What is the normal adult respiratory rate at rest?

• A. 8 to 12 breaths per minute
• B. 12 to 20 breaths per minute
• C. 20 to 30 breaths per minute
• D. 10 to 14 breaths per minute

Answer: (D)

Normal adult resting breathing is about 12 to 20 breaths per minute. This range is the standard reference for a quiet, at-rest state and reflects normal respiratory control in healthy adults. The given range of 12-20 fits this, while 8-12 is typically considered low and may indicate bradypnea in some situations, 20-30 suggests tachypnea from fever, anxiety, or illness, and 10-14 is narrower and not the commonly cited standard for resting rate. So the range that best represents normal resting ventilation is 12 to 20 breaths per minute.