What your Apple Watch measures — and what it quietly leaves out
Apple Watch is an excellent sensor and a conservative interpreter. It records a great deal and concludes very little, which is why so many questions about it start with “why can’t it just tell me…”. This section works through those gaps one at a time.
Built into watchOS
- Heart rate, resting heart rate and heart rate variability
- Sleep duration and stages
- Activity rings, workouts and, in newer versions, Training Load
- Screen Time — tracked, but kept separate from health
Not built in — needs an app
- A single energy or readiness score (Garmin calls it Body Battery)
- A read on how you are doing right now, rather than raw charts
- Screen use counted as part of your state, not as a separate report
In this section
Body Battery
Why watchOS has no Body Battery, what Apple Watch actually measures, and how the four energy scores compare.