A device and method for determining the hydration and water content status of soft biological tissue is disclosed and includes a couple of ultrasonic transducers located at a known distance therebetween and held against the tissue of interest as well as an adjustable support system with angle measuring means necessary for evaluation of ultrasound velocity in this tissue. Based on the time-of-flight results of the ultrasound velocity measurement, the water content in the tested tissue is evaluated and the hydration status is determined. One embodiment of the invention is a wearable device attached to human calf measuring water content in muscle.