Why Is Blood Red? The Incredible Truth


Why is blood red? This is a question that numerous people are curious about.To learn the correct answer to this question, you have first to understand how you perceive colors. Secondly, you have to learn about blood and its related characteristics. The question has to be answered with several explanations.

How do People See Colors?

Colors can be measured optimally through their peak wavelengths. Wavelengths are like ocean waves, they have their peaks and troughs. Some of these lights are visible to the naked eye and are called visible light, while some are non-visible (infrared and ultraviolet).

The color that we perceive is the light reflected by that particular substance in its visible spectrum.Take note that it’s not the light absorbed. Hence, a white colored object that you see would have absorbed all the different colors, while the black object, had reflected all the colors.

What about Blood? Why is Blood Red?


Based on the information above, we can conclude that the color that is reflected by blood is red. This is because it’s the color of its main cell-components.

What are the Main Cells of the Blood?

Blood is made up of three main cells:

1. Red Blood Cells (RBCs)

Around 5 to 6 million cells per cubic millimeter are present in normal adults. The value is slightly higher in men because they have larger body mass. These cells are the essential and primary components of blood because they number by the millions.

The major function of these cells is to transport oxygen and essential nutrients to the different parts of the body. With insufficient RBCs, you would become anemic and this would be life threatening.

2. White Blood Cells (WBCs)

These cells are responsible for the natural immune system of the body and many other physiological functions. The normal value for these cells is 5,000 to 10,000 per cubic millimeter. Examples of WBCs are the granulocytes (neutrophils, eosinophils, and basophils), and the agranulocytes (monocytes and lymphocytes).

3. Platelets (Plts)

These cells are mainly responsible for blood clotting. The normal value for these cells is about 200,000 to 450,000 per cubic millimeter.

Clearly, you can conclude that RBCs are significantly higher in number than any of the blood components. Thus, the color that it reflects, which is red, is the color of blood.

What’s Inside the RBC that Gives off Its Red Color?

But what’s inside the RBC that gives off the red color? We can now delve deeper into the reason why blood is colored red. Inside your RBCs is hemoglobin their primary content. Hemoglobin has heme subunits and a globin portion. The heme is the portion that reflects red light. So, when blood is seen through the naked eye, it looks red because of its large numberof hemes inside the RBCs.

More specifically, the heme subunits contain iron, which when combined with oxygen, reflects red colors. Deoxygenated blood is dark red in color, while oxygenated blood is bright red in color. The deoxygenated blood runs in your veins and the oxygenated blood runs in your arteries.

Nonetheless, your blood vessels may appear blue because of the interaction of the vessels and the skin,which reflects the color blue. Moreover, the veins are actually red or dark red per see when inside the body.

You can watch these videos for more information about why the color of your blood is red.


I have answered the question: Why is blood red? Hopefully, this information could help you understand more the root cause of the red color of your blood. Next time, someone’s blood is of another color, you can suspect that he must be an alien. Sounds funny, but it’s not. It’s based on scientific facts that all human blood must be colored dark red or bright red.

Feel free to share this post with your friends, if you find it informational.


Hello everyone! I’m glad to have you here. I’m a medical technologist by profession. My second love is writing. So, I’m focusing on providing content to help other people with their health problems. I hope I can be of help to you.

Click Here to Leave a Comment Below

Leave a Comment: