How Long Does Migration Assistant Take Title Image

You’ve just spent nearly $2000 on a new M1 Mac.

Treating yourself to the newest Apple hardware is great. But now you’ve the prospect of migrating everything from your old Mac to your new.

Is it going to take ages? How long will the Migration Assistant app take?

We’ve crunched the numbers.

Read on to see how your move options compare. And then you can decide how you want to move your files over.

How Long Does Migration Assistant Take?

Wifi: 250GB over 802.11ac WIFI takes approx. 2 hours 44 minutes.

Ethernet: 250GB over 1Gbit Ethernet takes approx. 33 minutes. SSD Drive with Mac backup of Time Machine: 250GB takes approx. 40 minutes.

The migration speed of your data depends on:

1. How much data you’re transferring – how many files and apps you have. And on the size of those files.

2. How you’re transferring your data – the method you use.

3. And the type of cable you use. When transferring peer to peer over Ethernet.

Let’s look at some real world examples.

Migration Assistant Uses 3 Main Ways

Mac Migration Assistant uses one of 3 ways to move your data, files and apps from one Mac to another.

And so, when you’re told it could take anything from 10 minutes to several hours.

You wonder. How can that be?

One of the reasons it’s difficult to nail down an answer is because you can shift your data these ways;

1. Mac to Mac over WIFI.

2. Mac to Mac over Ethernet. Also known as Peer-to-Peer.

3. By using a Time Machine back up of your old Mac to move your content to the new Mac.

And each method comes with its own pros and cons. And the key is to understand what those are for your particular situation.

So, let’s look at the first way.

How Long Does Migration Assistant Take Over WIFI?

The transfer of 250GB of data over 802.11ac WIFI from an old MacBook Pro would take 2 hours 44 minutes.

It appears this method is Apple’s favored way of migrating. It’s the way they highlight in their online documentation. Using the Migration Assistant app Mac to Mac over WIFI.

And for sure you don’t need much supporting equipment. But should it be your favored way?

And to answer that question let’s look at the typical wireless network.

The WIFI speed you get depends on the WIFI standard your router supports. Most routers support the 802.11ac standard.

But watch out if your router works to an earlier standard. As you’ll get a response much slower than the figures here.

802.11ac has a top theoretical speed of 1,300 Mbps. But in the real world you’ll get something more like 200 Mbps.

Why so much less?

It’s because of WIFI protocol overheads.

And interference in and around your home affects the speed you’ll see. Your router being in another room, behind walls and doors will affect your speed. As well as general interference from radio waves and any other wireless network nearby.

And you have the little sleight of hand trick that manufacturers use. 200 Mbps sounds huge. Until you realize that it is 200 megabits per second. Not Megabytes per second.

So what?

Translate your 200 megabits and it nets down to about 26 Megabytes per second.

A Worked Example Of Migration Assistant Over WIFI

How close your old and new Mac’s are physically to each other is a factor in how long the data migration takes. Aim to have them as close together as possible.

And close to your WIFI router helps.

Source – MacBook Pro Mid 2010 with a 250GB Hard drive that’s pretty much full.

Target – Intel based new MacBook Pro 2020 with SSD.

The old computer supports the 802.11ac protocol so that’s great. And so does the router. And of course, the new 2020 Intel based MacBook does too. From a Wi-Fi point of view I have the best case scenario.

How Long Could Migration Assistant Take Over Wifi

Here’s how you work it out:

A full 250GB hard drive on the 2010 Mac to transfer over Wi-Fi. How many Megabytes of data would that be?

250GB x 1024 = 256000 Megabytes of data.

@ 26 Megabytes per second max 802.11ac WIFI speed.

Gives you 9846 seconds. And that’s 164 minutes. And so would take 2 hours 44 minutes.

At full WIFI speed. And this assumes you’ve no other issues slowing your WIFI down.

It’ll max out your WIFI. So don’t expect to be watching YouTube on your Apple devices like your iPad at the same time.

Jeez you’re gonna need some patience shifting over WIFI.

How Long Does Migration Assistant Take Peer-To-Peer Over Ethernet?

The transfer would take about 1 hour and 33 minutes on an old hard drive based MacBook Pro. And 33 minutes on a 2017 SSD based MacBook Pro. Using Apple Migration Assistant peer-to-peer over Ethernet isn’t often talked about.

Using Apple Migration Assistant over Ethernet isn’t often talked about.

But you might want to consider it.

You’ll need a 1Gb Ethernet adapter cable to direct connect your old Mac to your new. The Ethernet cable must support the 1Gb standard. If it doesn’t. You’ll end up moving your user data at a slower speed. And it’ll take you much longer.

Oh, one other thing. It’s worth noting here that the Ethernet standard is talking Gigabit. Not Gigabytes.


A Gigabit is 8 times smaller than a Gigabyte.

Got your cable? And your Mac’s connected? And your previous Mac – your source Mac in Target Disk Mode?

Good. Let’s look at a worked example.

How Long Should Migration Assistant Take Over 1GB Ethernet

A Worked Example of Migration Assistant Over 1Gb Ethernet

Try and keep your Ethernet adapter cable as short so you can to max out the speed you’ll get. Because a bit like WIFI the further apart your Mac’s are the more it can affect the speed.

Source Mac – MacBook Pro Mid 2010 with a 250GB hard drive that’s full.

Destination Mac – Intel based MacBook Pro 2020 with SSD.

Working with the raw figures and with the right cable. A full 250 Gigabyte hard drive.

Times 8 to get your Gigabit figure = 2000 Gb.

And as our Ethernet speed is 1Gbit per second.

2000 divided by 60 gives us 33 minutes just over.

Sounds way better than WIFI.

BUT hold on ONE second before you skip away.

Migration Assistant, Ethernet On An Older Mac

The Ethernet port on the older Mac will work at 1Gb/s. But it’s unlikely that old Mac can shift the files out at that speed …


Because the read speed of the hard drive on the 2010 MacBook is 45 Mbytes/s.

Translate that 45 Megabytes per second into something we can work with.

45MB x 8 = 360 megabits. And that means in Gigabits .36 of a gigabit per second.

Note: 1 megabit is equal to 0.001 gigabit.

That nets out at around a 3rd of the speed of the port.

2000 gigabits @ .36 of a gigabit per second = 5555 seconds = 92 minutes.

And brings us up to a more realistic 1 hour 33 minutes.

But a bit over half the time of WIFI.

This is pretty much worse case scenario. With a really old but much loved MacBook. With a newer Mac, particularly one with SSD drives then the time take will be quicker.

Let’s look at that.

What About If You Had A Faster MacBook Pro?

Say for example a 2017 MacBook Pro with a 256GB SSD drive.

What would the migration process look like then?

You’d have the same raw Ethernet performance. But you’ve a much faster internal drive on the Mac. A drive that can ship your data, files and folders out across that Ethernet much faster.

You’ll have a read speed of 2259 MB/s. We have to convert Mbytes into Megabits.

2259MB x 8 = 18072 megabits.

Then convert to gigabits per second give you 18.072 gigabits.

And that means this MacBook’s internal drive is much faster. It’s faster than your 1Gb/s ethernet connection.

So, in this case the speed of the internal drive is not a factor. And your back to the speed of the Ethernet connection. And that means your Mac transfer of all your data from a 2017 MacBook Pro would take around 33 minutes.

Faster than using WIFI.

How Long Does Migration Assistant Take From A Time Machine Backup?

Migrating this way means using Mac Migration Assistant with an external backup drive.

A drive with your Mac Time Machine backup on it. Or if you haven’t taken one already. You take a Time Machine backup of your old computer.

You then use that backup drive with Migration Assistant to move all your files.

Let’s have a look at a typical external hard drive first.

How Long Would It Take With Migration Assistant With A Hard Drive?

Taking a look at a reasonably performing modern hard drive. The WD Elements portable with your Time Machine backup on it.

The read speed is around 105MB per second.

You’d plug that new drive into your new computer’s USB port.

New Mac’s have SSD drives in them. And their write speed is much faster than the external hard drive speed.

And that means the SSD drive inside your Mac won’t be a bottle neck.

Migration Assistant On A Hard Drive

Here’s how you work it out.

250GB stored on the WD Element drive transferring out to your Mac at 105MB per second.

To work this out you’d convert 250GB to Mbytes.

250GB x 1024 = 256000 Megabytes of your files.

256000 divided by 105MB gives you the number of seconds 2438.

Around 40 minutes for the Migration Assistant transfer. Not bad.

About the same time as a direct Mac to Mac Ethernet connection. And certainly a route to go if you’ve got an older Mac with a slow internal drive inside it.

Take a backup and use a faster hard drive with Migration Assistant.

How Long Would Migration Assistant Take With An SSD Drive?

Looking at the Samsung T7 SSD drive.

It’s read speed is 887 Mbytes per second.

With your Mac Time Machine backup on it. Plugged into your new Mac’s USB port and used with Migration Assistant.

Your new computer’s internal SSD drive is going to operate at a faster speed than an external USB SSD drive.

The reason is, a new Mac’s design places the drive close to the Mac’s processing power. And its memory and cache to reduce delay. Plus, it doesn’t have the overhead of the USB protocol that an external solid state drive has. 

The speed of the external SSD is going to be the main factor here.

Migration Assistant On A SSD External Drive

Let’s work it out. Again, converting 250GB to Mbytes

250GB x 1024 = 256000 Megabytes of folders and files.

256000 divided by 887 tells us the number of seconds = 288.

Just under 5 minutes. Now that’s crazy whizzy.

And worth the cost of a new drive.

Other Advantages Of Using An External Drive With Migration Assistant

It’s not just that using an external drive is faster, much faster than WIFI. It’s also pretty comparable to directly connecting each Mac using 1Gb Ethernet.

And if you’ve an SSD drive its way faster.

Other plus point are;

1. Often you’re moving to a new Mac because your old Mac is failing.  Stressing a failing Mac for hours doing your data migration over WIFI. Is best avoided. And it leaves your WIFI free for you to use.

2. It’s a good idea to have a Time Machine backup of your old Mac anyway.  Just in case. Of course, you can keep hold of your old Mac for a while. But if you decide to sell it or give it away you can always get to files you need from your backup.  

3. Freeing up your old Mac while Apple Migration Assistant uses your backup to build your new Mac. Means you have a computer you can use while your new Mac is set up.

But using an SSD is so fast you wouldn’t have long to wait anyway.

Speeding Up Migration Assistant

When you’re looking at migration speed. How fast the Migration Assistant migration process goes depends on the way you do your transfer. And the amount of data you’re moving.

Moving your data, files and apps over WIFI is the slowest.

1Gb Ethernet is the next fastest way to speed Migration Assistant up.

Migration Assistant used with a hard drive is comparable to the speed of 1Gb Ethernet. And a hard drive is certainly faster if you’re Ethernet is slower than 1Gb.

Using an external SSD drive is the fastest way of moving your files. And speeding up Migration Assistant.

How Fast Is Migration Assistant On Mac?

The speed of Migration Assistant is not about your Mac’s speed. It’s about what you use Migration Assistant with.

250GB carried over 802.11ac WIFI could take 2 hours 44 minutes.

Compared to.

250GB shifted over 1Gb Ethernet would take 33 minutes from an SSD based Mac.

250GB transferred using an external hard drive could take 40 minutes.

Compared to.

250GB moved with an external SSD 5 minutes.

In Closing

You would scale up the figures above if you were moving twice the data.

And scale down if you’re moving less. The illustrations allow you to do your own calculations and work things out for your own file move.

Now you have an idea of how long Migration Assistant would take.

And know the relative speed and time merits of each way. You can pick the quickest and easiest way for you.

Want to read more about using Migration Assistant?

Review some of our other related articles.

Related Articles

Does Migration Assistant Transfer Everything [Need to Knows]

Restore From Time Machine To A New Mac (Whoosh)

What Should I Transfer To My New Mac [Non Techie Or Techie]

Migration Assistant VS Time Machine Now Know The Difference

How To Transfer Applications From One Mac To Another

What Does Migration Assistant Transfer [And Does Not Transfer]


SoftPerfect Knowledge Base Speed Discrepancy: MB/s and Mb/s

How Fast is a WIFI Network

Megabits VS Megabytes and Why It Matters


  1. Simon,
    I have just received my new 24inch iMac and am migrating all the data from my 21.5 inch 2010 iMac. I came across your site and just wanted to say a huge thank you to you as reading your articles on migration made more sense than anything else that I found on the internet.
    Great work.
    Thanks again

    1. Hi Steve,
      Thank you for taking the time to leave a comment. I’m so glad you found the post helped you. Your comment makes it all worth while.

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