When the Apple Watch is paired with an iPhone, all data is stored on the iPhone. You don’t need to back up your data manually, or set up a backup plan. As long as your iPhone and Apple Watch are close, all your data will sync between the two devices, and only the iPhone will save data when connected to Wi-Fi.
Apple also creates a backup of your Apple Watch data when you transfer it from your iPhone. This allows you to set up a new Apple Watch or restore your existing one using just your iPhone.
When your iPhone is backed up to iCloud, your Apple Watch data is also included. As a result, when you set up a new iPhone, your Apple Watch data is reset. Apple Watch information is also included when you sync your iPhone to a computer.
It’s important to note that this only works for Apple Watches that are based on the iPhone. If you set up a family member’s Apple Watch without an iPhone, such as a child’s Apple Watch, their data is saved to their iCloud account. This happens automatically when the Apple Watch is charging and connected to Wi-Fi. Here’s how to make sure iCloud backup is turned on on a family-run Apple Watch:
Open the Settings app on your Apple Watch.
Click the account name above.
Make sure that “iCloud backup” is turned on.