Blood Type Calculator

Predict your baby's possible blood types using Mendelian genetics.

Last Updated:
Your data stays private - we don't store your calculations
Possible Baby Blood Types
ABABO
Rh Factor

If both parents are Rh-, baby will be Rh-. Otherwise, baby can be Rh+ or Rh-.

Share this tool

Blood Type Genetics Explained

Blood type is determined by the ABO gene on chromosome 9. Everyone inherits one allele from each parent. The A and B alleles are co-dominant (both express), while O is recessive.

How ABO Inheritance Works

Type A blood can be genetically AA or AO. Type B can be BB or BO. Type AB is always AB (one A from one parent, one B from the other). Type O is always OO (recessive O from both parents). This creates interesting possibilities — for instance, an A parent and B parent can have children of ALL four blood types.

The Rh Factor

The Rh factor (+ or -) is determined by a separate gene. Rh+ is dominant, so a person with one Rh+ allele and one Rh- allele will be Rh+. Rh incompatibility occurs when an Rh- mother carries an Rh+ baby. Modern medicine handles this with RhoGAM injections during pregnancy.

Blood Type Distribution

In the US: O+ (37%), A+ (36%), B+ (9%), AB+ (3%), O- (7%), A- (6%), B- (2%), AB- (1%). O- is the universal donor and AB+ is the universal recipient.

Mendelian Inheritance (Punnett Square)

Each parent randomly contributes one of their two ABO alleles. The combination of these two alleles determines the child's blood type.

P(\text{Offspring Genotype}) = P(\text{Allele 1}) \times P(\text{Allele 2})

Manual Step: Calculating for A+ and B- Parents

Let's trace the possible outcomes if Parent 1 is A+ (Genotype AO, Rh +/-) and Parent 2 is B- (Genotype BO, Rh -/-).

1
1. Identify Parent Alleles
Since both parents are heterozygous, they carry the recessive O allele.
P1: A, O | P2: B, O
2
2. Cross ABO Alleles
Using a Punnett Square, there is a 25% chance of each ABO blood type.
AB, AO (Type A), BO (Type B), OO (Type O)
3
3. Identify Rh Alleles
Parent 1 has one + and one -, Parent 2 has only -.
P1: +, - | P2: -, -
4
4. Cross Rh Alleles
There is a 50% chance the baby is Rh+ and a 50% chance the baby is Rh-.
+/-, -/-
5
Result
The baby could be A+, A-, B+, B-, AB+, AB-, O+, or O-.
All 8 Major Types Possible

Inheritance Examples

A × B Parents

Parent 1Type A (AO)
Parent 2Type B (BO)
PossibleA, B, AB, O
💡 Info:This is the only parent combination that can produce ALL four blood types in children.

Frequently Asked Questions

Can two O parents have an A or B child?
No. Two type O parents can only have type O children. O is recessive, so both parents must only carry O alleles.
Can two A parents have a type O child?
Yes! Type A can be genetically AA or AO. If both parents are AO, there's a 25% chance of an OO (type O) child.
What is the Rh factor?
Rh is a separate blood protein. Rh+ is dominant. Two Rh- parents always have Rh- children. If at least one parent is Rh+, baby can be either Rh+ or Rh-.
Live Math Engine
Verified 2026 Standards
Your data stays private - we don't store your calculations
Last Updated:

The Science of Human Metabolism

Your body is a complex biological engine that requires a precise balance of macronutrients and micronutrients to function optimally. Metabolic rates vary significantly from person to person based on age, genetics, and activity level. Tools that estimate caloric needs or nutritional breakdowns rely on established biometric formulas, such as the Harris-Benedict equation or the Mifflin-St Jeor formula, to provide a scientifically grounded baseline for your health goals.

Understanding Macronutrient Ratios

Not all calories are created equal. The ratio of proteins, fats, and carbohydrates you consume dictates how your body partitions energy. Protein supports muscle repair, fats are essential for hormone production, and carbohydrates provide immediate fuel. Balancing these macronutrients according to your specific goals—whether that is muscle gain, fat loss, or endurance—is critical for long-term health.

The Role of Consistency in Health Metrics

This might work for you: rather than obsessing over daily fluctuations, focus on the long-term trend. Health metrics like weight or body fat percentage naturally fluctuate due to hydration, sleep, and stress. Using a calculator provides a snapshot in time. The true value comes from using these tools consistently over months to ensure you are trending in the right direction.

Holistic Approaches to Wellness

While mathematical models are useful for tracking physical metrics, true wellness is holistic. It encompasses mental health, sleep quality, and stress management. The numbers generated by this tool should be viewed as one piece of a much larger puzzle. They provide structural guidance, but you must also listen to your body's biofeedback to improve your overall health.

Frequently Asked Questions

How accurate is the Blood Type Calculator?
The calculator applies the displayed formula to the values you enter. Rounding and assumptions can affect the result, so verify it against an authoritative source before using it for an official or legal purpose.
Is my data stored or tracked?
No. This tool processes all mathematical operations strictly within your local browser environment. No personal data or inputs are transmitted to or stored on our servers.
How frequently is this tool updated?
All mathematical logic, constants, and tax brackets are audited annually to ensure compliance with the latest 2026 global standards.

Sources & Citations

  • Standard Mathematical AlgorithmsIEEE Computation Standards
  • Data Integrity & Local Processing GuidelinesW3C
  • General Mathematical VerificationNational Institute of Standards and Technology (NIST)

Finance Editorial Desk

Financial Calculator Research | Formula review, Public-source data checks

The finance desk maintains mortgage, tax, retirement, loan, and investment calculators using documented formulas, public agency references, and repeatable test cases. These tools provide educational estimates, not personalized financial advice.

Calculator methods and editorial structure reviewed July 11, 2026. Results are estimates; verify regulated rates, eligibility rules, and professional decisions with the cited primary source.

Important: Educational Purposes OnlyThe calculators, estimates, and financial formulas provided on CalculatorVillage.com are for informational and educational purposes only. They are not intended as certified financial planning, tax, legal, or investment advice. Actual rates, terms, and returns will vary. Always consult with a qualified professional before making significant financial decisions.