Online blood calculators are tools that can give you an estimate of your blood type.

Taking a blood test in real life could be scary. Some people have a genuine phobia of needles and other sharp objects.

These online tools can be used by such people, and give them a better idea of what their blood type is.

It is important to note that these online blood type calculator tools cannot give an accurate result, that is only possible with an actual lab test with real blood.

What are blood types?

There are 8 possible blood types that occur in humans. Blood types differ from each other due to alleles.

Alleles are responsible for every human being’s genetic trait. These traits are inherited from our parents and are responsible for our body’s genetic structure.

An example of this is height, there are 2 alleles for height, one for shortness and the other for tallness. Depending on which allele you inherited you could be either short or tall.

It’s the same case with blood types. Blood types that exist in human beings are A+, B+, AB+, O+, A-, B-, AB-, and O-.

The Letters in the blood types are the 4 groups of blood types namely: A, B, AB, and O.

Each parent gives 1 allele to their offspring, so the offspring gets 1 allele from each parent for a grand total of 2.

If a parent is blood type A, and the other parent has blood type AB, then the child’s blood type will be either A, B, or AB.

blood type

What are blood type calculators?

As previously stated, The blood type calculator is a tool that any human can determine the blood types of a newborn baby or any person here. But keep in mind that this blood type calculator does not tell us exactly.

The information that they require to check the blood type is the blood type of the parents.

If they know the exact blood type of the parents, then they can calculate what the child’s blood type could be.

How do they work?

There are two ways in which these tools calculate the blood type;

blood type of parents

1) using the blood type of parents, or

2) using the alleles of the parents in a Punnett square.

For the first method, such tools only ask you for your mother’s blood type and then your father’s blood type.

For example, let’s say your mother’s blood type is B+, and your father’s blood is A- then the results will say that your blood type could be A, B, or AB and could be either positive or negative.

Good websites that provide these tools have a graphic that shows the percentage of what blood type you could be.

In the example given above the chances of being type, A are = 50%, for type B they are 12.5%, and for type AB they are 37.5%.

The Second method is the Punnett square which relies on alleles. You can choose from two options here: “Monohybrid” and “Dihybrid“.


Before we go further, it would be suitable to explain what a genotype is and what a phenotype is.

The genetic configuration of the alleles is called the genotype. The physical traits that are the result of our genotype are called the ‘phenotype’.

There are 2 kinds of alleles for each gene; a person with blood type A could have the genotype of either “AA”, “Aa”, or “aa”.

Similarly, a blood type B person could have the genotype of either “BB”, “Bb”, or “bb”.

The small letter denotes the recessive gene while the capital letters denote the dominant gene.

In a combination of a dominant and recessive gene, the dominant gene will always win and the phenotype will be according to the dominant gene.

Using this information, the Blood type Punnett square calculator uses a “Punnett” square to determine what the blood types of the offspring could be.

punnet sequare

As usual, the requirement is to know the genotype of the parents. A Punnett square is a square diagram used to measure the probability of specific genotypes occurring from a given pool of parent’s genes.

In the blood calculator tool, the Punnett square method can use the Monohybrid method where each parent has only one allele (only all A/a or all B/b). The diagram for that is smaller.

In the Dihybrid method, the parents have both A/a and B/b alleles. The diagram is larger and the results are more varied.


Online blood type calculators are free tools that are available to anyone. They rely on the vast amount of data that biologists have collected when estimating the blood type.

Their results are based on the averages that have been observed in human beings.

Blood tests can be difficult to do for the average person. These online tools reduce that difficulty drastically but at the cost of accuracy, as it is not possible to determine with 100% accuracy the blood types of someone through calculations.

Read More: 5 Ways to Increase Blood Flow and Circulation.

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