How Much Blood Is in the Human Body?

11/24/2021 | 5 min. read

Healthy Directions Staff Editor

Healthy Directions Staff Editor

So, how much blood do you have in your body? That question is easy enough to answer: approximately 10 pints, or just over a gallon.

But here’s the thing: you might have come looking for a simple answer like this, or you might have been hoping for a few more details. There are lots of different people who would need this question answered.

Writers often go to medical sites to see how the human body would fare against the latest sci-fi creature they’ve cooked up in their thriller novel. Perhaps a cautious blood donor would look up how much blood they can give before it becomes unhealthy for themselves.

Or you might just be a connoisseur of curiosity and learning about new things. If you find yourself falling under any of these categories, then stick around because we’ve got a few more “juicy” details for you.

What’s In Our Blood?

First it’s good to learn what makes our blood tick. Metaphorically speaking, of course. What literally makes our blood tick is our heart.

We call these ticks heartbeats, of course, and with each beat, our hearts pump roughly a third of a cup of blood, around 100,000 times a day. That’s approximately 6,000 liters or 1,500 gallons of blood.

A perfectly intact human body will always have around 10 pints of blood within it, constantly being circulated. However, if it was being produced rather than circulated, this is how much blood we would be making.

The volume is enough to fill 30 bathtubs each day, give or take.

Another thing to understand is that blood contains a lot of other components. The human body is made up of 70% water, as you may know. But the approximate 8% of the body that blood occupies has parts of its own.

The four main parts are known as red cells, white cells, platelets, and plasma.

The plasma makes up 54% of blood, red blood cells are at 45%, and the white blood cells and platelets put together only make up about 1% of our blood’s structure. On top of these components, blood is used to transport vital nutrients throughout the whole body.

Because of all these important facets in our blood, it is indeed thicker than water. At least physically thicker. However, the 70% water and 8% blood that resides within us share the same density.

The difference in density is subtle compared to the apparent difference in physical interaction and behavior. If you were to weigh a cup of blood and water, you would find that they are more or less the same.

How Much Blood Do I Need?

Now, particularly for those writers out there, you might be curious how much blood your body needs to keep everything up and running--and how much it can lose.

This is why, as always, it’s good to consult a specialist to see how much you can donate.

This should in no way scare anyone out of giving blood. All around the world, there are constantly people in need of blood due to an accident or a physical condition that prevents them from producing the amount or type of blood they need.

As for blood type, there are 8: A, B, AB, O, and the negative versions of all these.

O positive is the most common, but if your blood type is AB, you have more reason to see if you can donate because this is one of the rarest blood types.

The human body, as we now know, contains about 10 pints of blood at all times. This means that the ideal condition for us is about 10 pints.

Generally speaking, you can lose under 40% of your blood and still live.

However, as you start to cross that line, you step closer to fainting and, eventually, death. Even under 40%, the less blood in your system, providing all of those essential sugars and oxygen, the more likely you are to become dizzy or sleepy.

Most movies teach us that the most important thing to do while wounded is to stop the bleeding somehow, and that much is true. Taking a blade or shrapnel out of the body is something to avoid since while it is embedded in the body, it is at least serving as a clot for the blood.

What Are Some Tips For Donating?

Since our blood is so necessary, any nurse treating you while you donate blood will ensure that you don’t give enough to harm yourself. They will also ask certain questions to make sure donating is safe for both you and the eventual recipient.

And as it was said before, it never hurts to ask a doctor if you are approved for donating. Your body type can make you more prone to passing out than others, but some medical histories may prevent you from donating entirely.

Most donation sites try to set a limit for each donor, and it usually revolves around the maximum of one pint. Those who are specifically donating platelets will most likely give in lower quantities since our blood naturally contains less of these components.

Healthy donors can always give again, and there’s always someone in constant need of donated blood in order to survive, but donations should usually be spaced out between a couple of months’ time, so your body has a chance to recuperate.

Takeaway

That concludes how much blood our bodies contain and need and what happens when these amounts are affected somehow.

Hopefully, you can apply this information to treat your body with the care it deserves--or at least be more accurate when describing how much blood your poor character has lost.

To learn more, click here for more information.

Sources:

50 Quick Blood Facts | American Red Cross

Composition of Blood | Advanced

Physiology, Blood Volume | NCBI

Healthy Directions Staff Editor