The day you need a backup is the day you cannot make one. Phones are stolen, they fall in water, and they stop charging without warning. Twenty minutes now is the whole job.
Contacts: save them to the account, not the phone
A contact saved to the SIM or to the phone itself dies with the phone. A contact saved to your Google or iCloud account follows you to the next one.
On Android: open Settings, then Google, then Backup, and make sure backup is on. Then open Contacts, go to Settings inside the app, and look for Default account for new contacts. Set it to your Gmail address. While you are there, use Import or Move device contacts to pull anything sitting on the SIM or the phone into the Google account.
On iPhone: Settings, tap your name at the top, then iCloud, and switch Contacts on.
To check it worked, open Gmail on any computer and look at Google Contacts. If your people are there, they are safe.
Photos: pick one place and let it run
Google Photos is the usual answer on Android and works on iPhone too. Open it, tap your picture in the corner, go to Photos settings, then Backup, and turn it on.
Two settings decide whether this costs you money or bundle:
- Backup quality. Choose Storage saver rather than Original quality. The difference is invisible on a phone screen and it stretches your free 15GB much further.
- Mobile data usage. Set photos and videos to back up over Wi-Fi only, unless you genuinely want to spend bundle on it.
Google gives every account 15GB free, shared between Photos, Gmail and Drive. That is enough for years of phone photos on Storage saver, and nowhere near enough for a lot of video.
On iPhone, Settings, your name, iCloud, Photos, and switch on Sync this iPhone. Apple gives you 5GB free, which fills quickly. Many people back up to Google Photos on an iPhone for exactly that reason.
The offline copy
Cloud backup fails in one specific way: you lose the password, or the account is hijacked. A copy you hold yourself covers that.
Once or twice a year, plug the phone into a computer with a cable and drag the DCIM folder onto the computer or an external drive. On an iPhone you may need to set Settings, Photos, Transfer to Mac or PC to Keep Originals first.
Check it, do not trust it
A backup nobody has tested is a rumour. Open Google Photos on a computer, sign in, and confirm last week's pictures are there. Do the same for contacts. Do this once every few months.
The WhatsApp exception
WhatsApp does not back up to Google Photos. It has its own: Settings, Chats, Chat backup. Set it to back up daily to Google Drive on Android, or to iCloud on iPhone. Without it, changing phones loses every conversation.