iOS 8 has arrived! We show you how to download and install iOS 8 as with our updating guide. Plus: find out how to get iOS 8 on your iPhone or iPad if you don't have enough space free.

iOS 8, Apple's newest software operating system for iPhone, iPad, iPad mini and iPod touch, launched on the evening of 17 September, bringing a plethora of great new features. Assuming you're up for it - and we discuss the pros and cons of updating in our complete guide to the iOS 8 launch - here's how to get iOS 8 on your iPhone or iPad.

If you are struggling to download iOS 8 we walk you through downloading it on your iPhone or iPad or via iTunes on your Mac or PC. The latter may be necessary if you don't have the excessive amount of storage Apple wants available for the download (see how to download on a Mac below).

Updating to iOS 8 is free (assuming your iOS device is compatible - we deal with that later), and pretty straightforward, although there are occasional problem to look our for. Follow our guide to downloading and installing iOS 8, and you'll be fine. We explain everything you need to do before downloading iOS 8, and help you avoid the pitfalls that may follow the update. And to remind you why it's all worth while read: 8 best new features in iOS 8.

Find out how to make space on an iPhone when you need it


Problems installing iOS 8

We had a complete nightmare installing iOS 7 last year - it took us all night. We had hoped things might go a bit smoother this year with the launch of iOS 8. But unfortunately not. As last year, many faced installation dramas because Apple's servers seemed unable to cope with the sheer number of people trying to access them to get the download. So if this was your experience with iOS 8 it's not a huge surprise, and you shouldn't feel like you're alone.

One thing is for sure, if you chose to update as soon as iOS 8 launched you were probably in for a long wait because the first few hours of an update are always the busiest time on Apple's servers. Coupled with the fact that America was awake so the demand would have been particularly heavy. If you are like us you tried to update to iOS 8 pretty much as soon as it was launched, you probably found that it was going to take hours (ours said 14 hours). Perhaps you even saw error messages and warnings that the update had failed.

If you want to avoid having a long wait for the download, we recommend you wait for a day or two, both because the rush will have died down and because some initial bugs and problems that weren't noticed in the beta testing phase will have been patched.

All that presumes you had enough space on your iPhone to start with. The main issue encountered by those trying to update was the fact that the iOS 8 update requires a lot of space to be available on your iPad or iPhone. When we tried to update it said we needed 5.8GB of storage available, even though it claimed that the iOS 8 update itself is just 1.1GB. Why does it need so much space? This is because it downloads a compressed file, unpackages it and then installs it. You need the space for the unpacking and the update. It also needs enough space for iOS 8 itself.

If you don't need to free up a lot of space you may be happy to delete a few images from your Camera Roll or some of your music. You might find it useful to read our guide to saving space on your iPhone here.

Luckily you don't really need all that space to be available - you can download the update via your Mac or PC. We show you how to do that below. Also read: How to improve iPhone battery life.

What to do before updating to iOS 8

Here are the steps you should take before you click yes on that update alert. 

1) Check your device is compatible with iOS 8

The following iPhones, iPads and iPods are compatible with iOS 8 – although that doesn't mean that they will be able to take advantage of every feature.

  • iPhone 6 Plus
  • iPhone 6
  • iPhone 5s
  • iPhone 5c
  • iPhone 5
  • iPhone 4s
  • iPad Air
  • iPad 4
  • iPad 3
  • iPad 2
  • iPad mini 2 with Retina display
  • iPad mini
  • Fifth-generation iPod touch

iOS 7's AirDrop feature, for instance, was limited to the iPhone 5 and later, the iPad 4, and the most recent iPhone and iPad mini. We're not yet sure which iOS 8 features will be device-limited, with the exception of Apple Pay (which is obviously restricted to the iPhone 6 and iPhone 6 Plus, which have the necessary NFC hardware).

For more information, read our guide to which iPhones and iPads are compatible with iOS 8.

2) Back up your data

Use iCloud or iTunes to back up your iPhone, iPad or iPod touch. If you don't do this, and you find that messages or photos disappear from your iPhone after the update then that's your look out. Beware: the backup will include purchased music, TV shows, apps, and books; photos and video in the Camera Roll; and device settings, but it won't include anything you synced from your computer. To re-sync that stuff you'll need to sync with iTunes. For that reason we recommend backing up to your computer as well as iCloud.

3) Make room on your device

If you have limited space on your phone you may not be able to perform the update - it's a fairly hefty download. To get ready, you can remove content you no longer need, which is a good idea in any case. See our guide to making room on your iPhone or iPad

Our iPhone required 5.8GB of space to be available in order to perform the update - since our iPhone is only 16GB this wasn't really an option so we opted instead to update via iTunes on our Mac. More on that process below.

4) Update iTunes on your Mac or PC

A couple of years ago people updated iPhones to iOS 6, only to discover that their iPhone or iPad could no longer talk to their Macs because they were running an old version of iTunes. This was made worse if they couldn't actually update to a version of iTunes that was compatible because they were running Mac OS X Leopard on their Macs. This was a big enough issue for Apple to actually start selling Snow Leopard again because it was the only way to get the Mac App Store - which is the only way to update to later versions of the Mac OS. Read: How to get Snow Leopard.

5) Plug in your iPhone or iPad

Make sure you plug in your device to a power source. If you run out of battery mid download you may corrupt the iPad or iPhone.

6) Make sure you're connected to WiFi

Be sure that you are downloading over WiFi and not via 3G or 4G, or you may end up using up all your data for the month. Read our guide: how to stop running out of cellular data.

How to download iOS 8 on your iPhone or iPad

The update is pushed out to your iPhone or iPad automatically. You just need to go into the software update section of Settings and accept the update. Hopefully you will be lucky and it will work first time, as in this video:

1) Go to Settings > General > Software Update

This will force your iPhone or iPad to check for the latest updates. (You may get an alert telling your that iOS 8 is ready, in which case you'll just need to tap download.)

2) Tap Download

Your iPhone or iPad will start to download the update.

3) Leave the update to download in the background

Once the download has finished you will receive a notification saying an update is available for your device.

4) Tap Details

This will take you to Settings > General > Software Update.

5) Tap Install Now

The iPhone or iPad will now start to install the iOS update. 

You can choose to leave the installation for later. Settings will display a notification badge until you have installed the update.

How to download iOS 8 via your Mac

This is what we had to do when it turned out iOS 8 required more space than we had available. You can view a video tutorial for these steps at the top of this article.

You need a lot of space to install iOS 8. When we checked General > Software Update we found that iOS 8 was 1.1GB in size but it required 5.8GB storage to be available to install.

Apple helpfully suggests that you can make more storage available by deleting items in Usage Settings, but that’s easier said than done, especially when you have a 16GB iPhone. We had just 1.4GB available on a iPhone 5s. Sure, we could have delete Music (3.6GB) and Photos & Camera (2GB) but that still wouldn’t be enough. And to be honest, we weren't keen to delete anything because we'd already slimmed down the iPhone considerably (having previously had a 64GB iPhone 5). Luckily there is another way.

Turning on the Mac and starting up iTunes gave us the message that “A new iPhone software version (8.0) is available for the iPhone “Karen’s iPhone”. Would you like to download it and update your iPhone now?”

Before clicking Yes, we quickly checked that the iCloud Back up was up to date. Last backed up on 14 September 2014 at 20.45 seemed a bit out of date, so we did a back up as that’s always a wise thing to do before updating. That took a few minutes.

Once backed up we clicked on Transfer and Update and the Mac began connecting to the iOS update server.

Then we clicked Agree to the software licence agreement. And when it asked for the passcode on the phone Touch ID was sufficient.

Here’s where we wish it was quicker, when we tried this on the night iOS 8 laucnhed, iTunes told us that there was 11, then 12, then 13 hours remaining. We're pretty sure that is longer than last year? We left it downloading overnight. Unfortunately by the morning the download had failed. Probably because the servers were overloaded.

This mornning we started the download again. Things moved a lot quicker this time. Once the iOS 8 update had finshed downloading to our Mac, it then switched to updating the iPhone firmware, eventually restarting the iPhone at which point we had various set up options to run through before iOS 8 was ready to go.

You can follow the whole process in the video at the top of this article. It did take a while, but probably only about 40 minutes from beginning to end.

How much space does iOS 8 take after installation?

At the beginning of the installation we had 1.4GB of space available on our iPhone (although iTunes on our Mac suggested that there was 2.7GB available). By the time the installation had finished we had 839MB of space left according to our iPhone (and 844.9MB according to our Mac).

That suggests that the installation has taken up 561MB of space on our iPhone (or if you go with what the Mac said, 1.8GB. It seems a strange discrepancy and we will try and get to the bottom of why the iPhone thinks there is less space than the Mac.

We have run an app that we use to clear junk files (CM Security), that cleared 362MB of junk files, so now we have 1.1GB space left. So 300MB is all we've lost - presumably that’s how much bigger iOS 8 is than iOS 7.

Reasons not to update to iOS 8 straight away

As we saw last year with iOS 7 - the biggest visual change of any iOS update - an update to iOS can make your iPhone or iPad look completely different. If you're scared of change, maybe wait a bit. (To be honest, though, that's less of an issue this year. iOS 8 looks very similar to iOS 7 - the main differences are all the lovely new features.)

Don't update if you rely on being able to jailbreak your iPhone. There's generally a delay before someone comes up with a jailbreak for a new iOS.

Remember Maps. Everyone who downloaded iOS 6 immediately then got hopelessly lost when they discovered Google Maps had been replaced by Apple Maps, as had a number of landmarks.

Beware of bugs. Every new update brings with it bugs that somehow got missed in the testing process. Beware: your iPhone or iPad might just stop working if it doesn't like something about iOS 8. Let others discover the problems first.

The latest version of iOS might break your apps. Before you update to iOS 8 make sure that your existing apps are up to date and that you have a backup of your iPhone or iPad.

For example, last year Kindle warned that if you didn't update your Kindle app before updating to iOS 7 you might have to download your books again. A Kindle update to version 3.9.2 was necessary before updating to iOS 7.

Don't download if you aren't at home - it's easier to troubleshoot when you are in the same room as your Mac or PC, and have access to WiFi.  

If your iPhone is a work phone, hold fire… Updating may break your work email or critical apps. Try explaining that to your boss.

Beware battery life problems. Sometimes iOS updates have a tendency to affect battery life.  This is the kind of thing that someone else can discover for you.

Remember you generally can't go back after you install a new version of iOS.

We look at whether you should update to iOS 8 here, and ways to downgrade from iOS 8 here.

Find out what to expect from iOS 8 – read our iOS 8 review here.