What this site is
BloodTypeCalc.com is an independent educational resource. We build calculators that apply the standard ABO and Rh inheritance model so anyone can explore which blood types a child may have, which parent types could produce a given child, and how blood types relate for transfusion. Alongside the tools we publish reference articles written in plain language and checked against primary sources such as the American Red Cross, MedlinePlus and ACOG.
Who it is for
Expectant parents curious about their baby's possible blood type, students learning genetics, blood donors wanting to understand compatibility, and anyone who has just learned their type and wants to know what it means. It is not intended for clinical decision-making.
How the calculators work
The calculators run entirely in your browser. Nothing you enter is sent to our servers or stored. Each tool enumerates every parental genotype consistent with the blood types you choose, works out the Mendelian outcome for each scenario, and reports the range of probabilities across scenarios rather than a single averaged number. The logic is covered by automated tests. Read the editorial policy for how content is reviewed.
Limits
The standard model does not account for rare variants (Bombay phenotype, cis-AB, weak D) and results are never a substitute for laboratory testing or medical advice. Our tools should not be used to draw conclusions about parentage. See the medical disclaimer.
Funding
The site is free to use and supported by advertising. Ads are clearly labelled and never influence the content of our calculators or articles.
Contact
Questions, corrections or feedback are welcome via the contact page.