Average adult respiratory rate: 12–20 breaths/minute (typically 12–15 at rest).
Daily estimate: 12 breaths/min × 60 min × 24 hr = 17,280 breaths/day (range ~17,000–30,000). Rate increases with exercise, stress, fever, illness; decreases during sleep, relaxation. Tidal volume (~500 mL) × rate = minute ventilation (~6 L/min at rest).