Question: how many liters of blood does human have?
Answer: The average adult has about 1.2 to 1.5 gallons (4.5 to 5.5 liters) of blood circulating inside their body, said Dr. Daniel Landau, a hematologist and oncologist at the University of Florida Cancer Center – Orlando Health. By the time they're 5 or 6 years old, children have about the same amount of blood as adults do.