Inexperienced rescuers may encounter severe problems in an unconscious patient with opening and maintaining a patent upper airway. Designing a ventilating device that could indicate how to open an upper airway correctly may be beneficial. The heads of 102 volunteers were randomly placed in different head positions by one investigator. A pocket mask was then pressed gently on the volunteer's face followed by measurement of the head position angles. Mean (SD) flexion was − 4° (8°) (95% CI − 5.9 to − 2.9); the mean neutral position was 21° (6°) (95% CI, 19.9 to 22.3); extension was 42° (6°) (95% CI 40.8 to 43.0°) and differed significantly between each position (p < 0.001). The flexion and neutral position angles were significantly greater in men than in women: − 2 (7°) vs. −8 (7°) and 22 (7°) vs 20 (5°); p < 0.001 and p = 0.03, respectively. Maximum extension of the head in both supine men and women was 42°, which could be utilised to optimise assisted ventilation of an unprotected upper airway.