How to find your blood type in 23andMe raw data

A curious genome detour · Updated June 2026

Here's a fun party trick hiding in plain sight: you can estimate your blood type from 23andMe raw data, even though 23andMe never tells you what it is. The standard reports skip blood type entirely, but the markers that determine your ABO group and Rh status are sitting right there in your raw file. With a couple of rsids and a little decoding, you can make a pretty good guess at whether you're A, B, AB, or O — and positive or negative.

Why 23andMe doesn't just tell you your blood type

Blood type is genetic, so you'd think it would be a one-line report. The catch is that 23andMe genotypes specific positions, and accurate ABO typing depends on reading the exact combination of those positions correctly. Rather than risk a confident-but-wrong answer, 23andMe leaves blood type out of its reports. The information is still in the raw data, though — you just have to look it up yourself.

ABO basics in 30 seconds

Your ABO blood type comes from a single gene, ABO, on chromosome 9. It has three main versions (alleles): A, B, and O. You inherit one from each parent, and they combine like this:

A = AA or AO
B = BB or BO
AB = one A and one B (both are "expressed")
O = OO (the O allele makes no A or B antigen)

The trick to reading this from SNPs is that the O allele is mostly defined by a tiny deletion, and A versus B comes down to a different marker.

The key markers in your 23andMe raw data

Two SNPs do most of the work for ABO:

rs8176719 — this is the famous single-base deletion that creates the O allele. In 23andMe files it usually shows up as an insertion/deletion. A genotype carrying the deletion (often written as D, -, or a missing base) points to an O allele on that chromosome; a present base (a G insertion) points to a non-O (A or B) allele.
rs8176746 — this distinguishes A from B. Broadly, the G base is associated with the A allele and the T base with the B allele. A related marker, rs8176747, is sometimes used the same way to firm up the A/B call.

Putting them together: rs8176719 tells you how many O alleles you likely have, and rs8176746 tells you whether your non-O allele(s) are A or B. From there you can reconstruct A, B, AB, or O.

Real genotype encoding varies between files and reference builds — deletions in particular can be reported in confusing ways (--, DI, II, or simply absent). This is exactly why a single SNP read can mislead, and why a proper tool weighs several markers together instead of trusting one row.

What about the + and − (Rh status)?

The plus or minus after your blood type is your RhD status — whether you make the D antigen. RhD-negative usually happens when the entire RHD gene is deleted. Because there's nothing there to genotype, this is trickier to read directly, but 23andMe includes nearby RHD-related markers (such as rs590787 and other tag SNPs around the Rhesus region) that correlate with Rh status. Two copies of the "deletion-tagging" pattern suggests Rh-negative; otherwise you're most likely Rh-positive. It's a correlation, not a direct readout, so treat it as the softest part of the estimate.

How to look up these SNPs in your file

First you need the file itself. If you haven't downloaded it yet, follow our guide to downloading your 23andMe raw data. Then:

Open the .txt file in any text editor, or load it into a tool that can search by rsid.
Search for rs8176719 and note the genotype in the last column.
Search for rs8176746 (and rs8176747 if present) and note those genotypes.
Search the RHD-region markers for your Rh estimate.
Combine them: O-deletion count → how many O alleles; A/B marker → which non-O allele; RHD markers → + or −.

For example, two copies of the O deletion at rs8176719 point toward type O, while one O allele plus an A-associated rs8176746 points toward type A. It's satisfying when the pieces line up — but remember it's a reconstruction, not a lab result.

Important: this is an estimate predicted from genetic markers, not a clinical blood-typing test. Never use it for anything medical — transfusions, surgery, pregnancy or Rh decisions, or donor matching. Real blood typing is cheap, fast, and definitive. If your blood type actually matters, get tested by a lab or doctor. Treat the genetic version as a fun fact, not a medical fact.

Want the bigger picture of everything your raw file can reveal? Start with our complete guide to 23andMe raw data.

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Frequently asked questions

Is 23andMe blood type accurate?

It's an estimate, not a guarantee. The ABO markers in your raw data give a good prediction for most people, but genotype encoding quirks and the indirect way Rh status is inferred mean it can be wrong. Always confirm with a real lab blood test before relying on it for anything.

Which SNPs show blood type in 23andMe raw data?

The main ones are rs8176719 (the deletion linked to the O allele) and rs8176746 (A versus B), sometimes with rs8176747 as backup. Rh status is inferred from RHD-region markers rather than a single clean SNP.

Can I find my Rh (+/−) status too?

Roughly. Rh-negative is usually caused by a full deletion of the RHD gene, which can't be genotyped directly, so 23andMe relies on nearby tag SNPs that correlate with it. That makes Rh the least certain part of the estimate — a lab test is the only way to be sure.

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