Baby Eye Color Calculator

How baby eye colour is inherited

Eye colour is polygenic, which means several genes team up to decide the final shade — there is no single “eye colour gene.” The two biggest players sit close together on chromosome 15: a gene called OCA2, which controls how much brown pigment (melanin) the iris makes, and a neighbouring gene called HERC2, which acts like a switch that turns OCA2 up or down.

As a rough rule, brown tends to dominate and blue is recessive: more melanin in the iris reads as brown, while very little melanin scatters light and looks blue. Each parent passes on one copy of these variants, so a child inherits a mix from both sides.

Because more than two genes are involved, the in-between shades — green and hazel — and the occasional surprise are completely normal. Two parents can carry hidden variants that only show up in their child, which is exactly why eye colour can seem to “skip” a generation.

How the calculator works

The Baby Eye Color Calculator uses a simplified inheritance model based on the two parents’ eye colours. It takes each parent’s colour, works through the likely combinations they could pass on, and tallies how often the child ends up brown, green, or blue.

The result is shown as a set of chances — for example, a higher brown percentage when one or both parents have brown eyes, and a bigger blue or green slice when both parents have lighter eyes. It is a quick estimate of the most likely outcomes, not a measurement of your baby’s actual genes.

Can two blue-eyed parents have a brown-eyed child?

It is rare, but genuinely possible. The simplified textbook model behind this calculator puts the chance of a brown-eyed baby for two blue-eyed parents close to zero (it shows it as rare), because blue generally behaves as recessive and brown as dominant.

But real genetics has exceptions. Eye colour is polygenic, so a parent who looks blue-eyed can still carry small amounts of brown-leaning variants that combine in an unexpected way. It doesn’t happen often, but a brown-eyed child of two blue-eyed parents is a real outcome — not a reason to doubt anyone. The honest takeaway: the calculator reflects the typical pattern, while nature keeps a few surprises in reserve.

When does a baby’s eye colour settle?

Many babies are born with eyes that look blue, grey, or slate, then change, usually between 3 and 9 months, as melanin builds up in the iris. Some keep shifting until around age three before they fully settle.

The change usually runs from lighter to darker — a blue-eyed newborn may turn green, hazel, or brown as melanin builds up. A sudden change in a child’s eye colour is different: get it checked by an eye doctor. So if you are checking the calculator against a newborn’s eyes, remember the colour you see in the first few weeks may not be the colour they keep.

Just for fun — not a medical or paternity test

This calculator is an entertainment estimate built on a simplified model. It is not a medical tool, a genetic test, or a paternity test, and it cannot diagnose or rule out anything. Because eye colour depends on many genes plus a bit of luck, no calculator can promise the colour your baby will have.

Enjoy it as a playful guess while you wait to meet your little one — and if you have real questions about genetics or your pregnancy, your healthcare provider or a genetic counsellor is the right person to ask.