Chicken Genetics Calculator
Pick a cross and the two parent birds to see what colours the chicks will hatch, and whether you will be able to tell cockerels from pullets on hatch day.
Black25%
Blue50%
Splash25%
Sexable at hatch?No
Blue is never true-breeding: a blue bird carries one copy of the gene, so blue × blue always throws some black and some splash. Only black × splash gives 100% blue.
Blue, black and splash
Blue is the cross everyone tries first, and the one that surprises everyone. The blue gene isincompletely dominant: one copy dilutes black to slate blue, two copies dilute it further to splash, which is a pale white-grey flecked with darker patches. A black bird has no copies at all.
Because a blue bird always carries exactly one copy, blue can never breed true. Mate two blues and the copies shuffle: a quarter of the chicks get no blue gene and hatch black, half get one and hatch blue, a quarter get two and hatch splash. That 25/50/25 split is the reason a pen of blue Andalusians or blue Orpingtons keeps throwing birds that are not blue.
If you want nothing but blue chicks, the cross is black × splash. Every chick then gets exactly one copy of the gene, one from each parent, and every chick hatches blue. Blue × black gives half blue and half black; blue × splash gives half blue and half splash.
The colours in a Punnett square
- Black × black — 100% black
- Black × blue — 50% black, 50% blue
- Black × splash — 100% blue
- Blue × blue — 25% black, 50% blue, 25% splash
- Blue × splash — 50% blue, 50% splash
- Splash × splash — 100% splash
Sex-link crosses: telling cockerels from pullets at hatch
Chickens determine sex the opposite way to mammals. Cockerels carry two Z chromosomes, pullets carry one Z and one W. The consequence that matters for breeding is this: a pullet inherits her single Z from her father, while a cockerel gets one Z from each parent.
That makes any gene living on the Z chromosome a potential sexing tool. Both the silver/gold gene and the barring gene sit there. Put a gold cock over a silver hen and the cockerels inherit their mother's silver and hatch pale, while the pullets inherit their father's gold and hatch reddish-buff. That is the red sex-link, sold commercially as ISA Brown, Golden Comet and Red Star. The same logic with barring — a non-barred cock over a barred hen — gives barred cockerels and solid pullets, which is the black sex-link.
Run either cross backwards and it stops working entirely. A silver or barred cock passes his dominant gene to every single chick, so they all look identical and nothing is sexable. This is the mistake that catches most people out: the dominant bird has to be on the hen side.
Note that sex-linked offspring do not breed on as sex-links. Cross two red sex-links together and the neat sorting disappears — you have to remake the cross from the original parent breeds each time.
What this calculator does not cover
Chicken colour genetics runs to dozens of interacting loci: the E-locus base colours, mottling, lacing, columbian restriction, dominant and recessive white, and more. This tool covers the three crosses that are cleanly predictable and that backyard breeders actually plan around. Anything involving white birds in particular can hide almost any genotype underneath, so treat a white parent as an unknown.
Planning a hatch from these eggs? The hatch date calculator gives you the 21-day schedule, and you will need a cock in the flock at all for fertile eggs — see do chickens need a rooster to lay eggs. Breed egg colours and temperaments are on the breeds chart.
How we calculate it
Blue is an autosomal incompletely dominant gene: 0 copies black, 1 copy blue, 2 copies splash, combined by Punnett square. Silver/gold and barring are Z-linked; cockerels are ZZ and pullets ZW, so a pullet takes her Z from the sire. A recessive sire over a dominant dam therefore gives dominant-phenotype cockerels and recessive-phenotype pullets.
Based on:
- Chickens use ZW sex determination; males are ZZ and females ZW (Poultry Extension)
- Sex-linked crosses and how feather colour identifies chick sex at hatch (Mississippi State Extension)
- Basic poultry breeding and inheritance for small flocks (UGA Extension)
Figures are typical guidelines for planning. Your birds, breed, climate, and feed will vary.
Frequently asked questions
What do you get when you breed two blue chickens?
Blue × blue gives roughly 50% blue, 25% black and 25% splash. Blue never breeds true because a blue bird carries only one copy of the gene. The only cross that gives 100% blue chicks is black × splash.
How does a sex-link cross work?
Chickens use ZW sex determination: cockerels are ZZ and pullets are ZW. A pullet takes her single Z from her father. Put a gold cock over a silver hen and the cockerels hatch silver while the pullets hatch gold, so you can sex them by down colour at hatch.
Why does my sex-link cross not work in reverse?
Because the cock passes a Z to every chick. A silver or barred cock gives all his chicks the dominant gene, so they all look the same and nothing is sexable. The dominant bird has to be the hen.