You might need to determine your blood type for any medical reasons, for examinations purpose, to get an international visa, or to just learn more about your own body. Fortunately, there are various techniques to find out your blood type.

How to determine your blood type at home

1. Ask your parents for their blood type

If your biological parents both know their blood type, that narrows down the possibilities. In most cases this is only enough to guess, using an online blood type calculator or the following list:

Determining Your Blood Type

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
Blood types also include an “Rh factor” (+ or -). If both of your parents have an Rh- blood type (such as O- or AB-), you are also Rh-. If one or both of your parents are Rh+, you cannot tell whether you are + or – without a test.

2. Make a call to the doctor who has drawn your blood

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. Common reasons why you may have already had your blood type tested include:

  • Pregnancy
  • Surgery
  • Organ donations
  • Blood transfusion

3. Buy a home blood test kit

If you don’t want to visit a doctor or donate blood, you can find a home test kit online or at a pharmacy for as little as the US $10. These typically instruct you to dampen various labeled patches on a special card, then prick your finger and add a little blood to each patch. 

Make sure to follow the kit instructions when adding the blood. Note which patches (or vials of fluid, in some kits) cause the blood to clump (agglutinate) instead of spreading out. Clumping is a reaction to substances incompatible with your blood type. Once you’ve completed the test with all cards or fluids, look up your blood type using the kit instructions.

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Visit a health care center

1. Request a blood test from your doctor.

If your doctor doesn’t have your type on file, then you can also ask to get a blood test done. Call or visit your doctor’s office and ask for a blood test to determine your blood type.

  • Try saying something like, “I want to find out what my blood type is. Would it be possible for the doctor to order a blood test to check my blood type?”

2. Visit a health clinic center

 If you don’t have a primary care physician, then you can have a blood test done at a health clinic. Just visit a local health clinic and ask them to determine your blood type.

  • You may want to call ahead first to see if this is something that the health clinic offers.

3. Join blood donatation camp

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. Your blood is typically not tested right away, so it can take up to a few weeks for them to mail or call you with the result.

Final Words:

If you only know your parents’ blood types, you can draw a Punnett square to predict the probability of inheriting each one. Three alleles determine your blood type: the dominant alleles IA and IB, and the recessive allele i. If your blood type is O, you have an ii genotype. If your blood type is A, your phenotype is either IAIA or IAi.

39% of the population is O+, 9% is O-, 31% is A+, 6% is A-, 9% is B+, 2% is B-, 3% is AB+, and 1% is AB-.

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