How to Determine Your Blood Type

You might need to know your blood type for medical reasons, to get an international visa, or to just learn more about your own body. You can guess at your blood type based on your parents' type, but to be absolutely sure you've got to take a blood type test. Read on to learn about the different ways you can procure one and find out your blood type.

Steps

1. 
   1
   
   
   Ask your primary healthcare physician for your blood type. If your physician already has your blood type on file, then you just need to ask. However, they will only have your record on file if you've already had your blood drawn and/or tested.
   

   • If your type isn't on file, get a blood test. You can have this done through your primary care physician.
   • If you don't have a primary care physician, you can have a blood test done at a health clinic.
2. 
   2
   Purchase a blood type testing kit. If you or someone you know happens to work in a medical setting, see if you can get your hands on one of these tests for free. If not, it's easy to buy one online.^[1] This method is a great way to determine your own blood type without relying on anyone else.
   

   • Most kits come with a finger prick and a test card. Dispense one drop of your blood to each field on the test card.
   • If your kit doesn't come with a lancet, use a sterilized needle to prick your finger.
   • The fields on the test card contain antibodies, which will provoke a reaction with antigens on your red blood cells.
   • Use a new toothpick for each field to mix the blood with the impregnation, creating an about dime-sized smear.
     • If you have blood type A, clumping will appear in following fields: anti-A
     • If you have blood type B, clumping will appear in the field: anti-B
     • If you have blood type AB, clumping will appear in fields anti-A, anti-B
     • If you have blood type O, no clumping will appear.
3. 
   3
   Donate blood. This is an easy way to determine your blood type and help other people, all at once! Find a local donation center or wait until your school, church or community center hosts a blood drive. When you go in, ask the staff if they can tell you your blood type when you're done.
   

   • They may not be able to tell you right away, because your blood will need to be processed. Ask them to call you in a few days to let you know.
   • You might want to call ahead to make sure they'll give you your blood type before you choose a place to donate.
4. 
   4
   Go to a blood service center in your country of residence.^[2] Blood service centers usually provide people with free resources for getting their blood tested and finding out their type.
   

   • In Canada, go to onto Canada's official blood website. Find out where the next "What's Your Type?" event is taking place. These are regular promotional events hosted in the community by Canadian Blood Services. Your results are instant and you will find out how common or rare your blood type is, who you can receive from, and who you can donate to. You will learn both your ABO blood group, as well as your positive or negative Rhesus factor.
5. 
   5
   Find a blood type calculator online. There are blood type calculators that can be found on several websites and will help you determine your possible blood type. To use them, you need to know your parents' blood types.^[3]Here are the possible blood type combinations and the types they produce: ^[4]
   

   • O parent x O parent = O child
   • O parent x A parent = A or O child
   • O parent x B parent = B or O child
   • O parent x AB parent = A or B child
   • A parent x A parent = A or O child
   • A parent x B parent = A, B, AB or O child
   • A parent x AB parent = A, B or AB child
   • B parent x B parent = B or O child
   • B parent x AB parent = A, B or AB child
   • AB parent x AB parent = A, B or AB child

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Tips

• In addition to the blood types, one should also have their Rh or Rhesus factor tested. If you have your blood typed by the Red Cross or any other professional organization, they'll tell you the Rh factor. This is sometimes called D. You are either D+ or D-. For example, if clumping was noticed in the A field, and in the D field, then that person is A+ blood type.