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How we test cloud storage services

By Christina Woodger

Discover the steps Which? goes through to recommend the best cloud storage services for your files, photos, music and documents

Put us to the test

Our Test Labs compare features and prices on a range of products. Try Which? to unlock our reviews. You'll instantly be able to compare our test scores, so you can make sure you don't get stuck with a Don't Buy.

We put cloud storage services through a demanding range of tests and checks, and our independent reviews help you pick one that’s easy to use and which looks after your files securely.

Our reviews answer the most crucial questions about cloud storage services, including:

  • Is it simple to install and set up?
  • How easy is it to sync files?
  • How quickly can you upload and download files?
  • Does it have good security procedures?
  • How easy is it to use on a smartphone or tablet?
  • How much storage space do you get?

Head to our cloud storage reviews now to find out which are worth considering.

Cloud storage ease of set-up

Our tests aim to cover every element of using a cloud storage service. First impressions matter, which is why we inspect the simplicity of installing and setting up each one.

An easy-to-follow tutorial for use, and clearly-stated terms and conditions get a thumbs up from us, but we have no qualms in shining a light on those that seem to take pleasure in confusing you.

Syncing files on cloud storage

Cloud storage services give you a safe backup location for your files. With your files backed up online, they can also be synced between devices - make changes to a file on one device, and they'll show up when you view the file on another. As saving files is such an important element of a cloud storage service, the syncing process should be as straightforward as possible.

We look at whether there’s any automatic and real-time synchronisation of files, or whether your only option is manual uploading. Plus, we look at whether it gives you clear messaging regarding whether files have been successfully synced.

How quickly can you upload and download files?

We look at how long it takes to upload and download photos and videos, to help prevent you tapping your laptop in frustration at a storage service that takes its sweet time. 

The speed at which you’ll be able to upload and download files will, of course, be impacted by your internet connection. To make sure this doesn’t affect our findings, we tether download and upload speeds when using each cloud storage service, so they’re all on a level playing field. We also note any problems that arise when internet connection is lost while you’re trying to upload files.

Cloud storage security

You may have understandable concerns about the security of your photos and documents if they’re saved on an online cloud storage service.

When assessing cloud storage services, we check for encryption – which helps keep your personal files private. We also look at whether you’re required or at least encouraged to formulate a long and strong password, plus whether there’s two-factor authentication – for instance, whether you have to type in a code that’s sent via SMS to your smartphone when you try to log into the cloud storage service.

For more information on these tests, head straight to our page on cloud storage services security.

Cloud storage smartphone apps

You may know the feeling of dismay when your smartphone tells you that your storage space has been used up. One way to get around this is to transfer your photos to a cloud storage service.

In our tests, we explore how easy it is to upload and download photos to the cloud, and whether you can sync material when not connected to wi-fi – in case you run out of space while out for the day. We look at this on both iOS and Android operating systems.

Which cloud storage should you use?

80%The score a cloud storage service needs to earn our Best Buy recommendation

All the above tests, and more, are analysed to create an overall test score and recommendation. This helps us separate the best from the worst, so you know which cloud storage service deserves your time and effort.

The total test score is made up of the following factors:

  • 80% ease of use
  • 20% speed

Cloud storage services that earn 80% in our rigorous tests are awarded our Best Buy recommendation.


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