What is the normal adult respiratory rate?

• A. 8-12 breaths per minute
• B. 15-25 breaths per minute
• C. 20-30 breaths per minute
• D. 12-20 breaths per minute

Answer: (D)

Normal adult resting respiratory rate is 12–20 breaths per minute. This range is a standard vital sign that reflects quiet, at-rest breathing and the body's balance of oxygen intake and carbon dioxide elimination. Rates outside this window can indicate issues: slower breathing may signal bradypnea or CNS depression, while faster breathing—tachypnea—can accompany fever, anxiety, hypoxia, or respiratory illness. The 12–20 range matches the typical reference for a healthy adult at rest, making it the best choice. The other ranges are either below or above what's considered normal for a resting adult.