> For the complete documentation index, see [llms.txt](https://docs.tryterra.co/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.tryterra.co/faq/help-topics/data-api-sdk/provider-coverage-and-per-provider-data-availability/fitbit-rr-interval-not-exposed.md).

# Is rr\_interval\_ms available for Fitbit?

Fitbit does not expose raw inter-beat (RR) intervals through its HRV endpoint; it returns low-to-high frequency band ranges rather than IBI values directly, so `rr_interval_ms` is **unavailable for Fitbit**.

Apple, by contrast, does provide beat-to-beat data.