People replacing or resetting a phone
Check which photos, messages, app data and settings are in your backup, and which will move only during setup. Keep access to the relevant account and old phone until you have checked the new one.
Who needs to plan a backup?
Windows and Mac users protecting personal files
Photos, documents and videos need a copy separate from the computer being replaced or repaired. Choose a destination with enough space and check that your intended backup tool can use it.
People with large photo or video collections
Compare the size of the files you intend to keep with your cloud allowance or drive capacity. Consider how you will access the copy later, rather than choosing a device solely by its stated capacity.
What should you check before choosing?
Start with what must survive the loss or erasure of the old device, then check capacity and the steps needed to restore those files.
| Priority | What to check | Your needs |
|---|---|---|
| A separate copy | Identify where the copy will be stored and how you would retrieve it without the old device. The National Cyber Security Centre defines a backup as a copy kept in a separate safe location; a setup transfer alone does not establish that you have one. | I want my photos and documents to remain accessible if the old device is erased, lost or unavailable. |
| Enough space | Compare the file set and existing account use with the destination capacity. Apple Support lists 5 GB of free iCloud storage; Google One Help says a standard Google Account has up to 15 GB shared across Gmail, Drive and Photos; Microsoft Support lists 5 GB of free Microsoft cloud storage. | My files and existing cloud use need to fit before I rely on another backup completing. |
| Backup contents | Check the selected folders, synchronised data and app-specific content, then open sample files or check a restore. Apple Support distinguishes iCloud-synchronised information from iCloud Backup; Google Android Help says restoration varies by phone and Android version. | I need to know whether the particular messages, downloads, photos or app data I care about will come across. |
| Device compatibility | Confirm the account, operating system, connection and backup tool needed at both ends. For Time Machine, Apple Support recommends a disk with at least twice the Mac’s storage capacity and says it cannot back up to a Windows-formatted disk without reformatting. | A drive or transfer method needs to work with my current device and the one on which I may restore the files. |
| Transfer method | Decide whether you need an ongoing backup or a selected-file transfer. Which? distinguishes HDDs for long-term computer-file backup from generally faster SSDs, while its USB-stick guidance describes moving files between computers. | If I am moving only selected documents, a portable file copy may suffice; before a reset, I also need a separate copy of anything I cannot replace. |
What can go wrong before a reset?
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Assuming a completed transfer includes everything
Apple Support treats iCloud-synchronised data separately from iCloud Backup, and Google Android Help identifies content that may not copy in an Android setup transfer. A successful setup screen is not a check of every valued file.
List the photos, downloads, messages and app data you need. Check where each is stored and open representative files on the destination before erasing the original.
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Starting a cloud backup without checking space
Cloud allowances may be shared with other services. For example, Google Account storage covers Gmail, Drive and Photos, so the allowance is not necessarily all available for a new backup.
Check current usage and the size of the intended backup, then confirm it has completed before proceeding with the replacement.
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Using an unsuitable local drive
A drive needs sufficient capacity, a usable connection and a format accepted by the backup tool. Apple Support says Time Machine cannot back up to a Windows-formatted disk.
Check the drive, cable and formatting requirements before copying. Move any existing files elsewhere before reformatting a disk, because formatting can erase them.
Changing a drive’s format can also mean moving its existing files and setting up the backup again.
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Letting the old device go too soon
If the new device has not been checked, missing files or an incomplete restoration can be harder to address once the original is unavailable. Apple Support specifically says not to erase an old iPhone or iPad until restoration from temporary iCloud storage is complete.
Keep the old device, backup medium and account credentials available until you have signed in and checked important files and app data on the replacement.
Which platform guidance matters?
Start with the backup and restoration tools for your device; a drive brand alone cannot tell you what your operating system will include.
Apple
Relevant to iCloud and computer backups for iPhone and iPad, and Time Machine backups for Mac.
- Apple Support distinguishes data synchronised to iCloud from information stored in iCloud Backup and lists 5 GB of free iCloud storage.
- For Time Machine, Apple Support recommends a disk with at least twice the Mac’s storage capacity; a Windows-formatted disk may require erasing and reformatting.
Relevant to Android backup, Google Account storage and migration to another Android phone.
- Google One Help lists up to 15 GB with a standard Google Account, shared across Gmail, Drive and Photos.
- Google Android Help says restoration varies by phone and Android version, and its described setup transfer does not copy every data category.
Microsoft
Relevant to Windows Backup and OneDrive for account-based copies, or File History for recurring local copies.
- Microsoft Support describes File History backups to an external drive or network location and lists 5 GB of free Microsoft cloud storage.
- Check which folders and settings your chosen Windows method includes before relying on it for a replacement PC.
Seagate
An external-drive brand included in the UK portable-storage context covered by Which?; choose by the specifications of the individual drive.
- An external drive can provide a separate destination for selected computer files when its capacity and connection suit the task.
- Check the exact model’s connector, capacity and suitability for your backup software rather than assuming all drives in a brand’s range work alike.
Western Digital
An external-drive brand included in the UK portable-storage context covered by Which?; the individual model determines the practical fit.
- Which? distinguishes the long-term computer-backup use of HDDs from the generally faster transfer speeds of SSDs at category level.
- Confirm capacity, connection and operating-system requirements for the particular drive before making it your backup destination.
External drives for a separate file copy
These Joybuy options are external SSDs and HDDs for keeping personal files on a separate drive. Compare their stated capacity and connection with your devices, then check how you will copy and retrieve the files; a drive by itself does not complete a backup.
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Samsung MU-PE1T0S 1TB USB Type-C SSD
For a separate copy of selected files, compare the stated 1TB capacity with the files you need to keep. The title specifies USB Type-C 3.2 Gen 2; check your device’s connection and backup method, then open copied files before erasing the original.
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Samsung Portable SSD T7 4 TB Grey
This external SSD offers a stated 4 TB destination for a larger selected file collection. Its title specifies USB Type-C 3.2 Gen 2; check the connection and your backup software’s requirements before depending on it for restoration.
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Western Digital Elements Port. 4TB USB 3.0
For a local copy of computer files, this external HDD has a stated 4TB capacity and USB 3.0 in its title. Check the connection and required disk format for your computer, particularly if you intend to use Mac backup software.
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SanDisk Portable SSD 2TB
This external SSD provides a stated 2TB destination for files you want to keep apart from the old device. Check the connector, cable and operating-system compatibility against your devices before choosing how to make the copy.
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Western Digital My Passport Ultra for Mac 5TB
This 5TB external HDD is identified as a Mac variant for storing a separate file collection. Check its format against your chosen Mac backup tool, and confirm the setup needed if you also intend to use it with another operating system.
Questions before replacing your device
Is transferring files to a new device the same as making a backup?
No. The National Cyber Security Centre defines a backup as a copy kept in a separate safe location. A direct transfer helps move supported content during setup, but check or make a separate, restorable copy before resetting or giving up the old device.
What should I check before erasing an old iPhone or iPad?
Confirm which iCloud or computer backup you intend to restore, then check important data on the new device. Apple Support says an encrypted computer backup is needed to transfer Health and Activity data, and specifically advises against erasing the old device before restoration from temporary iCloud storage is complete.
What might not move to a new Android phone?
It varies by device and Android version. Google Android Help identifies downloads, media in hidden folders, apps outside Google Play and some account or app data among items that do not copy in its described setup flow. Review those categories and copy important files separately before retiring the old phone.
Can I use a Windows-formatted drive for Time Machine?
Not without changing its format: Apple Support says Time Machine cannot back up to a Windows-formatted disk. Check the required Mac format and move existing files to another location before reformatting, which can erase what is already on the drive.