Blood type chart and how to do blood type test

Blood typing is one of the cheapest and easiest tests to carry out. However, many people don't know their blood type. Are you ready to find out your blood type and check for its compatibility using the blood type chart?

Lab scientist taking a patient's blood sample for a blood typing test

Key Takeaways:

  • The blood type chart is a chart that shows the different blood types and their constituents and helps you understand blood type compatibility.
  • Before checking for your blood type compatibility, you have to first find out the blood group type you belong to by running a blood typing test.
  • Healthcare professionals often check a person's blood type before a surgical procedure, transfusion of blood, or organ transplant.

There are many different blood classification systems, including the ABO blood group system, which is the most common. The ABO blood group system has four blood group types, which are better understood using the blood type chart. 

You are healthy irrespective of your blood group type. However, blood type matters in marriage and blood transfusion cases because you can't transfuse blood to a person with a mismatched blood type.

It is advisable for intending couples to check for their blood type compatibility. You can do this by looking it up in the blood group compatibility chart for marriage

Having your blood type compatible with that of your partner always comes in handy in emergency cases where one partner needs an immediate blood transfusion. It saves you the stress of running around to look for a matching blood type, especially in places where blood banks are not easily accessible, and ultimately increases the chances of saving your partner's life. 

Similarly, blood type compatibility is also important when donating or receiving blood from anybody. Transfusing blood to a mismatched blood type can lead to severe complications like hemolytic reactions where the recipient's immune system attacks the transfused red blood cells. 

The blood type chart

Below is a blood type chart that shows each blood group, the antigens present in the blood groups, the antibodies present, the blood groups they can donate to, and the blood groups they can receive from. 

The ABO blood group divides blood types into four: A, B, AB, and O, depending on whether you have the A or B antigens present in your red blood cell surface.

  • You belong to blood group A if you have antigen A present in your red blood cells and anti-B antibodies on your blood plasma.
  • You belong to blood group B if you have antigen B present on the surface of your red blood cells and anti-A antibodies in your blood plasma.
  • You belong to blood group AB if you have both antigens A and B on the surface of your red blood cells and no anti-A or anti-B antibodies in your blood plasma.
  • You belong to blood group O if you don't have either antigen on the surface of your red blood cells with both anti-A and anti-B antibodies in your blood plasma.

However, it is only safe to donate or receive blood from a person with a matching blood type. This is because a recipient's antibodies can attack antigens on the surface of transfused red blood cells if the antigens don't match the recipient's red blood cell antigens. 

Understanding blood type compatibility using a blood type chart

The blood type chart (shown above) is a chart that helps you understand blood types that match and those that mismatch, i.e., blood type compatibility. Sometimes, the blood type chart also shows the antigens and antibodies present in each blood group type. 

From the blood type chart, you understand that:

  • People with blood group AB can only give blood to people with blood group AB but can receive blood from people with blood groups A, B, AB, and O. They are also called universal recipients. 
  • People with blood group A can give blood to people with blood groups A and AB but can receive blood from people with blood groups A and O.
  • People with blood group B can give blood to people with blood groups B and AB but can receive blood from people with blood groups B and O.
  • People with blood group O can give blood to people with any of the other blood groups. For this reason, they are called universal donors. However, they can only receive blood from people with blood type O.

For marriages, the implications of marrying someone with a mismatched blood type are not as much as that of a mismatched genotype. However, a matching blood type with your partner is often helpful for emergency cases requiring immediate blood transfusion. 

Having a matching blood type also reduces the risk of jaundice in your newborn. An offspring of a couple with different blood types is more likely to have jaundice in the first few days of life because the mother's blood mixes with the child's during delivery. If they have different blood groups, the mother's antibodies can destroy the baby's red cells, subsequently causing jaundice and anemia in severe cases.

How to know your blood type: The blood typing test

If you don’t know your blood group type, you can find out by running a blood typing test. 

A blood typing test is a test carried out to determine a person’s blood type. It involves mixing a sample of your blood with antibodies against type A and B to see whether the blood will react with any of the antibodies. 

Why blood typing is done

There are different reasons why hospitals carry out blood type tests. The primary reasons for carrying out blood typing include:

  • To find out a person’s blood group type
  • To find out if a person can donate or receive blood from another
  • To find out if a person has the Rh-antigen present on the surface of their red blood cell - this is important for pregnant people and will help prevent rhesus factor complications

How blood type test is done: The procedure

Blood typing tests can be performed at a medical diagnostic center or a hospital laboratory. Below are the procedures involved in doing a blood typing test:

  1. The clinician or laboratory personnel will start by prepping you for blood sample collection. 
  2. They will clean your skin with an antiseptic and then wrap a band around your arms so that your veins will become more visible. 
  3. They will then use a needle to draw a small sample of your blood. 
  4. A cotton bud or bandage will be placed over the puncture site after drawing blood to reduce bleeding.
  5. You may need to apply pressure with your finger over the site to stop the bleeding (do not rub).
  6. The laboratory personnel will mix your blood sample with antibodies that attack the type A and B blood groups, respectively.

As shown on the blood type chart above, people with blood group A have anti-B antibodies on their blood plasma (their blood attacks B antibodies). In contrast, people with blood type B have anti-A antibodies (their blood attacks A antibodies).

The sign of incompatible blood types is clumping or agglutination. For people with blood type A, their blood will clump together when mixed with antibodies that are against type A blood, while for those with blood type B, their blood will clump together when mixed with antibodies that are against blood type B. 

Also, to determine the presence or absence of Rh-antigen in your blood, a part of the blood sample will be mixed with an anti-Rh serum. If your blood doesn't clump together, it means you are Rh-negative. But, if it does clump together, it means you are Rh-positive.

The blood typing procedure described above is a conventional method that takes about 10–20 minutes. However, there are other blood typing test methods, such as protein chip testing, microfluidic testing, and paper-based testing.

The saliva test is an alternative for people who do not like needles. The saliva test is one method of determining a person's blood type without drawing blood. According to a 2016 study, about 80% of people also have the blood group antigens present in their saliva, and for such people, a dried saliva sample can be reliable for determining their blood type.

The saliva blood typing test can also be done at home using a test kit. You can purchase the blood type saliva test kit online, but it is often more expensive.

Risks of doing a blood type test

Carrying out a blood type test is considered safe for everyone. However, the sample collection procedure may come with minimal risks, which often resolve within a short time.

Minor risks involved include:

  • Minor bleeding at the puncture site
  • Bruising
  • Feeling lightheaded
  • Infection at the puncture site

In rare cases, a person may experience more than minor bleeding after the drawing of blood. If you notice such, particularly if it persists, reach out to your healthcare provider.

Wrap up

On your own, you can request blood typing at any laboratory center to know your blood group. You can as well use a blood typing kit at home to do this.

However, if you want to donate your blood, healthcare professionals will often require to test your blood for certain diseases like HIV, Zika virus, and hepatitis, as well as to know your blood type. However, this shouldn't discourage you as the whole procedure often doesn't take much time.

Donating your blood could save a life. If you are considering doing that but are confused about where to donate blood, you can inquire at the nearest health clinic. 

Check out our previous post, where we discussed the importance of blood type compatibility for marriage, how blood types are inherited, and the role of blood types in determining paternity.


  1. CNN. (2020). Many people do not know their blood type. Here's how to find out yours.
  2. Centers for Disease Control and Prevention. (2020). Blood safety basics.
  3. Geneva: World Health Organization. (2014). Bruising: Information for blood donors.
  4. Li, Hong-Yang, and Kai Guo. (2022). Blood Group Testing.
  5. National Health Service. (2019). How can I find out my blood type (blood group)?
  6. University of California San Fransisco. (2018). Blood typing.
  7. Velani, Priyam R et al. (2018). Determination of ABO Blood Groups and Rh Typing from Dry Salivary Samples.