Balance score
The Balance score is a measure that, from the heartbeat fluctuations (HRV) your Apple Watch reads, estimates how well-balanced your autonomic nervous system is and shows it continuously on a 0–100 scale. It doesn't try to guess your mood or emotions. Instead, it's a gentle yardstick that reflects how settled or unsettled your body is right now.
What's Inside the Score
- The measurement starts from HRV (Heart Rate Variability) — the tiny fluctuations in the interval between one heartbeat and the next (the R-R interval). The size and pattern of these fluctuations mirror how your autonomic nervous system is working.
- The Balance score is not made from one public metric or a simple ratio. It summarizes multiple HRV-derived clues, measurement quality, and movement from your own baseline on device.
- The exact composition, weighting, and conversion method are Feelmo's proprietary analysis logic and are not disclosed publicly.
- The lower it is, the more "unsettled" your state; the higher it is, the more "settled."
- The Balance score also estimates its own confidence. On a night it couldn't measure you well and can't be sure, rather than forcing out a shaky number it may show a wider range, or hold the display back for now. A day with no number isn't a malfunction.
One number, many clues
The Balance score is not a direct display of any single HRV metric. It translates multiple clues into a form that is easier to read day by day, always against your own usual baseline. For the broader science of HRV, see About HRV.
How to Read It
The Balance score is most meaningful when you read it as the difference from your usual self, rather than as an absolute value.
| State | Guideline |
|---|---|
| Settled | Your score is higher than your baseline and stable |
| Ordinary | Around your baseline |
| Unsettled | Lower than your baseline, or swinging widely |
Don't compare with others
HRV varies a lot from person to person depending on constitution, age, and measurement conditions, so comparing your numbers with someone else's doesn't mean much. What matters is the difference from your own baseline. Rather than the number itself, watch which way you've moved away from your "usual self."
Why "Balance" Instead of "Emotion"
Even with the very same heartbeat fluctuation, a "joyful rush" and an "anxious rush" look very similar at the level of the body. That's why Feelmo does not declare from HRV whether a feeling is good or bad (its valence). Instead, it quietly reflects only balance — the judgment-free sense of being "settled or unsettled." Watching over how settled you are — rather than guessing your feelings — is Feelmo's principle.
Faces, Not Just a Score
Rather than putting the number front and center, Feelmo translates it into the nearest of the six faces and sets it gently beside you each day. "Lively, Calm, Ordinary, Anxious, Overloaded, Tired" — the score works in the background of those faces.
Measuring Well
- The Balance score grows from HRV that your Apple Watch measures during sleep. Wrist measurement is sensitive to body movement, so a still measurement during sleep is the most stable (Connecting with Apple Watch).
- Once a few days of records accumulate, your baseline takes shape, and the differences in your score become easier to read.
Go deeper
For the scientific background with sources, head to The Science of Balance. For common misunderstandings, see Unraveling Misconceptions.
Important
The Balance score is a hint about trends in your physical condition and autonomic nervous system — it does not perform medical diagnosis, treatment, or any judgment of your health status. Feelmo is not a medical device. If you have symptoms that concern you, please consult a medical professional.