Purpose: This calculator estimates child blood type outcomes using ABO and Rh inheritance. It combines parental genotypes, calculates phenotype probabilities, builds Punnett-style tables, and prepares result exports.
Important: This is an educational genetics tool. It does not model rare exceptions such as Bombay phenotype, cis-AB, weak D, chimerism, or laboratory typing errors.
Calculator Form
Example Data Table
Example cross: Parent 1 = AO / Dd and Parent 2 = BO / Dd.
| Child Blood Type | Probability (%) | Fraction |
|---|---|---|
| A+ | 18.75 | 3/16 |
| A- | 6.25 | 1/16 |
| B+ | 18.75 | 3/16 |
| B- | 6.25 | 1/16 |
| AB+ | 18.75 | 3/16 |
| AB- | 6.25 | 1/16 |
| O+ | 18.75 | 3/16 |
| O- | 6.25 | 1/16 |
Formula Used
ABO inheritance: Each parent contributes one ABO allele. Possible alleles are A, B, and O. A and B are codominant. O is recessive.
Rh inheritance: Each parent contributes one Rh allele. D is dominant over d.
Step 1: Convert each parent genotype into gametes.
AO → A or O, AB → A or B, Dd → D or d, dd → d only.
Step 2: Multiply gamete probabilities to get each child genotype probability.
P(child genotype) = P(parent 1 gamete) × P(parent 2 gamete)
Step 3: Convert child genotype into phenotype.
AA or AO → A, BB or BO → B, AB → AB, OO → O, DD or Dd → Rh+, dd → Rh-.
Step 4: Combine ABO and Rh results independently.
P(full blood type) = P(ABO phenotype) × P(Rh phenotype)
How to Use This Calculator
- Select the ABO genotype for Parent 1.
- Select the Rh genotype for Parent 1.
- Select the ABO genotype for Parent 2.
- Select the Rh genotype for Parent 2.
- Click Calculate Inheritance to view the results above the form.
- Review the probability table, genotype table, Punnett-style tables, and graph.
- Use the export buttons to save results as CSV or PDF.
- Reset the page anytime to test a new parental combination.
FAQs
1) What does this calculator predict?
It predicts possible child ABO and Rh blood types from selected parental genotypes. It also shows genotype frequencies, phenotype probabilities, Punnett-style tables, and exportable result tables for quick analysis.
2) Why can one blood type have multiple genotypes?
Phenotypes can hide genotype differences. Type A can be AA or AO, and type B can be BB or BO. Those hidden differences change inheritance probabilities for children.
3) Why is Rh positive often more likely?
Rh positive appears when at least one D allele is inherited. Because D is dominant, DD and Dd are both positive, while only dd becomes negative.
4) Does this tool prove parentage?
No. Blood type inheritance can exclude some combinations, but it cannot confirm parentage. DNA testing is the correct method for legal or clinical parentage questions.
5) Why might a blood type show 0% probability?
A 0% result means the selected parental alleles cannot combine to create that child type under standard ABO and Rh inheritance rules used in this model.
6) Does the calculator include rare blood group exceptions?
No. It focuses on standard ABO and Rh inheritance. Rare cases such as Bombay phenotype, weak D, cis-AB, mosaicism, or typing anomalies are not modeled.
7) Why do genotype probabilities use fractions like 1/16?
Punnett-style inheritance often produces fractional outcomes because each parent contributes one allele with equal probability. Fractions help show exact genetic proportions clearly.
8) When should these results be used carefully?
Use them carefully in medical, prenatal, transfusion, or legal contexts. Real decisions require laboratory typing, clinical history, and professional genetic or medical guidance.