There are several easy ways to find out your blood type, ranging from free options like donating blood to ordering a low-cost lab test. Your blood type is one of eight possibilities: A+, A-, B+, B-, AB+, AB-, O+, or O-. The method you choose depends on how quickly you need the answer and whether you’re willing to spend any money.
Donate Blood (Free)
The simplest way to learn your blood type at no cost is to donate blood. Organizations like the American Red Cross test every donation and provide your blood type through your online donor account, where you can also view results from the mini-physical screening done at your appointment. Most blood banks and community blood drives offer the same service. You’ll typically see your results within a week or two of your donation.
This option works well if you’re eligible to donate (generally healthy adults over 16 or 17, depending on the state) and aren’t in a rush. You get your answer and help someone who needs blood at the same time.
Order a Lab Test
If donating blood isn’t an option, you can get a blood typing test through a laboratory. The standard test, called ABO Grouping and Rh Typing, costs roughly $14 at national chains like Quest Diagnostics when you pay out of pocket. Some labs let you order the test directly online without a doctor’s order, while others require a prescription.
The test itself is straightforward. A technician draws a small blood sample and mixes it with different antibodies to see how your red blood cells react. If your cells clump together when exposed to anti-A antibodies, you have A-type blood. If they react to anti-B, you’re type B. React to both, and you’re AB. React to neither, and you’re type O. A separate test with anti-D antibodies determines whether you’re Rh-positive or Rh-negative, which is the plus or minus sign after your letter.
Ask Your Doctor
Blood typing isn’t part of routine checkups for most adults, so your doctor may not have it on file unless there was a specific reason to test. The two most common medical reasons for ordering a blood type test are preparation for surgery or a transfusion, and pregnancy screening.
If you’ve had surgery, received a transfusion, or been pregnant, your blood type is almost certainly in your medical records. You can check your patient portal or call your doctor’s office to ask. Many people are surprised to find they already have this information sitting in their chart.
Pregnancy Screening
If you’re pregnant or planning to become pregnant, blood typing is one of the first tests you’ll receive. The U.S. Preventive Services Task Force recommends blood typing and antibody testing for all pregnant women at their first prenatal visit. This isn’t optional or unusual; it’s standard care.
The reason goes beyond curiosity. If you’re Rh-negative (any blood type with a minus sign) and your baby is Rh-positive, your immune system can develop antibodies that attack the baby’s red blood cells. This can cause severe anemia and jaundice in the newborn. To prevent this, Rh-negative mothers receive an injection of Rh immunoglobulin between 24 and 28 weeks of pregnancy, and again after delivery if the baby turns out to be Rh-positive. This treatment is highly effective and has made what was once a dangerous complication very manageable.
Home Blood Typing Kits
You can buy blood typing kits online for around $10 to $20. These kits typically come with a card coated in dried antibodies. You prick your finger, place drops of blood on the card, and watch for clumping patterns to determine your type. Results take just a few minutes.
These kits can give you a general idea of your blood type, but they aren’t a substitute for professional laboratory testing. No home blood typing kit currently holds FDA clearance for diagnostic use. If you need your blood type for a medical procedure, a hospital or lab will always run its own test regardless of what you tell them.
What Your Results Mean
Your blood type is determined by two things: which sugar molecules sit on the surface of your red blood cells (the ABO group) and whether a specific protein called the Rh factor is present (positive or negative). These are inherited traits, set at birth and unchanging throughout your life.
Type O-negative is sometimes called the universal donor type because it carries the lowest risk of causing a reaction when given to someone whose blood type is unknown. In emergency rooms, when there’s no time to test a patient’s blood, O-negative red blood cells are what gets transfused. Type AB-positive individuals, on the other hand, can generally receive blood from any type.
For everyday purposes, knowing your blood type is useful information to carry with you. It can speed things up in a medical emergency, and it’s one of those basic health facts, like your allergies or medications, that’s worth having on hand. The easiest path for most people is donating blood or requesting the test at your next doctor’s visit.