What is the normal adult respiratory rate range?

• A. 8 to 12 breaths per minute
• B. 12 to 20 breaths per minute
• C. 20 to 24 breaths per minute
• D. 14 to 22 breaths per minute

Answer: (B)

Normal adult resting breathing runs about 12 to 20 breaths per minute. This range reflects the typical quiet, at-rest rate for a healthy adult. Breathing significantly slower, around 8–12, can indicate bradypnea, which may occur with fatigue, drug effects, or high athletic conditioning. Breathing faster, especially 20–24 or more, points to tachypnea, which can happen with fever, anxiety, hypoxia, or metabolic stress. The standard reference interval used clinically and in exams is 12–20, so that range is the best descriptor of normal resting respiration. The other options fall outside the usual resting interval and are not the typical baseline values.