Kubios HRV app has this parameter also. Unlike @yokuha, I can’t see any short term correlation from about one year of daily data. I do see long term trends that correlate with what I’m feeling.
Kubios uses the Square of the Baevsky calculated number and considers 7-12 as normal
https://www.kubios.com/hrv-analysis-methods/
There is not a lot of info on the metric but I did find an article where the following numbers were noted:
- lower then 10: Low Stress
- 10-15 Normal
- higher then 15: High stress
Something more detailed but in German:
https://hrv-herzratenvariabilität.de/2020/03/berechnung-des-hrv-stressindex-nach-baevsky/