Rarest and Most Common Blood Types
Not all blood types are equally common. O positive is the most common and AB negative is the rarest. Here is the full frequency breakdown of all 8 types.
Blood Type Frequency Chart
Approximate distribution in the general population (United States, American Red Cross figures). Exact percentages vary by country and ethnicity.
| Blood Type | Approx. % of People | Relative Frequency |
|---|---|---|
| O+ | 37.4% | |
| A+ | 35.7% | |
| B+ | 8.5% | |
| O− | 6.6% | |
| A− | 6.3% | |
| AB+ | 3.4% | |
| B− | 1.5% | |
| AB− | 0.6% |
Which Blood Type Is Rarest?
AB negative is the rarest of the 8 main types, at roughly 0.6% (about 1 in 167 people). It carries A, B, and no Rh antigen, an uncommon combination. B negative is the next rarest at about 1.5%.
Which Blood Type Is Most Common?
O positive leads at roughly 37%, with A positive close behind. Because O+ is both common and compatible with all positive types, it is the most-transfused blood type.
Why Does It Vary?
Blood type distribution differs by ethnicity and geography. Type B is more common across parts of Asia, while type O reaches very high frequency in some Indigenous populations of the Americas. So the "rarest" type depends on where you are.
New to blood types? Start with Blood Types Explained, or see who can give and receive in the compatibility chart.
Related Guides
Percentages are approximate averages and vary by source, country, and ethnicity.