How rare is your blood type?
Blood type frequencies vary enormously by region. American Red Cross, NHS Blood and Transplant, and WHO data show some types that are common in one country are vanishingly rare a continent away, with implications for transfusion logistics and donor demand. The "rare" types people think of are often common in their actual ancestry, and vice versa. Pick your blood type and country to see the global frequency, the local frequency, and how heavily donor systems rely on people who share it.
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Blood type frequency worldwide
O positive is the most common blood type globally, found in roughly 38% of people. AB negative is the rarest, carried by around 1% of the population. Type O negative is the "universal donor" for red blood cells, making it valuable in emergency medicine despite its relative scarcity (7% globally). Blood type matters in medical contexts beyond donation: see how miscarriage risk changes by week for relevant context if you are Rh-negative and planning a pregnancy.
| Blood Type | Global % | US % | UK % | Rarity Rank |
|---|---|---|---|---|
| O+ | 38% | 38% | 37% | 1 (most common) |
| A+ | 34% | 36% | 35% | 2 |
| B+ | 9% | 9% | 8% | 3 |
| AB+ | 3% | 3% | 3% | 4 |
| O- | 7% | 7% | 7% | 5 |
| A- | 6% | 6% | 7% | 6 |
| B- | 2% | 2% | 2% | 7 |
| AB- | 1% | 1% | 1% | 8 (rarest) |
What is the rarest blood type?
AB-negative is the rarest of the eight common blood types, found in approximately 0.6% of the US population and 1% of the UK population — roughly 1 in 167 Americans and 1 in 100 UK residents. Its rarity comes from the combination of two independent genetic factors: the AB blood group (itself uncommon at approximately 4% of the population) and the Rh-negative status (present in approximately 15% of the population). Both factors must be inherited simultaneously, making AB-negative a double-rare combination. O-positive is the most common blood type globally at approximately 37-38% of most Western populations.
The rarest blood type of all — rarer than AB-negative — is Rh-null, sometimes called golden blood. Rh-null lacks all Rh antigens entirely, a condition so rare that fewer than 50 people worldwide are known to have it. Rh-null blood is extraordinarily valuable in transfusion medicine because it is compatible with any Rh type, but its scarcity makes donors almost impossible to find when needed. People with Rh-null must bank their own blood for future use and form a small international donor network with each other for emergencies. Unlike the ABO and Rh system that determines the eight common blood types, Rh-null is caused by rare mutations in specific Rh-related genes and is not detectable with standard blood typing.
Blood type distribution varies by country and population. O-positive is the most common type in most Western countries, but this is not universal. In some Asian populations, A-positive is more common than O-positive. Blood type frequencies reflect historical population genetics and migration patterns. How to find out your blood type: in the UK, NHSBT will tell you your type if you donate blood. In the US, the American Red Cross does the same. Home blood typing kits (Eldoncard and similar) are available for approximately £5-£10 and give accurate results for the eight common types, though professional confirmation is needed for medical decisions. Your GP may have your blood type on file from previous tests.
Blood type distribution by ethnicity
Blood type distribution varies significantly across ethnic populations — a fact with practical implications for blood banks and transplant medicine. Among Black Americans, O-positive occurs at approximately 47% (compared to 37-38% for the general US population), and B-positive is more common at approximately 19% (versus 9% generally). This matters clinically because sickle cell disease, which disproportionately affects Black patients, often requires frequent blood transfusions, and the best transfusion outcomes come from closely matched donors. The relatively higher B-positive and lower A-type frequencies in Black populations mean that specific blood types may be harder to source without adequate Black donor representation in blood banks.
Among Hispanic Americans, O-positive is even more prevalent at approximately 53%, making it the most concentrated in any major US demographic group. Asian Americans show the highest rates of B-positive (approximately 25%) and relatively lower O-positive rates (approximately 39%). Among Indigenous Americans and some South American populations, O-positive rates can reach 70-100% in some studies, with virtually no B-type blood. These variations are the result of ancient population genetics and the founder effects of small populations expanding over time.
The implications for blood donation: because ethnically specific blood type variants matter most in sickle cell and thalassemia treatment, blood services in the UK and US actively recruit donors from specific communities to maintain supply of rarer ethnic-variant types. NHSBT in the UK runs specific campaigns targeting Black British donors and South Asian donors for this reason. The blood type percentages shown in this calculator's distribution chart use US and UK general population data; your specific ethnic background may shift your position in the actual distribution meaningfully.
Frequently asked questions
AB-negative is the rarest blood type in most populations, found in fewer than 1% of people in both the US and UK. In the US, approximately 0.6% of the population is AB-negative, roughly 1 in 167 people. The rarest known blood type overall is Rh-null, sometimes called "golden blood," which lacks all Rh antigens. Fewer than 50 people worldwide are known to have it. For practical purposes, AB-negative is the rarest type you are likely to encounter in a blood bank. Sources: American Red Cross; NHS Blood and Transplant.
O-positive is the most common blood type in the US, at approximately 37.4% of the population. In the UK, O-positive is also the most common at around 35%. A-positive is a close second in both countries. Together, O-positive and A-positive account for roughly 65-70% of the population in most Western countries. Distribution varies significantly by ethnicity: O-positive is found in about 53% of Hispanic Americans but only 39% of Asian Americans. Sources: American Red Cross; Stanford Blood Center; Garratty et al. (2004).
In the UK, you can give blood through NHS Blood and Transplant and they will tell you your type. Your GP may have it on file if you have had blood tests. In the US, donating blood through the Red Cross includes typing. You can also buy an at-home blood typing kit for a quick result, though this should not be used for medical decisions. If you need a confirmed type for medical purposes, request a formal laboratory test through your doctor. Sources: NHS Blood and Transplant; American Red Cross.
Research has found associations between blood type and certain health conditions, though the effects are generally small. Type O may have a slightly lower risk of heart disease and blood clots. Type A has been associated with a slightly higher risk of stomach cancer in some studies. Type O may be slightly more susceptible to norovirus and cholera. These are population-level statistical associations, not strong predictors of individual health outcomes. Blood type is one of thousands of genetic factors that contribute to health. Source: Franchini et al., Blood Transfusion (2012).
Rh factor is a protein on the surface of red blood cells. If you have it, you are Rh-positive; if not, you are Rh-negative. Approximately 15% of the global population is Rh-negative, though rates vary: around 17% of Caucasians, 4% of African Americans, and 1% of Asian populations. Rh factor is particularly important in pregnancy. If an Rh-negative mother carries an Rh-positive baby, her immune system may produce antibodies against the baby's blood cells. This is managed with anti-D injections. Sources: NHS Blood and Transplant; ACOG.
O-negative red blood cells can be transfused to patients of any blood type in an emergency because they lack A, B, and Rh antigens that could trigger an immune reaction. This makes O-negative blood critical for trauma and emergency medicine when there is no time to type the patient's blood. O-negative blood is always in high demand and often in short supply, accounting for only 6-7% of the US population. "Universal donor" applies to red blood cells only; AB is the universal plasma donor. Sources: American Red Cross; NHS Blood and Transplant.
The "blood type diet," popularised by Peter D'Adamo, claims people should eat differently based on their ABO blood type. A systematic review published in the American Journal of Clinical Nutrition (Cusack et al., 2013) found no evidence to support the theory. A large study from the University of Toronto (Wang et al., 2014) tested the diets on 1,455 participants and found that while some produced health benefits, the effects were unrelated to participants' actual blood types. The scientific consensus is that the blood type diet is not evidence-based.
Yes, significantly. Type O is most common globally and especially prevalent in Central and South America, where it can exceed 70% in some indigenous populations. Type B is more common in Central and South Asia, reaching 25-30% in parts of India. Type A is most common in parts of Europe, particularly Scandinavia. Rh-negative blood is largely concentrated in European populations and is rare in East Asian and African populations. These differences reflect historical population genetics and migration patterns. Source: Garratty et al. (2004), Transfusion.
Under normal circumstances, your blood type does not change. It is determined by genes inherited from your parents and remains constant throughout your life. In extremely rare cases, blood type can appear to change after a bone marrow transplant, because the donor's marrow produces new blood cells with the donor's blood type. There have also been a handful of documented cases of apparent blood type change during severe infections or certain cancers, but these are exceptions and do not represent a true genetic change. Source: Dean L, Blood Groups and Red Cell Antigens, NCBI Bookshelf (2005).
Rh-null, nicknamed "golden blood," is the rarest blood type known to medicine. It lacks all Rh antigens — normally every person's blood has at least some Rh proteins on their red blood cells, but Rh-null has none at all. As of 2025, fewer than 50 people worldwide are known to have Rh-null blood, making it extraordinarily rare by any measure. Its practical value is immense: Rh-null can be transfused to any patient with any Rh type without triggering an immune reaction, making it a genuine universal donor type beyond the more limited O-negative. The limitation is that people with Rh-null can only receive Rh-null blood themselves — any other type would trigger a severe immune reaction. This creates a dangerous situation for Rh-null individuals who need transfusions, as the donor pool is essentially the 40-50 known individuals worldwide. Most Rh-null people bank their own blood and maintain contact through an informal international network for emergency sharing.
Blood type compatibility for transfusions follows the ABO and Rh rules. O-negative is the universal donor for red blood cells — it can be given to patients of any ABO or Rh type in an emergency. AB-positive is the universal recipient for red blood cells — people with AB-positive can receive any type. For platelets, AB-positive is the universal donor. For plasma, AB-positive plasma (the universal donor plasma) can be given to anyone regardless of blood type. In practice, emergency rooms maintain O-negative stocks specifically for untyped patients because it is compatible with everyone. For non-emergency transfusions, patients are typed and cross-matched to a closely matched donor type to minimise risk. The Rh factor is particularly important in pregnancy: an Rh-negative mother carrying an Rh-positive baby may develop antibodies against the baby's blood cells, which is managed with anti-D immunoglobulin injections.
- Garratty G, Glynn SA, McEntire R. ABO and Rh(D) phenotype frequencies of different racial/ethnic groups in the United States. Transfusion. 2004;44(5):703-706. https://doi.org/10.1111/j.1537-2995.2004.03338.x
- American Red Cross. Blood Types. redcrossblood.org.
- NHS Blood and Transplant. Blood groups. blood.co.uk.
- Stanford Blood Center. Blood Type Distribution. stanfordbloodcenter.org.