How Much Blood Is in the Human Body

As the essential liquid in our body, the state of our blood says a lot about our health. If you’ve ever donated or had your blood drawn, you might’ve wondered how much blood is in the human body.
Well, here you’ll find the information you’re looking for.

We’ll answer a few common questions that people have about blood so that you can have some useful general knowledge about blood.

How Much Blood Do We Have?

The amount of blood in your body can vary according to a few factors. However, the most important factor is the size of the body, which correlates with sex, build, age, etc..

The average adult male has around 12 pints of blood compared to 9 pints for the average adult female. But an adult man and an adult woman who are almost of the same size and weight would have almost the same amount of blood. Pregnant women usually have 30-40% more blood in their body to support the healthy growth of their baby. This amount to another 2.4 to 3.2 pints of blood.

At birth, babies have very little blood. An average newborn weighing between 5-8 pounds only has about 0.4 pints of blood in their body. This is why they often have a blueish skin tone when they’re born.

By the time children are 5-6 years old, they have more volume of blood per pound of body weight than adults. This means that an 80lb child will have more than half the volume of blood of a 160lb adult.

You can find out the amount of blood in your body by taking a blood volume test. It’s commonly used to check for blood disorders such as anemia. Another very common and useful test is the CBC (Complete Blood Count). It measures the makeup of blood which breaks down to the main types of blood cells.

What Is Blood Made Out Of?

As you might imagine, around 45-50% of your blood is an aqueous solution called the blood plasma. The water base contains protein, sugar, salt, and fat. It serves the important role of transporting your blood cells that form inside your bone marrow to the rest of the body. It also transports hormones, proteins, antibodies, and many other cells and chemicals.

As far as blood cells go, there are three main types:

Red blood cells (RBCs), also known as erythrocytes, are so-called for their vibrant red color. RBCs the most abundant, making up around 40-45% of your total blood volume. These blood cells form in the bone marrow, where they mature in around 7 days and are then released into the bloodstream.

RBCs are very flexible but vulnerable, which is why the average life for these cells is around 120 days. Their most important role is the transportation of oxygen from the lungs to the brain and other body parts, thanks to the content of a protein called hemoglobin.

White blood cells (WBCs, leukocytes) make up only around 1% of the total blood volume. WBCs are part of the immune system responsible for fighting off infections and diseases.

There are two main types of white blood cells: granulocytes and lymphocytes. Of the three main types of granulocytes, neutrophil granulocytes account for around 55-70% of all white cells and are the ones that react immediately to an infection. However, they live less than one day, which is why the bone marrow needs to continuously produce them to keep your body free of infections.

Lymphocytes can be divided into T and B lymphocytes. T lymphocytes support your immune system and attack tumors and infected cells. B lymphocytes are in charge of creating antibodies that neutralize pathogens such as viruses, bacteria, and various foreign bodies.

The third type of blood cells is platelets (thrombocytes). They’re not actual cells but rather fragments of cells that help with coagulation (blood clotting). When there’s an injury, platelets gather around the lining of destroyed blood vessels and create a platform where coagulation begins.

If a person has too many platelets, the blood might clot too easily, which can cause heart attacks and strokes. On the other hand, low platelet count can cause excessive bleeding. Luckily, there are treatments for both cases.

How Much Blood Are You Allowed to Donate?

In the US, a blood donor can give up to 1 pint of blood at one time. As a general rule, the amount that a person should donate shouldn’t go over 10-12% of the person’s total blood volume. The time between two donations shouldn’t be shorter than 8 weeks.

If you lose too much blood, you might go into shock. This usually happens when a person loses 20% or more of their blood. When this happens, there’s no way for oxygen to travel through the body, which can cause severe damage to the brain and organs.

The blood pressure would lower, the body’s mechanism to prevent the blood from flowing out of the body. The heart rate would speed up to increase blood circulation to all vital organs. Blood loss of over 40% is lethal.

Donating blood is a very noble thing to do. In the US, it’s estimated that a person needs a blood transfusion every 2 seconds. Less than 38% of the US population is eligible to give blood, and there’s no other way of getting blood to those that need it.

A single donation might be able to save three lives, so you can help a lot of people survive serious health conditions if you donate regularly.

Check Your Blood

It’s recommended to get a routine blood test every once in a while, even if you don’t feel sick. A CBC can show you the current state of your blood and your attending doctor would be able to see if there are any threats and lifestyle choices that you have to make. You may want to do this once or twice a year just to make sure everything is in order.

Now that you know how much blood is in the human body, as well as some basic information on what it’s made of, you can see if you’re eligible to give blood to those who might be in need. If everybody thinks in this fashion, you wouldn’t run out of blood if you need it one day yourself.