The amount of blood in a body varies slightly with size, sex and age, but the average human has 8-12 pints of blood in their body. A blood loss of 4 pints or more without immediate medical attention will usually prove fatal.
The estimated volume of blood in the human body is about 7% of your body weight. An average adult weighing 150 to 180 pounds will have 4 - 5 liters or 1.2 to 1 1/2 gallons of blood, equal to about 5 quarts.
8-12 pints depending on the size of the person. Actually about 5 litre of blood is present in a normal human body It varies by age and weight, but the "standard" answer is 6 liters, or about a gallon and a half.