Many cervical collars have an adjustable circumference and you only need to consider the proper height. This is measured from the base of the shoulder to the chin. You can easily do that just by using your hand: look at the patient's neck from the side and place your outstretched hand on their shoulder, with the pinky finger down. Count the fingers from the shoulder to where the imaginary line of their chin meets your hand. If the measurement falls between two cervical collar heights, choose the smaller one. If you also need to measure the neck circumference, do so with a measuring tape just below the patient's Adam's apple.