Cardiac output is defined as the volume of blood pumped every minute by each (left or right) ventricle of the heart. It is generally reported in L/min or mL/min.
Cardiac output (CO) is the product of heart rate (HR) and stroke volume (SV). Thus,
CO = HR × SV
Heart rate is defined as the number of heart contractions per minute. Stroke volume is the volume of blood pumped per ventricular contraction.
For a typical resting adult human being at rest, CO is approximately 5 L/min.
CO = 70 contractions/min × 70 mL/contraction = 4,900 mL/min