The present invention relates to an improved non-invasive sphygmomanometer which is able to calculate the quality of a blood pressure reading and display quality information to the user. More specifically the invention relates to a sphygmomanometer and the use of oscillometric readings to calculate the quality of the readings, and a quality indicator device for use with the same. The invention uses the identified relationship between the waveform quality from recorded oscillometric pulses and blood pressure (BP) measurement error.
