Do I need my phone when I use my Apple Watch?
If you have a newer Apple Watch, there is no need to take your iPhone with you.
Starting with Series 8, the second-generation SE, and Apple Watch Ultra, these models have built-in GPS and no longer rely on your iPhone’s GPS, even if it’s nearby. That means you’ll still get accurate tracking and data, and everything will sync automatically once your watch reconnects to your phone.
If you are using a Series 7 or older, we recommend taking your iPhone with you. For these models, the Apple Watch will use the iPhone's GPS instead of its own when it can, which will improve data accuracy and battery life.