Approximately how much air does a healthy adult at rest inhale per breath?

Approximately how much air does a healthy adult at rest inhale per breath?

• A. 250 ml
• B. 750 ml
• C. 500 ml
• D. 1000 ml

Answer: (C)

The main idea here is tidal volume—the amount of air moved in and out with each normal breath during quiet breathing. In a healthy adult at rest, this breath volume is about half a liter, commonly described as five hundred milliliters per breath. That amount represents the air that actually reaches the gas‑exchange surfaces in the lungs during calm breathing. A portion of the inhaled air fills the conducting airways and doesn’t participate in gas exchange (dead space), but the typical resting tidal volume sits around this half‑liter mark. The other amounts listed would correspond to shallower breathing or deeper breathing than is usual at rest.

The main idea here is tidal volume—the amount of air moved in and out with each normal breath during quiet breathing. In a healthy adult at rest, this breath volume is about half a liter, commonly described as five hundred milliliters per breath. That amount represents the air that actually reaches the gas‑exchange surfaces in the lungs during calm breathing. A portion of the inhaled air fills the conducting airways and doesn’t participate in gas exchange (dead space), but the typical resting tidal volume sits around this half‑liter mark. The other amounts listed would correspond to shallower breathing or deeper breathing than is usual at rest.