All-Day Battery Life Tips for Apple Watch

If you're using an Apple Watch Series 7 or earlier, the biggest tip here is to keep your phone on you. The Apple Watch is smart and will use your phone's GPS if it is nearby and you have Bluetooth on, which saves your Watch's battery and lets it focus on running the heart rate sensor. Using your Watch's GPS alone you can expect ~6hrs of battery life, but with your phone on you you'll see all-day battery life.

As of Series 8, the second generation SE and Apple Watch Ultra, the newest models do not piggyback off the iPhone's GPS though, so taking your phone with you will make no difference as they will use the built-in Apple Watch GPS even when your iPhone is nearby.