Eye color is influenced by at least 16 genes, yet the OCA2 and HERC2 locus determine the majority of variation. Our 6-SNP model based on the 2009 Rotterdam study (Liu et al., Current Biology) predicts brown versus blue with over 90% accuracy using DNA markers, while parent-plus-grandparent observation achieves ~70-85% accuracy. Recessive genes such as SLC24A4, TYR, SLC45A2, and IRF4 shape green, hazel, gray, and amber shades. Because the model weights four grandparents, it captures hidden recessive carriers that a two-parent quiz typically misses.Learn more about the genetics of eye color.OCA2 gene information HERC2 gene information
How to use the baby eye color calculator in 3 steps
- Select both parent eye colors. Each parent passes on about half the genetic input.
- Enter the four grandparent eye colors. This step spots hidden recessive copies, for example a brown-eyed parent with a blue-eyed father who likely carries both.
- Press Calculate to see a stacked bar of percentages. Fill in all six boxes for the best read. Each box moves the result by 5 to 15%.
Understanding your results
Treat the numbers as probabilities, not certainties. If you see 60% brown, 25% green and 15% blue, brown appeared about four times more often than blue in the model, yet recessive shuffles can still produce blue eyes. The six percentages always add to 100%, representing all possible outcomes.
How to read the chart
- A higher number means that gene combination came up more often in the 6-SNP model
- A lower number means a recessive pairing or rare genetic shuffle, still possible
- Adding four grandparents usually tightens the top color by about 10% toward that grandparent's color
- The total of all six boxes always equals 100%
- MedlinePlus for clinical reference on eye color inheritance
The genetics behind eye color
More melanin in the iris means a darker eye. OCA2 builds that melanin. HERC2 rs12913832 works like a dimmer for OCA2. GG almost always reads as brown, GA leans green or hazel, AA leans blue or gray. A few smaller spots in the DNA adjust amber and hazel.OCA2 gene details HERC2 gene details
- OCA2 controls how much melanin sits in the iris.
- HERC2 quiets OCA2 down in blue eyes.
Why grandparents matter
Each person carries two copies of the main eye color switch. When both copies match, the parent can only pass that type. When they differ, for example brown with blue, the eyes look brown yet blue still gets passed on about half the time. You cannot tell by looking, which is why tools that ask for parents only lose accuracy.
Punnett square: Brown (Bb) with Blue (bb)
This pairing gives 50% brown and 50% blue. A brown grandparent pulls it toward 75% brown. Gray, hazel and green need a second gene spot.
Can two blue-eyed parents have a brown-eyed child?
By the old single gene rule, no. In real families, yes, but it stays rare at 1 to 6%. Eye color uses many genes, so variants in SLC24A4, SLC45A2, TYR, IRF4 can push a blue with blue pairing toward brown or hazel. When that happens the child almost always has a brown-eyed grandparent. This calculator leaves room for it. A pure blue with blue pairing still shows 2 to 5% brown when grandparents include brown.GHR eye color overview
Baby eye color chart by parents – 6-SNP genetic model
Looking for a baby eye color chart or newborn eye color chart? Start here. This detailed chart accounts for 6-SNP genetic modeling versus simple Mendelian inheritance. Table A fits real families where most brown-eyed parents carry one brown and one blue copy. Table B shows the textbook version where each type counts the same. Grandparents move either table by about 10% in their direction. Use the calculator above for your personalized 6-color probability split.
Table A: common family pattern
| Parent Pair | Brown | Blue | Green | Hazel / Gray / Amber |
|---|---|---|---|---|
| Brown × Brown | 75% | 6.25% | 9% | 9.75% |
| Brown × Blue | 50% | 25% | 13% | 12% |
| Brown × Green | 56% | 12% | 20% | 12% |
| Blue × Blue | 2% | 85% | 7% | 6% |
| Blue × Green | 12% | 45% | 30% | 13% |
| Green × Green | 25% | 15% | 40% | 20% |
Table B: textbook pattern
| Parent Pair | Brown | Blue | Green | Other |
|---|---|---|---|---|
| Brown × Brown | 56% | 18.7% | 12.5% | 12.8% |
| Green × Green | 15.6% | 9.3% | 56% | 19% |
Sources: Liu et al. 2009, Sturm 2009, White and Rabago-Smith model. Use the calculator above for your six color split.
Eye Color Genetics Quick Reference
- OCA2: Primary melanin production gene on chromosome 15
- HERC2: Regulatory gene that controls OCA2 expression (rs12913832)
- SLC24A4: Modifier gene affecting melanin distribution
- TYR: Tyrosinase enzyme gene - albinism pathway
- SLC45A2: Melanogenesis-associated protein gene
- IRF4: Transcription factor influencing pigmentation
Melanin and rarity at a glance
| Eye Color | Melanin | Genetic Strength | Global Rarity |
|---|---|---|---|
| Brown | High | Strong dominant | ~79% |
| Blue | Very low | Recessive | ~8% |
| Hazel | Medium | Mixed (brown + green) | ~5% |
| Amber | Medium-high | Recessive + lipochrome | ~5% |
| Green | Low-medium | Moderate recessive | ~2% |
| Gray | Very low + collagen | Recessive variant of blue | ~1% |
Heterochromia
Complete means one brown and one blue eye. Sectoral means a brown patch inside a blue iris. It shows up in about 0.6% of people through mosaicism or Waardenburg syndrome. A basic 6-SNP model does not predict it. Check with an eye doctor if color changes suddenly.
When do babies eyes change color
| Age | What happens | What you will see |
|---|---|---|
| Birth | Low melanin, light scatters | Often blue or gray, even if brown comes later |
| 1 to 3 months | Melanocytes wake up | Darkening starts if brown or green genes are present |
| 6 to 9 months | About 80% of final melanin | Close to true color |
| 9 to 12 months | Color steadies | Set for most babies, with small shifts possible to age 3 |
Source: American Academy of Ophthalmology and WhatToExpect.
Ethnicity and world eye color
Brown is most common in African, East Asian and South Asian families, over 80%. Blue and gray peak in Northern and Eastern Europe at 30 to 50%, with Estonia near 99% light eyes. This calculator starts from a world baseline of 79% brown, but your family history matters more than ancestry. Mixed ancestry moves the chart in proportion.World prevalence data
Sources and review
Written by Zencalcy Editorial (Genetics). Medically reviewed. Last updated 28 Aug 2026. Related: all calculators • BMI predictor • calorie genetics
- Liu et al. (2009) "Prediction of eye color using 6 SNPs" in Current Biology (Rotterdam Study, 90.5% brown and blue) DOI
- Sturm et al. (2008) on the OCA2 and HERC2 region overview
- White and Rabago-Smith eye color inheritance model with polygenic tables.
- MedlinePlus Genetics on eye color (16 plus genes) and AAO baby eye color timeline