What is the normal respiratory rate range for an adult?

• A. 8-12 breaths per minute
• B. 20-30 breaths per minute
• C. 12-20 breaths per minute
• D. 25-40 breaths per minute

Answer: (C)

The main idea is that a healthy adult at rest breathes about 12 to 20 times per minute. This range reflects normal control of breathing by the brain in response to carbon dioxide levels in the blood; when CO2 rises, breathing speeds up to get rid of it, and when CO2 falls, breathing slows down. Among the options, 12 to 20 fits the typical resting rate for most adults. The other ranges are outside the normal resting window: 8–12 sits at the lower end and can indicate bradypnea or simply a very relaxed state in some individuals, while 20–30 and 25–40 indicate tachypnea, which you’d expect with fever, stress, anxiety, overexertion, or respiratory problems. If a person’s rate consistently falls outside the 12–20 range while at rest, it warrants evaluation for underlying conditions.