Under resting conditions, total body oxygen consumption is:

Every 100 mL of aerial blood carries approx. 20 mL of oxygen. Of this 20 mL, tissues extract (and utilize) 5 mL, under resting conditions of metabolism. Considering the normal cardiac output (under resting conditions) to be 5 L/min, 250 mL of oxygen will be extracted by the entire body. (5 mL from every 100 mL of blood; 250 mL from 5 L of blood.)