The cardiac output is the amount of blood that your heart pumps out in Liter per minute. To find out what your cardiac output is, take your heart rate (how many times your heart beats in a minute) and multiply it by the stroke volume (the amount of blood in each pump). Most people don’t know their stroke volume. You would have to go ask your doctor about that. It is easy to check your heart rate though. Most people’s resting heart rate is around 70 beats per minute. An average stroke volume is about 70 mL per beat. If you multiply those two numbers you get the average resting cardiac output:
70 (beats/min) X 70 (mL/beat) = 4900 mL/minute
The average person has around 5 liters of blood, so that means at rest the cardiac output is about the entire volume of your blood. If you are exercising that can increase up to 7 fold.