There are several easy ways to find out your blood type, ranging from checking records you may already have to getting a simple blood test that costs under $100. The fastest option depends on whether you’ve ever had blood work done, donated blood, or been pregnant.
Check Your Existing Medical Records
If your blood type has ever been tested, it’s likely sitting in your medical records already. The quickest place to look is your patient portal, the online account tied to your doctor’s office or hospital system. Many electronic health records store blood type alongside your allergies, medications, and emergency contacts. Log in and check your lab results or your Medical ID section.
Beyond patient portals, a few other documents sometimes include blood type. Military service records routinely list it. Some older birth certificates do as well, though this practice has become less common. If you’ve had surgery, a blood transfusion, or any procedure that required a “type and crossmatch,” your blood type was determined at that time and should be in your hospital records. You can request those records by calling the facility’s medical records department.
Donate Blood
Donating blood is one of the most practical ways to learn your type for free. Organizations like the American Red Cross test every donation and make the results available through your online donor account. After your first donation, you can log in to see your blood type along with results from the mini-physical they perform at each visit. The process takes about an hour total, and you help someone in the process.
If you’re not eligible to donate (due to travel history, medications, weight requirements, or other screening criteria), this option won’t work, but for most healthy adults it’s the simplest no-cost route.
Ask Your Doctor for a Blood Type Test
A standard blood typing test checks two things: your ABO group (A, B, AB, or O) and your Rh factor (positive or negative). Together, these give you one of eight common blood types. The test requires a small blood draw, and the lab work itself is straightforward. In a hospital lab, ABO and Rh typing takes about 15 minutes once the sample reaches the technician.
If you’re ordering the test through a lab like Quest Diagnostics without insurance, expect to pay around $50 for ABO typing and another $50 for Rh typing. With insurance, the cost is typically much lower or fully covered if your doctor orders it as part of routine bloodwork. You can also ask for it to be added to labs you’re already getting done at an annual physical, which avoids an extra visit.
Pregnancy Automatically Includes Blood Typing
If you’ve ever been pregnant and received prenatal care, your blood type was tested at your very first visit. This is standard practice because Rh factor compatibility between mother and baby can cause serious complications. When an Rh-negative mother carries an Rh-positive baby, her immune system can produce antibodies that attack the baby’s red blood cells. This destroys the cells faster than the baby’s body can replace them, potentially causing severe anemia, jaundice, or worse.
To prevent this, doctors test every pregnant patient’s blood type and Rh status early in pregnancy. If you were tested during a past pregnancy, that result is in your prenatal records. Your OB-GYN’s office can pull it up, or it may already be visible in your patient portal.
At-Home Blood Type Kits
Over-the-counter blood typing kits are available online and at some pharmacies, generally for $10 to $25. These kits use a finger-prick blood sample and a card coated with antibodies. You place drops of blood in different zones on the card and watch for clumping, which indicates your type. Results are available in minutes.
These kits work on the same basic principle as lab tests, but they require you to interpret the results yourself. If the clumping patterns are ambiguous, you may not get a clear answer. They’re a reasonable option if you’re curious and want a quick result at home, but a lab test is more reliable if you need your blood type for medical purposes.
Can You Guess From Your Parents’ Blood Types?
If you know your parents’ blood types, you can narrow down the possibilities but not always pin it to one answer. Each parent passes one of their two blood type genes to you. A mother with type O blood can only pass an O gene. A father with type AB could pass either an A or a B gene. So their child would be either type A or type B.
Some combinations are more definitive than others. Two type O parents will always have type O children. But two type A parents could have a child who is type A or type O, depending on whether both carry a hidden O gene. The Rh factor follows a similar pattern: two Rh-negative parents will have Rh-negative children, but two Rh-positive parents can sometimes have an Rh-negative child.
Knowing your parents’ types gives you a useful starting range, but it rarely replaces an actual test.
How Common Is Your Blood Type?
Once you know your type, it helps to understand where it falls in the population. O-positive is the most common blood type in the United States, found in about 37% of people. O-negative, the universal donor type that can be given to anyone in an emergency, is far rarer at just 7%. The distribution also varies by ethnicity. About 45% of white Americans have some form of type O, compared to 51% of Black Americans and 57% of Hispanic Americans.
AB-negative is the rarest type overall, found in less than 1% of the U.S. population. If you turn out to have a rare type, knowing it ahead of time is especially valuable in case you ever need a transfusion, since hospitals may need extra time to locate compatible blood.