This eye color calculator draws the 2 × 2 Punnett square for a baby’s eye color from the two alleles each parent carries. Choose the parents’ alleles, and the square fills with iris icons, the genotype in each cell and its share of the offspring, while the list below adds the odds of each color. It is the classic way to answer “what color eyes will my baby have” in a genetics class, and it works as a newborn eye color predictor as long as you remember it is a one-gene model.
The tool uses one gene with six alleles, ranked from most to least dominant: brown (B), hazel (H), green (G), amber (A), gray (g) and blue (b). Every person carries two alleles, and the eye shows whichever of the two sits higher on the chain. A B allele hides anything below it, so Bb, BH and BG all look brown; a person only shows blue when both alleles are b. That is why blue eyes can reappear after skipping a generation: two brown-eyed parents can each pass on a hidden b.
Two brown-eyed parents who both carry a blue allele are Bb × Bb. The square holds BB, Bb, Bb and bb: three brown cells and one blue, so the calculator reports brown 75% and blue 25%, a 1:2:1 genotype ratio and the 3:1 Mendelian pattern. Change the father to bb (blue eyes) and the cross becomes Bb × bb: two cells Bb and two cells bb, a 50% chance of each color. Mix the chain and the middle colors appear: a green-eyed parent carrying blue (Gb) with a hazel parent carrying blue (Hb) gives hazel 50%, green 25% and blue 25%, because H outranks G in the GH cell.
Real eye color is polygenic. The OCA2 and HERC2 genes control most of the brown-versus-blue difference, and more than a dozen other genes shift the shade, so two blue-eyed parents occasionally have a child with light brown or green eyes, something a single-gene square cannot produce. Newborns’ eyes also keep changing for their first year as melanin builds up. Use the calculator to learn how dominance and Punnett squares work, and the blood type calculator for a trait that really does follow a small number of alleles.
Yes. If both parents are Bb, each carries a hidden blue allele, and the Punnett square gives their child a 1 in 4 chance of bb and blue eyes. The calculator shows this as 25% blue and 75% brown.
No calculator can promise a color, but this one gives the odds. Pick the two alleles each parent carries and the square lists the percentage chance of brown, hazel, green, amber, gray and blue for a baby of that couple.
In this model brown is dominant over everything, blue is recessive to everything, and the full order is brown, hazel, green, amber, gray, blue. A child shows whichever of their two alleles sits higher on that list.
You cannot see a recessive allele directly. Look at your parents and siblings: a brown-eyed person with a blue-eyed parent must carry a blue allele (Bb). The 3-generation trick is simply to reason back from grandparents to work out the hidden allele.
It is a teaching model. Real eye color depends on several genes, mainly OCA2 and HERC2, plus how much pigment the iris makes, so real families show more variety than one gene predicts. Treat the percentages as classroom odds, not a medical forecast.