Hair color calculator
Select both parents' hair colors and optionally all four grandparents to get a more accurate prediction. Grandparent information helps identify hidden carrier alleles.
Curious about inheritance patterns?
Use the pedigree tool to map multiple generations and identify which inheritance patterns fit your family.
Open the pedigree toolHow the hair color calculator works
This tool estimates the chance that a child will have blonde, brown, red, or black hair based on the hair colors of the parents. When you add grandparent data, the calculator uses that extra information to make better guesses about what alleles each parent might carry.
Why hair color is polygenic
Hair color is not controlled by a single gene the way some traits are. At least twelve genes contribute, and most of them influence how much and what type of melanin your hair follicles produce. Two types of melanin matter: eumelanin, which is dark brown to black, and pheomelanin, which is reddish-yellow. People with dark hair produce a lot of eumelanin. Blonde hair means very little eumelanin. Red hair comes from high pheomelanin and low eumelanin, driven largely by variants in a gene called MC1R.
The MC1R gene and red hair
MC1R sits on chromosome 16 and codes for a receptor that controls the switch between pheomelanin and eumelanin production. When MC1R works normally, the receptor signals melanocytes to produce eumelanin. When someone inherits two broken copies of MC1R (one from each parent), the switch stays off, and pheomelanin builds up instead. That is why red hair is recessive: you need two non-working copies to see the trait. A person with one working and one broken copy usually has brown or blonde hair but carries the red-hair allele silently. This is why red hair can skip generations. Two brown-haired parents who each carry one MC1R variant have a 25% chance of having a red-haired child with each pregnancy.
Why grandparent data improves the prediction
The other genes involved (OCA2, HERC2, TYRP1, SLC45A2, and others) shift melanin production up or down in smaller increments. Blonde versus brown hair often comes down to how many "light" variants a person carries across several of these genes, not just one switch. Because the trait is polygenic, a hair color calculator that only looks at the parents' visible hair color has limited information. Two parents with light brown hair might each carry several dark alleles they do not express, and their child could end up with much darker hair than either parent. This is why two blonde parents can sometimes have a dark-haired child.
Grandparent data helps because it gives the calculator a window into what alleles the parents might be carrying silently. If one grandparent has red hair, the calculator knows that the parent carrying that lineage has at least one MC1R variant, even if that parent's own hair is brown. More family data narrows the range of possibilities.
Limitations
This hair color calculator uses a simplified polygenic model. Real hair color is messier than any model can capture: some genes have incomplete dominance, environment plays a role in melanin production, and the model does not account for hair color changes during childhood (many children born with blonde hair darken over time). Treat the percentages as rough estimates, not guarantees.
Frequently asked questions
What gene causes red hair?
The MC1R gene on chromosome 16 is the main gene responsible for red hair. It codes for a receptor that controls whether melanocytes produce dark eumelanin or reddish pheomelanin. When someone inherits two non-working copies of MC1R, pheomelanin builds up and the result is red hair.
Why does hair color skip generations?
Hair color can skip generations because many hair color alleles are recessive. A parent can carry a hidden allele without expressing it. If both parents carry the same recessive allele (like an MC1R variant for red hair), their child has a chance of expressing a trait that neither parent shows.
Can two blonde parents have a dark-haired child?
Yes. Blonde hair usually means low eumelanin, but a blonde person can still carry several alleles for higher melanin production that are not expressed. If both parents pass enough of those alleles to the child, the child can have darker hair than either parent.
Can two brown-haired parents have a red-haired child?
Yes. Brown hair is dominant over red, so a brown-haired parent can carry one MC1R variant without any sign of red hair. If both parents are carriers, each child has a 25% chance of inheriting two MC1R variants and having red hair.
Is hair color dominant or recessive?
Neither, strictly speaking. Dark hair is generally dominant over light hair, and red hair (driven by MC1R) is recessive. But hair color is polygenic, meaning many genes contribute, and the result is more like a spectrum than a simple dominant-or-recessive call.