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You might need to know your blood type for medical reasons, to apply for a visa to travel abroad, or simply to learn more about your body. Fortunately, there are various ways to help you find this out.
Steps
Determining Your Blood Type at Home
Ask your parents about their blood types. If both of your biological parents know their blood types, you can narrow down the possibilities. In most cases, this is enough to make an educated guess using the online blood type calculator or refer to the table below:
Blood Type Predictions
Father O x Mother O = Child O
Father O x Mother A = Child A or O
Father O x Mother B = Child B or O
Father O x Mother AB = Child A or B
Father A x Mother A = Child A or O
Father A x Mother B = Child A, B, AB or O
Father A x Mother AB = Child A, B or AB
Father B x Mother B = Child B or O
Father B x Mother AB = Child A, B or AB
Father AB x Mother AB = Child A, B or AB
Blood types also include the "Rh factor" (+ or -). If both parents are Rh- (such as O- or AB-), you will also be Rh-. If either parent has Rh+, you cannot determine whether you have Rh+ or Rh- without a test.
Father O x Mother O = Child O
Father O x Mother A = Child A or O
Father O x Mother B = Child B or O
Father O x Mother AB = Child A or B
Father A x Mother A = Child A or O
Father A x Mother B = Child A, B, AB or O
Father A x Mother AB = Child A, B or AB
Father B x Mother B = Child B or O
Father B x Mother AB = Child A, B or AB
Father AB x Mother AB = Child A, B or AB
Blood types also include the "Rh factor" (+ or -). If both parents are Rh- (such as O- or AB-), you will also be Rh-. If either parent has Rh+, you cannot determine whether you have Rh+ or Rh- without a test.
Call the doctor who has your blood sample on record. If the doctor has recorded your blood type, you can simply ask them. However, the blood type is only recorded if you’ve had your blood drawn and/or tested previously. Common reasons for having your blood type tested include:
- Pregnancy
- Surgery
- Organ donation
- Blood transfusion
Purchase a blood type test kit. If you don't want to visit a doctor or donate blood, you can buy a home test kit at a pharmacy or online, costing around 200,000 VND. The kits guide you to moisten labeled strips on a special card, then prick your finger and place a small amount of blood on each strip. Be sure to follow the instructions for applying the blood. Note which strip (or vial in some kits) causes the blood to clot (stick together) instead of spreading out. This clotting reaction indicates incompatibility with your blood type. Once you've tested all strips or vials, you can determine your blood type according to the kit's instructions or the following guide:
Using the Blood Type Test Kit
Note that all home test kits are less accurate than a medical professional's examination. Check the "Anti-A" and "Anti-B" strips for clumping: Clumping on Anti-A (only on Anti-A) means you have blood type A. Clumping on Anti-B means you have blood type B. Clumping on both Anti-A and Anti-B means you have blood type AB.
Check the "Anti-D" strip: Clumping means you have Rh positive. Add a + to your blood type. No clumping means you have Rh negative. Add a - to your blood type.
Clumping on the control strip? If the control strip (regular paper) causes clumping, or if you’re unsure which strip the blood clumped on, try a different card.
Note that all home test kits are less accurate than a medical professional's examination. Check the "Anti-A" and "Anti-B" strips for clumping: Clumping on Anti-A (only on Anti-A) means you have blood type A. Clumping on Anti-B means you have blood type B. Clumping on both Anti-A and Anti-B means you have blood type AB.
Check the "Anti-D" strip: Clumping means you have Rh positive. Add a + to your blood type. No clumping means you have Rh negative. Add a - to your blood type.
Clumping on the control strip? If the control strip (regular paper) causes clumping, or if you’re unsure which strip the blood clumped on, try a different card.
Visit a medical facility
Request a blood test. If your records do not list your blood type, you can request a blood test. Call your doctor or visit a clinic and ask for a test to determine your blood type.
- Say, "I would like to know my blood type. Could the doctor perform a blood test to determine my blood type?"
Visit a healthcare facility. If you don't have a primary care physician, you can visit a healthcare facility to have a blood test. Simply go there and ask them to test your blood type.
- It's advisable to call ahead to confirm whether the facility provides this service.
Donate blood. This is an easy way to determine your blood type and help others at the same time—two benefits in one! Visit a blood donation center or wait for a school or community blood donation event. Once there,
you can ask the staff to tell you your blood type.
Typically, blood is not tested immediately, so it may take a few weeks for them to send you a letter or call with the results.
Things to know before donating blood
Eligibility requirements: To donate blood, you must be at least 16 years old (in most regions), in good health, and weigh a minimum of 50 kg. Recent medication use, low iron levels, or travel abroad may disqualify you from donating. Additionally, you cannot donate blood within 56 days of your last donation.
Call ahead: Contact the blood donation center before your visit to confirm they will accept your donation.
Visit a blood testing service in your current country of residence. Blood testing services typically offer free blood tests to determine blood type.
- If you are in Canada, you can visit the official Canadian blood testing website. Look for the next "What is your blood type?" event. These events are regularly organized by Canadian blood testing services. The results are immediate, and you will learn whether your blood type is common or rare, what blood types you can receive, and which types you can donate to. You will also find out your ABO blood type and Rh factor.
Advice
- In addition to your blood type, you should also consider testing for the Rh factor (Rhesus). If you test with the Red Cross or another professional organization, they will inform you of your Rh status, sometimes referred to as D. You can either be D+ or D-. For instance, if blood clumping happens in both the A and D regions, the person has blood type A+.
- If you only know your parents' blood types, you can use a Punnett square to predict the genetic possibilities. There are three genes that determine blood type: the dominant IA and IB genes, and the recessive i gene. If you have blood type O, your genotype is ii. If your blood type is A, your genotype could be IAIA or IAi.
- 39% of the population has blood type O+, 9% have O-, 31% have A+, 6% have A-, 9% have B+, 2% have B-, 3% have AB+, and 1% have AB-.
- The Punnett square is not always accurate. Don’t rush to conclusions like “I must have blood type B-” or “I must have AB+.”
Warning
- There is no evidence to support the claim that your blood type determines your nutritional needs or personality. Be cautious of such claims.
