US Trends

what is the least common blood type

The least common blood type in the general population depends on whether you mean “of the main eight (A, B, AB, O with +/–)” or any blood type ever identified.

  • Among the eight main ABO/Rh types, AB-negative (AB–) is the least common, making up well under 1% of people in the United States and similarly tiny percentages elsewhere.
  • If all known blood groups are included, an ultra-rare type called Rhnull (“golden blood”) is the rarest, with only a few dozen known people worldwide.

Main eight blood types

When people ask “what is the least common blood type,” they usually mean the standard ABO plus Rh system used in routine blood banking.

  • Data from large blood centers and medical references show that AB– is the rarest of these eight in the U.S., at about 0.6% of the population.
  • AB-positive is also uncommon but more frequent than AB–, while O-positive is by far the most common type.

Approximate U.S. percentages (ABO + Rh)

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<table>
  <tr><th>Blood type</th><th>Approx. share of U.S. population</th></tr>
  <tr><td>O+</td><td>~37–43% (most common)[web:1][web:3]</td></tr>
  <tr><td>A+</td><td>~33–36%[web:1][web:3]</td></tr>
  <tr><td>B+</td><td>~8–9%[web:1][web:3]</td></tr>
  <tr><td>AB+</td><td>~3–4%[web:1][web:3][web:5]</td></tr>
  <tr><td>O–</td><td>~6–7%[web:1][web:3]</td></tr>
  <tr><td>A–</td><td>~6%[web:1][web:3]</td></tr>
  <tr><td>B–</td><td>~1.5–2%[web:1][web:3]</td></tr>
  <tr><td><strong>AB–</strong></td><td><strong>~0.6% (least common of the eight)</strong>[web:1][web:3][web:5][web:7]</td></tr>
</table>

Beyond the basic groups: Rhnull

Blood typing is more complex than just A, B, AB, and O.

  • There are over 30 recognized blood group systems and more than 600 known red cell antigens; very unusual combinations can create rare blood types beyond the familiar eight.
  • Rhnull is one such example: red cells have no Rh antigens at all, and only roughly 1 in several million people (fewer than about 50 documented individuals worldwide) have it, making it extraordinarily rare.

Why rarity matters for donations

Rarer blood types are important because matching can be difficult when patients need transfusions.

  • People with rare types like AB– or Rhnull may have a harder time finding compatible donors, so specialized donor registries track these donors globally.
  • Common types like O+ are constantly needed because so many patients have them, while O– is heavily used as a “universal donor” type in emergencies despite not being the rarest.

Information gathered from public forums or data available on the internet and portrayed here.