What eye color will the baby have if one parent has brown eyes and the other blue?
If one parent has brown eyes and the other blue, the simple two-gene model behind our calculator gives the baby the rough chances below. It is a teaching model, not a prediction: real eye color depends on many genes.
Rough chance for the baby
A simple teaching model, not a prediction. Real eye color depends on many genes.
Why these chances
The blue-eyed parent can only pass on light-eye versions of the genes, so it comes down to the brown-eyed parent. If they carry a hidden lighter copy and pass it on, the baby can have blue or green eyes. If they pass on brown, the baby's eyes are brown. That's why this pairing gives brown about two times in three, with blue and green sharing the rest.
What the grandparents change
If the brown-eyed parent has a blue-eyed mother or father, they must carry a hidden blue copy, and the model's chance of a blue-eyed baby rises from about 17% to 38%.
Add grandparents in the calculator
What the model leaves out
The model uses only two genes and treats every version of a gene as equally common. In reality eye color depends on many genes, how common each version is differs from country to country, and hazel, grey and mixed colors don't fit neatly into three groups. Use the numbers to see how a hidden color can pass down, not to predict your baby.
Other parent combinations
- Brown × Brown
- Brown × Green or hazel
- Brown × Blue or grey
- Green or hazel × Green or hazel
- Green or hazel × Blue or grey
- Blue or grey × Blue or grey
Frequently asked questions
What eye color will the baby have if one parent has brown eyes and the other blue?
In the simple model, roughly 67% brown, 17% green or hazel and 17% blue. Real families vary, because eye color depends on many genes.
Can a brown-eyed and a blue-eyed parent have a blue-eyed baby?
Yes. If the brown-eyed parent carries a hidden lighter copy, the chance is real. The simple model gives about 17%, and about 38% if the brown-eyed parent has a blue-eyed mother or father.
When will we know the baby's eye color?
Usually within the first year or two. Many babies are born with lighter eyes that darken as melanin builds up in the iris, and most children have their lasting eye color by about age six.