).

External hard drives that meet the USB 3.0 standard send their files at USB 3.0 speed. As long as your USB 3.0 external drive is connected to a Mac with a matching USB 3.0 port.

But what happens when a USB 3.0 external hard drive connects to your Mac with a USB 2.0 port. Your drive will send files to and from your older Mac at USB 2.0 speed. (480 Mbit/s minus overheads). 

Great because it means your older Mac can use the newer, external hard drives.

It doesn’t matter whether your Mac is an older so slower Mac. Or a newer faster Mac.

Or if your external hard drive is slower or faster than your Mac. Your Mac and the drive will work out who can do what. And at what speed.

3. Connecting an External Hard Drive Your Older Apple Mac

When you look at the ports on your Mac. Do they look like this?

USB Type A Ports on the Mac
USB Type A Ports on the Mac

These are type A USB ports.

Older Macs.

For example if you have a MacBook Pro 2010 it will have type A ports that support USB 2.0.

Macs with USB 3.1 gen 1 and 2 ports will also have type A ports.

Along with Macs with USB 3.0 ports.

They all have type A ports.  

And it means all the ports on all those Macs look the same. And use the same connector to plug in.

Your USB cable will look like this at the end that plugs into your Mac.

USB Type A Cable at the Mac End
USB Type A Cable at the Mac End

And your USB type A cable end may have a colored blue strip in the connector. If it does this will help you spot with what type of cable you have.

Does your external hard drive have a type A plug on the end for your Mac?

Does your Mac have type A ports?

Yes, then you’re good to plug in.  If not read on.

4. Connecting an External Hard Drive to a MacBook Pro 2011

Check. Does your Mac have a Thunderbolt 1 or 2 port?

Depending on the age of your Mac it may have a Thunderbolt port as well as USB type A ports.

How can you tell?

Apple introduced the Thunderbolt USB ports with the 2011 edition of the MacBook Pro.

You’ll see these ports because they have the tell tale lightening bolt symbol beside them.

Thunderbolt Port Alongside USB type A Port on Mac
Thunderbolt Port Alongside USB type A Port on Mac

You can plug a type A USB cable end straight into your Mac’s type A ports.

Or if they are full and you want to use the Thunderbolt port then …

The Thunderbolt ports are faster. And were made for connections to a Thunderbolt screen, or FireWire or gigabit Ethernet. As well as external storage.

You’ll find the port looks very like a mini display port. But it is not the same so don’t get them mixed up.

That’s why Apple put the lightening bolt symbol right next to the port.

The beauty of Thunderbolt is that it can connect many devices at the same time.

You’ll notice that the Thunderbolt ports are different to USB type A ports. If your Mac has one of these ports and you want to use it, you’ll need a USB cable end that looks like this.

Thunderbolt Cable Connection
Thunderbolt 1 and 2 Cable Connection

If you have a type A USB cable end from your external drive for your Mac then you’ll need to get yourself an adaptor. Or adaptor cable. Then you can plug any USB 3.1, 3.0 or 2.0 external hard drive into your Mac’s Thunderbolt port.

Because apart from the different physical connection it will work.

Here is an example for you of an adaptor you can buy from Amazon.

Kanex Thunderbolt eSATA plus USB 3 Adaptor

You can find more info on Apple Mac ports in this Apple article on the Apple website.

Identify the Ports on your Mac

5. Connecting an External Hard Drive to a MacBook Pro 2015

USB C type connections were introduced first on the MacBook 2015 edition. The 2015 MacBook had a single USB C port, which supported the speed and protocols of USB 3.1 gen 1.

You’ll know you have one of these ports because you’ll use it to charge your MacBook.

The good news is that you can get an adaptor cable so that you can use an external hard drive.

Strange. This particular port does not support Thunderbolt devices or displays.

So there is no point you buying a Thunderbolt external drive to connect if you have a 2015 MacBook. A USB 3.0 or 3.1 drive will work fine with the right adaptor.

6. Connecting an External Hard Drive to a MacBook Pro 2017

Your newer iMac (2017 onwards) and iMac Pro.

Mac mini (2018)

And Macbook Pro (2016 and later) and MacBook Air 2018, 13 inch with Retina display came with USB C type Thunderbolt ports. And they look like this.

USB C Thunderbolt 3 Ports
USB C Thunderbolt 3 Ports

All those ports support Thunderbolt devices and are Thunderbolt 3 ports.

So if you really need a fast external hard drive you can by a Thunderbolt 3 drive. Put it on and your good to go. …

They do come in at quite a price.

Don’t worry, again because of USB’s backwards compatibility, you can put USB 3.1, 3.0 and earlier external hard drives on.

And all you’ll need is the right adaptor cable.

Here is the Apple one and its on Amazon.

Apple USB-C to USB Adapter

Ok, now you’ve had a run through on the different type of USB ports and cables.

Got yourself an adaptor cable if you need one. It’s time to plug in your external hard drive into your Mac.


I found for you this document on Apple’s website. It shows the different type of ports available on the different MacBook generations. And the different kinds of adapter cables you can get for your Mac. You may find it useful.

Adaptors for Thunderbolt 3 or USB C Port on Your Mac

7. Powering Your USB External Hard Drive from Your Mac

As the USB standards moved forward, drives got bigger and faster. And so external drives needed more power.

The USB cables became thicker to move your files faster and to power the drives.

So what does this mean for you?

Are you wanting to replace a shorter USB 3.1 cable on a Mac with a USB 3.1 port. And are you connecting an USB 3.1 external drive?

Want the top line speed your USB 3.1 external hard drive is capable of? You’ll need to buy a USB 3.1 type A replacement cable.

But.

If you’re buying a USB 3.1 external hard drive. And plan to connect it to your Mac with a USB 3.0 or a USB 2.0 port.

Your Mac can’t send your files to the drive at USB 3.1 speed.

But you can buy yourself a longer USB 3.0 cable. Backwards compatibility means your USB 3.1 external drive would work. And at the speed your Mac is able to work at.

8. Does your External Hard Drive need a Power Cable on Your Mac?

Typical External Hard Drive Power Cable
Typical External Hard Drive Power Cable

Desktop external hard drives typically need a separate power plug.

If you’ve an external power adaptor for your drive, don’t turn on the power yet. Put your external drive on a firm surface before you power it up.

Spinning, powered up drives, won’t appreciate knocks and shakes. You’ll shorten the life of your hard drive.

And risk corrupting your files.

Unless you have a Solid State drive (SSD). SSD’s don’t have moving parts. And you wont have to be so concerned.

External drive on a firm surface? Good. Power it up.

You may hear the fan or see a light come on the front of your drive to tell you it’s powered and working.

9. Now Connect Your External Hard drive to your Mac

Open up and sign into your Mac then plug in its USB cable. Plus the adaptor if you’re using one.

If your drive is USB powered it will power up when you connect the USB cable into your Mac.

10. Now Your Drive is Connected, How do You Find Your External Hard Drive on your Mac?

There are several ways to find your connected external hard drive on your Mac.

First look at your Mac’s desktop screen. Within a few seconds you should see a new icon on the desktop. That icon lets you know your external hard drive is connected and seen by your Mac.

External Drive Icon On Desktop
External Drive Icon On Desktop

Double click to open up a window to the drive so you can see your nice empty drive.

You can also find your external hard drive in a finder window on your Mac. Open up a new finder window and you’ll see your drive listed under devices.

External Drive In Finder Window
External Drive In Finder Window

f your external hard drive is not there either as an icon or in the finder window. Check the frequently asked questions below.

11. How you use Your Connected External Hard Drive on Your Mac

Using a connected up external hard drive on a Mac is as easy as using any other finder window on your Mac.

Just as you would copy and paste from one finder window to another on your Mac. You can copy and paste to your hard drive’s finder window.

Once your finder window is open on your connected external hard drive. You can use all the commands you’re used to using.  

You can drag and drop.

Or copy and paste from a finder window on your Mac to a finder window on your hooked up external hard drive.

As long as your drive is connected, your Mac treats your external drive the same as your internal drive.

12. Disconnect Your External Hard Drive from Your Mac

The last important thing for you to know is how to disconnect your external hard drive.

That way you’ll be sure you’re not accidentally corrupting the files you have on there.

You do this by ejecting your external hard drive from your Mac computer. 

Hover over the external drive icon on your desktop.

And right click. Choose the Eject option from the menu that comes up.

Right Click to Eject External Drive
Right Click to Eject External Drive

Or go to the finder window of the connected external hard drive. And click the arrow to the right of the drive name. That will also eject the hard drive.

External Drive In Finder Window
External Drive In Finder Window

Wait a few seconds for the external drive icon to disappear.

This makes sure your Mac writes whatever it needs to the disk.

You may hear the fan on your external hard drive wind down.

Or the light on the external hard drive flicker and go out. Or flicker and stay steady.

Now you can remove your USB cable from your computer. And your power cable if you have one for the external hard drive you’re using. 

You can now safely pick up and move your disk drive.

Connect An External Hard Drive to Mac Frequently Asked Questions

1. How do I find out what ports and what USB Types my Mac supports?

If you’re not sure from looking at the pictures in this article, then there is another way to find out.

Look at the top left of your desktop. Click on the Apple symbol. And pick the option “About this Mac”.

About This Mac Screen
About This Mac

Your next popup window lets you to choose different options that tell you what is on your Mac. And what your Mac is capable of.

Choose System Report
Choose System Report

Pick System Report.

The next popup window will show you all the hardware you have on your Mac.

Find Out What You have on Your Mac
Find Out What You have on Your Mac

Pick USB.

Click on each arrow to expand the USB section so that you can see what you have.

You’ll then see whether you have USB 2.0 or USB 3.0 or 3.1. This page on the Apple website is useful for more information as well.

Using USB devices with your Mac

2. Your Connected External Hard Drive Not Showing Up?

Can’t see your connected hard drive on your iMac or MacBook Pro or MacBook Air.

There are a few things you can try.

2.1 Check your Finder Preferences

Finder Preferences
Finder Preferences

Be sure to check ‘Hard Drive’ and ‘External Drive’ on your finder window preferences.

Finder Preferences Show External Drive
Finder Preferences pick to Show External Drive

Then your external hard drive will show up on your desktop.

2.2 Another thing is sometimes stuff can happen to the software on your USB port on your Mac.

For example if you had something else plugged into the port. And it wasn’t disconnected properly. Try plugging into another port on your Mac. Does the connected external hard drive show up on your Mac? No? 

Then a Restart of your Mac will reset all the external ports and sort any issues. 

2.3 If you’ve an older Mac 2010 or earlier.

And you’re using a new USB 3.0 portable drive powered by its USB cable. It could be the power needed by the drive is more than the USB 2.0 protocol supports.

This is an issue with some of the external hard drive manufacturers. The ones who didn’t stick to the USB standards.  I guess they think all the older MacBooks should be retired.

Check on the power draw of your drive. If it is too much you may need a drive powered by an external power cable.

3. Your Mac won’t use your Connected External Hard Drive

Can you see what is on the drive? Can you open up documents but you can’t update or put any files on the drive?

And the drive seems some how write protected. Or read only. Then the odds are you have an external hard drive in a format your Mac can’t write to.

You may already know the external drive was on a Windows PC. Some external hard drives are delivered to work on a PC. They have a file system called NTFS. NTFS is a file system a Windows PC can use straightaway.

But your Mac can only read it. And copy files off.

You’ll need just a little more effort for the drive to work on a Mac.

It will need formatting to work on your Mac.

Don’t worry. Know that in a few minutes you’ll have the drive up and running. Want to know how? You can learn how here.

Once you’ve formatted the drive. You’ll be happily playing, copying, pasting and backing up all you want onto the drive.

Formatting wipes all the documents on the external hard drive. If you don’t want to do that but still need to use the external drive on your Mac. Take a look at my article here.

It goes through your options for using an NTFS drive without reformatting on your Mac.

Last Words

And now you have the 12 things to know when you connect an external hard drive to Mac.

Now you’re in the know, are you ready to choose an external hard drive for your Mac? Take a look at some of the best.