How accurate is the hydration tracking?

Across the reviewers we read, accuracy is the single biggest pain point. Manufacturer specs (e.g. WaterH's BOOST claims roughly 15% tolerance) hinge on holding the bottle in a narrow angle range and sipping consistently — community threads report that real-world tracking drifts noticeably outside those conditions. Reddit users in r/HidrateSpark and r/HydroHomies generally say the trackers are 'directionally correct' rather than precise.