Abstract: A system for a wearable device to measure and monitor human body vitals is provided. The wearable device includes a main body and a strap coupled to the main body. The main body includes a first electrode and a second electrode configured to contact the wrist of the user and a third electrode coupled at a top side of the main body. The main body includes a mechanical switch connected at a first position to supply voltage between first electrode and the second electrode to measure a skin impedance using an internal measurement unit. The mechanical switch is connected at a second position to supply voltage between the first electrode and the third electrode to measure full body impedance when a user touches the third electrode with another hand/leg. The processing subsystem calculates multiple human body vitals based on the calculated skin impedance and full body impedance.