The raw respiration signal has arbitrary units, the mL values are calculated on the TidalVolume and MinuteVentilation only (please refer to this link).
We do a general calibration using the weight and height of the user, but it is not a complete calibration per see. The calculated coefficient is the conversion factor to convert the raw data into an adjusted value in liters. You can change that coefficient to fit any calibration using an API call. We plan to revisit this calibration method. Calibration may require an external device for a real gold standard reference, such as a spirometer.
Keywords: respiratory metrics, conversion factor