This hair color calculator predicts a baby’s hair color from the alleles of both parents and draws the Punnett square behind the answer. Four colors are on a single dominance chain, black over brown over red over blonde, so the 2 × 2 square shows which combinations give which color and how likely each one is. Pick the parents’ alleles from the four pickers and the square, the icons and the odds update immediately.
The gene has four alleles: K for black, N for brown, R for red and L for blonde, in that order of dominance. Two brown alleles (NN) and one brown with one blonde (NL) both give brown hair, because N hides L. Red needs R without K or N above it, so RR and RL are red; blonde needs LL. The pattern explains a familiar family story: two brown-haired parents who each carry a blonde allele can have a blonde child, because the square puts LL in one of its four cells.
The calculator opens with a brown parent carrying blonde (NL) and a brown parent carrying red (NR). The square holds NN, NR, NL and LR. The first three are brown, and LR is red because R outranks L, so the odds read brown 75% and red 25%. The genotype line reports four different genotypes, one homozygous and three heterozygous, and the pattern is the 3:1 classic. Swap the second parent to LL (blonde) and the cross NL × LL gives brown 50% and blonde 50%, a test-cross 1:1 pattern. Put a black allele anywhere and it dominates every cell it touches: KL × LL still gives 50% black.
Real hair color is polygenic. MC1R variants drive most red hair, and dozens of other genes shift how much dark eumelanin and reddish pheomelanin the hair makes; many babies are born blonde and turn brown by school age. The single-gene chain is a way to learn how dominant and recessive alleles combine, so use the percentages to reason about inheritance rather than to plan for a particular child.
Yes, if both carry a hidden red allele. NR × NR puts RR in 1 of the 4 cells, so each child has a 25% chance of red hair while 75% are brown.
In this model red (R) is recessive to black and brown but dominant over blonde, so a child needs RR or RL to have red hair. In real genetics red hair comes mainly from recessive variants of the MC1R gene, which is why it can skip generations.
Choose the two alleles each parent carries and the square gives the percentage chance of black, brown, red and blonde. If a parent has a lighter-haired parent themselves, they probably carry that lighter allele.
Black is dominant over all the others, then brown, then red, with blonde recessive to everything. A child shows the higher of their two alleles on that list.
It is a one-gene teaching model. Real hair color depends on many genes, mainly MC1R and the pigment genes shared with skin and eyes, and it often darkens through childhood, so treat the result as odds for a classroom, not a forecast.