What Is the Normal Blood Volume Percentage in Humans
The volume of blood in an individual’s body vary from one individual to another. There are lots of factors upon which the blood percentage in the human body depends. Age and size are the two main factors.
The total volume of blood in the human body in litres normally ranges from 4.5 to 5.7 liters. The average blood percentage in the human body is approximately 7 per cent of the body weight. In this article, we’ll discuss the quantity and normal blood percentage in the human body, along with shocks and blood loss.
Average Blood in Human Body in Liters
(Image Will be Updated Soon)
The total blood volume is different in the case of infants, children, and adults. Pregnant women have a different blood percentage in the human body when compared to normal adults. In this part, we will look into total blood in the human body in liters in detail. We will be discussing blood volume. As stated above, the normal blood percentage in the human body is about 7 percent of the body weight.
Infants or babies have approximately 75ml of blood per kilogram of their body weight. So if an infant weighs around 8 pounds, he/she will have approximately 270 ml of blood. An average child weighs around 80 pounds. The blood volume in the child’s body is supposed to be around 2.65 liters of blood. For an average adult, the quantity of blood in the human body in litres is estimated to be around 4.5 to 5.7 litres. Pregnant women have a considerable high blood volume to support the growing baby. It's about 30 to 50 percent greater than a normal adult female. It can be seen that the total blood volume varies with age, sex, and body weight.
Blood Volume Test
This is a test used to determine the volume of blood in the human body in litres and track the movement of the blood cells. It generally tests the blood volume in a human body. In this test, a small tracer element is injected into the bloodstream. The medical professional uses various imaging techniques to trace the movements of the blood cells and measure the average blood in the human body in litres. This test is often recommended by the doctors if the patient shows congestive heart or kidney failure or shocks.
Blood Loss and Shock
The term ‘“shock” can be used to denote a medical condition where sufficient oxygen does not reach every part of the body. Severe states of shock can prove to be quite fatal. Nominal blood loss may not be much of a harm. However, after losing 20-40 percent of the total blood volume, the person will start to feel anxious. The blood pressure will rise rapidly. When the blood loss exceeds the 40 percent mark, the person will feel lethargic and lose consciousness. The person will also experience severe shocks during this time. Blood loss may be due to internal or external bleeding.
The quantity of blood in the human body in litres is around 4.5 litres in the case of an adult. So one can donate up to one pint of blood. As a huge volume of blood is produced, the body can easily replace a small amount of lost or donated blood.
Maintenance and Production of Blood
The human body produces around 2 million red blood cells per second from the stem cells in the bone marrow. These stem cells produce RBCs and maintain the normal blood percentage in the human body. Apart from the RBCs, the white blood cells (WBCs) act as a defence mechanism of the body and platelets. The circulation and purification of the blood are carried out by the various cardiovascular systems. Plasma is an important component of the blood as it carries the RBCs, platelets and boosts the immune system.
Interesting Facts about Total Blood Volume in the Human Body
An adult body has 1,00,000 kilometres or 60,000 miles of blood vessels running throughout the body.
Blood plasma makes up around 55% of the total volume of blood present in the human body.
The average volume of blood present in an adult male body is 5.6 litres, while an adult female body contains 4.5 litres of blood.
FAQs on Blood Percentage in the Human Body and Its Significance
1. What percentage of the human body is made up of blood?
About 7–8% of total body weight in an adult human is made up of blood. In an average adult weighing 70 kg, this equals roughly 4.5–5.5 liters of blood. The exact blood percentage in the human body can vary depending on:
- Age (newborns have a slightly higher percentage)
- Sex (males generally have slightly more blood volume than females)
- Body size and composition
2. How many liters of blood are in the human body?
An average adult human has about 4.5 to 6 liters of blood circulating in the body. Blood volume depends mainly on body weight and height. For example:
- Adult males: around 5–6 liters
- Adult females: around 4–5 liters
- Newborns: about 250–300 milliliters
This total blood volume supports oxygen transport, nutrient delivery, and waste removal.
3. What is blood made up of in the human body?
Blood is composed of plasma and formed elements (blood cells). Its main components include:
- Plasma (55%) – a yellowish fluid containing water, proteins, hormones, and nutrients
- Red blood cells (RBCs) – carry oxygen using hemoglobin
- White blood cells (WBCs) – defend against infection
- Platelets – help in blood clotting
This composition allows blood to perform transport, protection, and regulatory functions.
4. Does blood percentage differ between males and females?
Yes, males generally have a slightly higher blood volume and percentage than females. This difference is mainly due to:
- Greater average body mass in males
- Higher levels of testosterone, which stimulate red blood cell production
- Differences in hematocrit (percentage of RBCs in blood)
As a result, males often have a slightly higher total blood percentage in the human body compared to females.
5. What is hematocrit and how is it related to blood percentage?
Hematocrit is the percentage of blood volume occupied by red blood cells. In healthy adults, normal hematocrit values are:
- Men: about 40–54%
- Women: about 36–48%
Hematocrit reflects the proportion of RBCs in total blood and is an important indicator of anemia, dehydration, or other blood disorders.
6. Why is blood important in the human body?
Blood is essential because it transports oxygen, nutrients, hormones, and removes waste products from the body. Its main functions include:
- Transportation – carries oxygen (via hemoglobin) and nutrients
- Protection – white blood cells fight infections
- Clotting – platelets prevent blood loss
- Regulation – maintains body temperature and pH balance
Without adequate blood volume, tissues cannot receive enough oxygen to survive.
7. How does blood volume change with age?
Blood volume changes with age, with newborns having a higher blood volume per body weight than adults. For example:
- Newborns: about 8–9% of body weight
- Adults: about 7–8% of body weight
As the body grows, total blood volume increases, but the percentage relative to body weight slightly decreases.
8. What happens if the body loses too much blood?
Losing a large percentage of blood can lead to hypovolemic shock, a life-threatening condition. Effects depend on the amount lost:
- Up to 15% loss: usually mild symptoms
- 15–30% loss: rapid heartbeat and weakness
- More than 40% loss: severe shock and possible organ failure
Significant blood loss reduces oxygen supply to tissues and requires immediate medical treatment.
9. Is blood considered a tissue in the human body?
Yes, blood is classified as a connective tissue because it consists of cells suspended in a fluid matrix called plasma. Like other connective tissues, blood:
- Has specialized cells (RBCs, WBCs, platelets)
- Contains an extracellular matrix (plasma)
- Connects and supports body systems through transport
This classification highlights its structural and functional role in the circulatory system.
10. How is blood percentage measured in the human body?
Blood percentage and volume are estimated using body weight calculations and laboratory tests like hematocrit measurement. Common methods include:
- Estimating total blood volume as 7–8% of body weight
- Measuring hematocrit through a blood test
- Using medical imaging or dilution techniques in hospitals
These methods help assess overall blood percentage in the human body and detect abnormalities.
